CN120303829A

CN120303829A - Base station antenna having a frequency selective surface having a unit cell including an inductor feature

Info

Publication number: CN120303829A
Application number: CN202380082683.7A
Authority: CN
Inventors: 李海峰; P·J·必思鲁勒斯
Original assignee: Outdoor Wireless Networks LLC
Current assignee: Outdoor Wireless Networks LLC
Priority date: 2022-12-01
Filing date: 2023-09-22
Publication date: 2025-07-11
Also published as: EP4627673A1; WO2024118242A1

Abstract

The base station antenna includes at least two frequency selective surfaces/layers, wherein an array of low-band radiating elements protrudes from the front of a front layer in the FSS layer. The FSS layer is provided with unit cells having inductor characteristics and may be arranged as two stacked layers, each stacked layer including unit cells having aligned inductor characteristics with different inductor values, thereby providing improved reflectivity and ultra-wideband performance. The antenna array is located behind the rear layer in the at least two FSS layers and is configured to transmit signals through the at least two FSS layers and out of the front radome of the base station antenna.

Description

Base station antenna with frequency selective surface having unit cell including inductor feature

RELATED APPLICATIONS

The present patent application claims the benefit and priority of U.S. provisional application Ser. No. 63/385,670 filed on 1 month 12 of 2022, the contents of which are hereby incorporated by reference as if fully set forth herein.

Background

The present invention relates generally to radio communications, and more particularly to a base station antenna for a cellular communication system.

Cellular communication systems are well known in the art. In a cellular communication system, a geographical area is divided into a series of areas called "cells" that are served by corresponding base stations. A base station may include one or more antennas configured to provide two-way radio frequency ("RF") communication with mobile users within a cell served by the base station. In many cases, each cell is divided into "sectors". In one common configuration, a hexagonally shaped cell is divided into three 120 ° sectors in the azimuth plane, and each sector is served by one or more base station antennas having an azimuth half-power beamwidth (HPBW) of approximately 65 °. Typically, the base station antennas are mounted on towers or other elevated structures, wherein a radiation pattern (also referred to herein as an "antenna beam") is generated by the outwardly directed base station antennas. Base station antennas are typically implemented as linear or planar phased arrays of radiating elements.

To accommodate the increasing cellular traffic, cellular operators have increased cellular services in various new frequency bands. In order to increase the capacity without further increasing the number of base station antennas, multiband base station antennas have been introduced, which comprise a plurality of linear arrays of radiating elements. In addition, base station antennas are now being deployed that include a "beamformed" array of radiating elements that includes multiple columns of radiating elements. The radios for these beamforming arrays may be integrated into the antennas such that the antennas may perform active beamforming (i.e., the shape of the antenna beams generated by the antennas may be adaptively changed to improve the performance of the antennas). These beamforming arrays typically operate in various portions of the higher frequency band, e.g., the 3.3-5.8GHz band. Antennas with integrated radios that can adjust the amplitude and/or phase of sub-components of an RF signal transmitted through individual radiating elements or small groupings thereof are referred to as "active antennas. An active antenna may generate a narrow beamwidth, high gain antenna beam by varying the amplitude and/or phase of sub-components of an RF signal transmitted through the antenna, and may steer the generated antenna beam in different directions.

With the development of wireless communication technology, integrated base station antennas have emerged that include a passive module and an active antenna module with an active antenna. The passive module may include one or more passive arrays of radiating elements configured to generate a relatively static antenna beam, such as an antenna beam configured to cover a 120 degree sector (in the azimuth plane) of the base station antenna. Passive arrays may include arrays that operate according to second generation (2G), third generation (3G) or fourth generation (4G) cellular standards. These passive arrays are not configured to perform active beam forming operations, but they typically have Remote Electronic Tilting (RET) capability, which allows the shape of the antenna beam to be changed by electromechanical means in order to change the coverage area of the antenna beam. The active antenna module may include one or more arrays of radiating elements operating in accordance with a fifth generation (or later) cellular standard. These arrays typically have individual amplitude and phase control over a subset of the radiating elements therein and perform active beam shaping.

Fig. 1 shows an example of a prior art base station antenna 10 comprising a pair of beamforming arrays and associated beamforming radios. When the antenna 10 is installed for normal operation, the base station antenna 10 is typically installed with the longitudinal axis L of the antenna 10 extending along a vertical axis (e.g., the longitudinal axis L may be substantially perpendicular to a plane defined by the horizon). The front surface of the antenna 10 is mounted opposite a tower or other mounting structure, pointing toward the coverage area of the antenna 10. The antenna 10 includes a radome 11 and a tip cover 20. The antenna 10 also includes a bottom end cap 30 that includes a plurality of connectors 40 mounted therein. As shown, the radome 11, the top cover 20 and the bottom cover 30 define an outer housing 10h of the antenna 10. The antenna assembly is housed within the housing 10h.

The antenna 10 may include one or more radios mounted to the rear of the housing 10 h. The heat generated in the radio(s) is transferred to the heat sink and spread to its fins (not shown). Additional details of exemplary conventional base station antennas can be found in co-pending WO2019/236203 and WO2020/072880, the contents of which are incorporated herein by reference as if fully set forth herein.

Disclosure of Invention

Embodiments of the present invention relate to a base station antenna having one or more Frequency Selective Surface (FSS) layers configured with unit cells having inductor features to allow high band radiating elements to propagate electromagnetic waves through an aperture and reflect lower band signals from lower band radiating elements in front of the one or more FSS layers.

Aspects of the present invention relate to a base station antenna including a first Frequency Selective Surface (FSS) having a first array of unit cells and a second FSS having a second array of unit cells. The first FSS is stacked in front of the second FSS in the base station antenna in the Z-direction. Each unit cell in the first array of unit cells and each unit cell in the second array of unit cells includes a plurality of spaced apart inductor structures, and the first unit cell in the first array of unit cells is aligned with the first unit cell in the second array of unit cells in the X-Y direction, whereby the respective inductor structure of the first unit cell is aligned with the respective inductor structure of the first unit cell in the second array of unit cells.

A first unit cell in the first array of unit cells may have a perimeter, wherein a first adjacent unit cell and a second adjacent unit cell share a perimeter side, and an inductor structure of the first adjacent unit cell and the second adjacent unit cell may be electrically connected.

The inductor structures of the first unit cells in the first array and the first unit cells in the second array may be arranged as curved protrusions on or adjacent to the outer periphery of the respective first unit cells.

The first unit cells in the first array of unit cells and the second array of unit cells may each have a center and four linear segments protruding outward from the center. The four linear segments may be orthogonal to each other, and the four linear segments may each be incorporated into at least one of their respective inductor structures.

The respective inductor structure of each unit cell may have protrusions protruding outwardly in series from opposite sides of the lateral or longitudinal centerline of the corresponding linear segment. The protrusion of the inductor structure of the first unit cell in the second array may extend beyond the boundary of the protrusion of the first unit cell in the first array of unit cells.

The inductor structures of adjacent unit cells in the first array of unit cells may define a parallel inductor circuit.

One inductor structure of a first unit cell in the first array of unit cells may be incorporated into one inductor structure of an adjacent second unit cell in the first array of unit cells at a common peripheral side.

The inductor structure may be located only on the periphery of the respective unit cells in the first array of unit cells and the second array of unit cells.

The first unit cell in the first array of unit cells and the second array of unit cells may further comprise a curved section around the center. The four linear segments may extend from four sides of a curved segment around the center.

The four linear segments may be inner linear segments, and the first unit cell may further include four outer linear segments. One of the inductor structures may be located between a pair of outer and inner linear segments.

The base station antenna may also include a third FSS located after the second FSS, the third FSS having a third array of unit cells.

The base station antenna may also include a passive antenna having the first FSS and the second FSS in a housing, and an active antenna unit located behind the housing.

The base station antenna may also include a first plurality of radiating elements located forward of the first FSS and a second plurality of radiating elements located rearward of the second FSS.

The first plurality of radiating elements may operate in a first frequency band and the second plurality of radiating elements may operate in a second frequency band.

The first plurality of radiating elements may have low band radiating elements configured to operate in a first frequency band, and the second plurality of radiating elements may have higher band radiating elements configured to operate in a second frequency band, the second frequency band encompassing higher frequencies than the first frequency band.

The first FSS and the second FSS may be configured to allow RF energy in the second frequency band to propagate through the first FSS and the second FSS.

The first FSS may have a first subset of the first array of unit cells configured to block and/or reflect RF energy in a first frequency band while allowing RF energy in a second frequency band to propagate through the first FSS. The first FSS may also have a second subset of the first array of unit cells configured to block and/or reflect RF energy in the first frequency band and RF energy in a third frequency band. The third frequency band has frequencies between the first frequency band and the second frequency band.

The first subset of the first array of unit cells may be located at an upper portion of the base station antenna. The second subset of the first array of unit cells may have unit cells to the right of the first subset of unit cells and may also have unit cells to the left of the first subset of unit cells.

The first plurality of radiating elements may have high-band radiating elements operating in at least a portion of a 3.2-4.1GHz band, and the second plurality of radiating elements may have radiating elements operating in at least a portion of a lower band than the high-band radiating elements.

The first FSS and the second FSS may be configured to allow RF energy in at least a portion of the 3.2-4.1GHz band to propagate through the first FSS and the second FSS.

The second plurality of radiating elements may be arranged as a multi-column array in an active antenna module.

At least some of the unit cells in the first array of unit cells and/or the second array of unit cells may include at least one transmission line (TX) segment configured to be electrically coupled to at least one inductor structure.

The length of the at least one TX line segment may be configured such that a radio frequency signal from the radiating element passing through the at least one TX line segment is subjected to a 180 degree phase shift at a defined frequency.

The length of the at least one TX line segment may be about half a wavelength defining a frequency response point. Alternatively, the limiting frequency may be the second frequency response point f2 such that the unit cell defines a dual response frequency band.

Some aspects of the invention relate to a base station antenna that includes a first Frequency Selective Surface (FSS) that includes a first array of unit cells and a second FSS that includes a second array of unit cells. The first FSS is stacked in front of the second FSS in the base station antenna in the Z-direction. At least some of the unit cells in the first array of unit cells and the second array of unit cells are configured to provide an equivalent circuit comprising at least one inductor and at least one transmission line (TX) segment configured to be electrically coupled to the at least one inductor.

The length of the at least one TX line segment may be about half a wavelength defining a frequency response point.

The unit cells provided by the first array and the unit cells provided by the second array may be electrically coupled.

A first unit cell in the first array of unit cells may be electrically coupled to a first unit cell in the second array of unit cells, whereby the first unit cells cooperate to define an equivalent circuit to reject or block radio frequency signals from radiating elements operating in a first frequency band and to pass signals from radiating elements operating in a second frequency band.

Still other embodiments relate to a grid reflector for a base station antenna, the grid reflector comprising a Frequency Selective Surface (FSS) comprising an array of unit cells. At least some of the unit cells in the array of unit cells have at least one transmission line (TX) segment.

The length of the at least one TX line segment is about half a wavelength of the defined frequency.

The at least one TX line segment may be configured such that a radio frequency signal from the radiating element passing through the at least one TX line segment is subjected to a 180 phase shift at a defined frequency.

At least some of the unit cells having the at least one transmission line segment reject radio frequency signals in a first frequency band and a second, larger frequency band corresponding to the defined frequency.

The at least one TX line segment may comprise adjacent parallel conductive lines.

Still other embodiments relate to a grid reflector for a base station antenna, the grid reflector comprising a Frequency Selective Surface (FSS) comprising a first array of unit cells having a first configuration and a second array of cells having a second configuration. The first array includes unit cells having a square shape, and the second array includes unit cells having a hexagonal shape. The first array extends inwardly across 30-80% of the width of the FSS and the second array is disposed in two columns on the right and left portions of the first array.

At least some of the unit cells in the array of unit cells may include at least one transmission line (TX) segment having a length configured such that a radio frequency signal from the radiating element passing through the at least one TX line segment undergoes a 180 degree phase shift at a defined frequency.

The FSS may be configured to have a response frequency f0 of about 2.5GHz, and may provide a band pass frequency range and a band reject frequency range.

The at least one TX line segment may have a length L that is about half a wavelength defining a frequency response point.

The base station antenna may include a passive module and/or passive antenna components and an active antenna module, which may be mounted at a location corresponding to the frequency selective surface.

According to embodiments of the present disclosure, the frequency selective surface is provided as a first frequency selective surface and a second frequency selective surface, one stacked in front of the other, and may be configured to allow electromagnetic waves emitted by the active module to pass through.

It should be noted that various aspects of the present disclosure described with respect to one embodiment may be included in other different embodiments even if not specifically described with respect to the other different embodiments. In other words, all embodiments and/or features of any embodiment may be combined in any way and/or combination, as long as they are not contradictory to each other.

Drawings

Fig. 1 is a perspective view of a prior art base station antenna.

Fig. 2A is a rear perspective view of an exemplary base station antenna coupled to an active antenna module according to an embodiment of the present invention.

Fig. 2B is a side rear perspective view of another exemplary base station antenna coupled to an active antenna module in accordance with an embodiment of the present invention.

Fig. 3 is a perspective view of an exemplary primary reflector that may be provided in a base station antenna, such as the base station antenna shown in fig. 2A or 2B, in accordance with an embodiment of the present invention.

Fig. 4A is a perspective view of a mesh reflector of a base station antenna according to an embodiment of the present invention.

Fig. 4B is a front view of the grid reflector shown in fig. 4A.

Fig. 5 is a greatly enlarged unit cell of a grid reflector of a base station antenna according to an embodiment of the present invention.

Fig. 6 is a schematic top view of first and second FSS layers stacked in the fore-and-aft (Z) direction, each having a unit cell with the inductor features of the corresponding FSS, according to an embodiment of the present invention.

Fig. 7 is a schematic top view of a first FSS layer, a second FSS layer, and a third FSS layer stacked in a fore-and-aft (Z) direction, each having a unit cell with an inductor feature of a corresponding FSS, according to an embodiment of the present invention.

Fig. 8 is a greatly enlarged front view of the first FSS layer and the second FSS layer shown in fig. 6 with aligned unit cells (aligned in X, Y directions) according to an embodiment of the present invention.

Fig. 9 is a greatly enlarged front view of adjacent unit cells of the first FSS layer and the second FSS layer shown in fig. 8 according to an embodiment of the present invention.

Fig. 10A is a greatly enlarged front view of another embodiment of a unit cell with an inductor feature according to an embodiment of the present invention.

Fig. 10B is a greatly enlarged front view of another embodiment of a unit cell with an inductor feature similar to that of fig. 10A, in accordance with an embodiment of the present invention.

Fig. 10C is an exemplary wideband FSS equivalent circuit provided by the unit cell of fig. 10B and/or 10C in accordance with an embodiment of the present invention.

Fig. 11 is a greatly enlarged front view of yet another embodiment of a unit cell with an inductor feature according to an embodiment of the present invention.

Fig. 12 is a greatly enlarged front view of an additional embodiment of a unit cell with an inductor feature according to an embodiment of the present invention.

Fig. 13 is a greatly enlarged view of adjacent unit cells of the configuration shown in fig. 12 according to an embodiment of the present invention.

Fig. 14 is a schematic diagram of two adjacent unit cells showing the centers a, b of the respective adjacent unit cells and an exemplary current flow, according to an embodiment of the present invention.

Fig. 15 is a schematic diagram of a unit cell of an FSS layer showing exemplary radiation directions according to an embodiment of the present invention.

Fig. 16A is an exemplary equivalent circuit provided by the unit cell feature of an embodiment of the present invention.

Fig. 16B is an exemplary equivalent circuit provided by the unit cell feature of an embodiment of the present invention.

Fig. 16C is a graph of simulated response (dB) versus frequency (GHz) for an exemplary wideband FSS having horizontal and vertical equivalent circuits provided by unit cells having the horizontal and vertical equivalent circuits of fig. 16A and 16B, in accordance with an embodiment of the present invention.

Fig. 16D is a graph of simulated response versus frequency (GHz) for an exemplary wideband FSS with an equivalent circuit provided by a unit cell with the equivalent circuit of fig. 16B, in accordance with an embodiment of the present invention.

Fig. 17A is another exemplary equivalent circuit provided by a unit cell feature having transmission line segments in parallel with the parallel LC shown in fig. 16B, in accordance with an embodiment of the present invention.

Fig. 17B is a graph of simulated response (dB) versus frequency (GHz) (with f0 and f 2) versus reference response for the equivalent circuit shown in fig. 17A.

Fig. 18A is another exemplary equivalent circuit provided by a unit cell feature having two TX line segments in parallel with the parallel LC shown in fig. 16B, provided 180 degrees at f2, in accordance with an embodiment of the present invention.

Fig. 18B is a graph of simulated response (dB) versus frequency (GHz) (with f0 and f 2) for the equivalent circuit shown in fig. 18A.

Fig. 19A is another exemplary equivalent circuit provided by a unit cell feature in accordance with an embodiment of the present invention.

Fig. 19B is a front view of an enlarged portion of the FSS showing an exemplary configuration of a unit cell having the equivalent circuit shown in fig. 19A according to an embodiment of the present invention.

Fig. 19C is a graph of simulated response (dB) versus frequency (GHz) (with f0 and f 2) for the exemplary equivalent circuit shown in fig. 19A.

Fig. 20A is another exemplary equivalent circuit provided by a unit cell feature in accordance with an embodiment of the present invention.

Fig. 20B is a front view of an enlarged portion of the FSS showing an exemplary configuration of a unit cell having the equivalent circuit shown in fig. 20A according to an embodiment of the present invention.

Fig. 20C is a graph of simulated response (dB) versus frequency (GHz) (with f0 and f 2), with the equivalent circuit shown in fig. 20A.

Fig. 21A is another exemplary equivalent circuit provided by a unit cell feature in accordance with an embodiment of the present invention.

Fig. 21B is a front view of an enlarged portion of the FSS showing an exemplary configuration of a unit cell having the equivalent circuit shown in fig. 21A according to an embodiment of the present invention.

Fig. 21C is a greatly enlarged front view of a portion of the circuit feature in fig. 21B, showing parallel lines.

Fig. 21D is a graph of simulated response (dB) versus frequency (GHz) (with f0 and f 2) for the exemplary equivalent circuit shown in fig. 21A.

Fig. 22A is another exemplary equivalent circuit provided by a unit cell feature in accordance with an embodiment of the present invention.

Fig. 22B is a front view of an enlarged portion of the dual layer FSS according to an embodiment of the present invention, which shows an exemplary configuration of a unit cell having the equivalent circuit shown in fig. 22A.

Fig. 22C is a graph of simulated response (dB) versus frequency (GHz) (with single resonance f 0) for the exemplary equivalent circuit shown in fig. 22A.

Fig. 23A is another exemplary equivalent circuit provided by a unit cell feature in accordance with an embodiment of the present invention.

Fig. 23B is a front view of an enlarged portion of the double-layer FSS according to an embodiment of the present invention, which shows an exemplary configuration of the unit cell having the equivalent circuit shown in fig. 23A.

Fig. 23C is a graph of simulated response (dB) versus frequency (GHz) (with dual resonances f0, f 2) for the exemplary equivalent circuit shown in fig. 22A.

Fig. 24A is an end view of a portion of an exemplary multi-layer wideband frequency selective surface configuration (facing upward in the z-direction) in accordance with an embodiment of the invention.

Fig. 24B is a front view (x-y direction) of a portion of one layer of the multi-layer wideband frequency selective surface configuration shown in fig. 24A.

Fig. 25A is an exemplary equivalent circuit configuration of a dual layer wideband frequency selective surface according to an embodiment of the invention.

Fig. 25B is a front view of a metamaterial providing unit cells corresponding to the equivalent circuit shown in fig. 25A and optionally using a cut-out region of the main material that can functionally act as a large capacitor and the equivalent circuit can provide a series LC, according to an embodiment of the present invention.

Fig. 25C shows a front view (x-y directions) of a dielectric material providing the equivalent circuit shown in fig. 25A, according to an embodiment of the invention.

Fig. 26 and 27 are front views of additional embodiments of frequency selective surfaces according to embodiments of the present invention.

Fig. 28 is a front view of yet another embodiment of a frequency selective surface according to an embodiment of the invention showing differently shaped unit cells in different areas of the reflector.

Fig. 29A is an enlarged view of a single solid hexagonal patch that may be used with the hexagonal unit cells shown in fig. 28, according to an embodiment of the invention.

Fig. 29B is an enlarged view of a single hexagonal shaped unit cell, which is a hexagonal perimeter or ring surrounding an open area or area of a different material than the ring that may be used for the hexagonal unit cell shown in fig. 28, according to an embodiment of the invention.

Fig. 30A is a front side perspective view of an antenna assembly and an exemplary grid reflector of a base station antenna in accordance with an embodiment of the present invention.

Fig. 30B is an enlarged front side perspective view of the antenna assembly and top portion of the grid reflector shown in fig. 30A.

Fig. 31A and 31B are simplified side cross-sectional views of an exemplary base station antenna and cooperating active antenna module in accordance with an embodiment of the present invention.

Fig. 32A-32G are front side partial transparent views of portions of a base station antenna showing examples of stacked reflector configurations, according to embodiments of the present invention.

Detailed Description

Fig. 2A illustrates a base station antenna 100 according to some embodiments of the invention. In the following description, the base station antenna 100 will be described using the following terms assuming that the base station antenna 100 is mounted for use on a tower, mast, or other mounting structure, with the longitudinal axis L of the base station antenna 100 extending along a vertical axis, the front of the base station antenna 100 being mounted opposite the tower, mast, or other mounting structure that is directed toward the target coverage area of the base station antenna 100, and the rear 100r of the base station antenna 100 facing the tower or other mounting structure. It should be appreciated that the base station antenna 100 may not always be mounted such that its longitudinal axis L extends along a vertical axis. For example, the base station antenna 100 may be tilted slightly (e.g., less than 10 °) relative to the vertical axis such that the resulting antenna beams formed by the base station antenna 100 each have a small mechanical downtilt.

The base station antenna 100 may be coupled to or include at least one active antenna module 110. The term "active antenna module" is used interchangeably with "active antenna unit" and "AAU" and "active antenna" and refers to a cellular communication unit comprising radio circuitry and associated radiating elements. The radio circuitry can electronically adjust the amplitude and/or phase of the subcomponents of the RF signal output to the different radiating elements of the array or group thereof. The active antenna module 110 includes radio circuitry and radiating elements (e.g., a multiple-input multiple-output (mMIMO) beamforming antenna array) and may include other components such as filters, calibration networks, antenna Interface Signal Group (AISG) controllers, and the like. The active antenna module 110 may be provided as a single integrated unit or as a plurality of stackable units including, for example, a first subunit and a second subunit (e.g., a wireless subunit (box) with radio circuitry and an antenna subunit (box) with a multi-column array of radiating elements), and the first and second subunits are stackable attached together in the front-to-back direction of the base station antenna 100, with the radiating element 1195 of the antenna assembly 1190 (fig. 31A, 31B) closer to the front radome 111f of the housing 100h of the base station antenna 100/the radome 111 of the base station antenna than the radio circuitry unit 1120. In some embodiments, the radiating element 1195 may include a sub-unit separate from the radio circuitry, and the radiating element sub-unit may be mounted within the base station antenna 100 rather than external to the base station antenna 100.

As will be discussed further below, the base station antenna 100 includes an antenna component 190, which may be referred to as a "passive antenna component. The term "passive antenna assembly" refers to an antenna assembly having arrays of radiating elements that are coupled to a radio external to the antenna, typically a remote radio head mounted in close proximity to the base station antenna 100. Each array of radiating elements included in the passive antenna assembly 190 (fig. 20A) is configured to form a static antenna beam (e.g., antenna beams each configured to cover a sector of a base station). The passive antenna assembly 190 may include a reflector 170, 214 having radiating elements protruding in front of the reflector, and the radiating elements may include one or more linear arrays of low band radiating elements operating in all or part of the 617-960MHz band and/or one or more linear arrays of mid band radiating elements operating in all or part of the 1427-2690MHz band. The passive antenna assembly 190 is mounted in the housing 100h of the base station antenna 100, and one or more active antenna modules 110 may be releasably (detachably) coupled (e.g., directly or indirectly attached) to the base station antenna 100.

The base station antenna 100 has a housing 100h. The housing 100h may be substantially rectangular, having a flat rectangular cross section. The housing 100h may be provided to define at least a portion of the radome 111, wherein at least the front side 111f is configured as a dielectric cover that allows RF energy to pass in a particular frequency band. The housing 100h may also be configured such that the rear portion 100r defines a rear side 111r radome opposite the front side radome 111 f. Optionally, the housing 100h and/or radome 111 may further comprise two (narrow) side walls 100s, 111s facing each other and extending rearwardly between the front side 111f and the rear side 111 r. In general, the top side 100t of the housing 100h may be sealed in a watertight manner and may include an end cap 120, and the bottom 100b of the housing 100h may be sealed with a separate end cap 130. At least a portion of the front side 111f, the side walls 111s, and generally the back side 111r of the radome 111 is substantially transparent to Radio Frequency (RF) energy within the operating frequency band of the base station antenna 100 and the active antenna module 110. The radome 111 may be formed of, for example, fiberglass or plastic.

Still referring to fig. 2A, in some embodiments, the active antenna module 110 may be located behind the base station antenna 100 and may optionally be attached thereto. The base station antenna 100 may include a frame 112 and accessory mounting brackets 113, 114. The rear portion 111r of the housing 100h may be a planar surface extending along a common plane throughout its longitudinal extent or along at least a portion of its longitudinal extent.

Fig. 2B illustrates that the rear surface 100r may include a recessed and/or stepped segment 102 facing the active antenna module 110. The stepped segment 102 is closer to the front 100f of the housing than the rear wall defined by the main segment of the rear 100r of the housing 100h. The stepped segment 102 may have the same or a greater lateral and longitudinal extent than the lateral and longitudinal extent of the active antenna module 110. The rear surface 100r may also include a pair of spaced apart longitudinally extending rails 118 that engage the adapter mounting brackets 1118 on the active antenna module 110 to attach the active antenna module 110 to the base station antenna housing 100h. However, other mounting arrangements may be used.

Referring again to fig. 2A, in another embodiment, the rear surface 100r may include a plurality of longitudinally spaced mounting structure brackets, shown as an upper bracket 115, an inboard bracket 116, and a lower bracket 117, respectively, extending rearwardly from the housing 100 h. In some embodiments, the mounting structure brackets 115, 116, 117 may be configured to couple to one or more mounting structures, such as towers, poles, or buildings (not shown). At least two of the mounting structure brackets 115, 116 may also be configured to be attached to the frame 112 of the base station antenna arrangement in use. The frame 112 may extend over a sub-length of the longitudinal extent L of the base station antenna 100, wherein the sub-length is shown in fig. 2A as at least a major portion thereof (at least 50% of its length). The frame 112 may include a top 112t, a bottom 112b, and two opposing long sides 112s extending between the top 112t and the bottom 112 b. The frame 112 may have an open central space 112c extending laterally between the sides 112s and longitudinally between the top 112t and bottom 112 b.

In use, the frame 112 may be configured such that a variety of different active antenna modules 110 may be mounted to the frame 112 using appropriate accessory mounting brackets 113, 114. Thus, the various active antenna modules 110 may be interchangeably attached to the same base station antenna 100. Although a frame 112 is shown by way of example, other mounting systems may be used.

In some embodiments, multiple active antenna modules 110 may be attached to the same base station antenna 100 at the same time at different longitudinal locations using one or more frames 112. Such active antenna modules 110 may have different dimensions, e.g., different lengths and/or different widths and/or different thicknesses.

Turning now to fig. 3, an exemplary primary reflector 214 of the base station antenna 100 is shown. As shown, the primary reflector 214 has a first section 214 ₁ that extends a first longitudinal distance and merges into a second section 214 ₂ having spaced apart right and left side segments 214s having a lateral extent d2 that is less than the lateral extent d1 of the first section 214 ₁. The open medial region 14 may extend longitudinally and laterally around the second section 214 ₂. In some embodiments, the open medial region 14 may have a lateral extent d3 that is 60-95% of the lateral extent d 1. In some embodiments, the first section 214 ₁ may have a greater longitudinal extent than the second section 214 ₂, typically at least 20% greater, such as 30% -80% greater.

Fig. 4A and 4B illustrate an exemplary grid reflector 170 of the base station antenna 100. The grid reflector 170 includes a frequency selective surface and may be interchangeably referred to as a "frequency selective reflector" or a "frequency selective surface layer". The mesh reflector 170 may extend a portion or the entire lateral extent of the base station antenna 100 and at least a portion of the length of the base station antenna 100.

In some embodiments, the grid reflector 170 may be electrically and/or mechanically coupled to the primary reflector 214. In some embodiments, the grid reflector 170 may be positioned between the right and left sides 214s of the primary reflector in the open interior region 14 (fig. 3).

The grid reflector 170 may be provided as a non-metallic substrate in which the metallic patches are arranged to define an array 171 of unit cells (also interchangeably referred to as "pattern cells"), or may be a metallic grid and include an array 171 of unit cells.

The nonmetallic substrate may be provided as a multi-layer Printed Circuit Board (PCB), which may be rigid, semi-rigid, or provided as a flexible circuit. The nonmetallic substrate may be a plastic, a polymer, a copolymer with a metallized surface that provides a conductive patch.

The mesh reflector 170 may be provided as a thin (e.g., 5 mil) PCB attached to a dielectric, such as a polycarbonate matching layer or other suitable substrate. The grid reflector 170 may be defined by a thicker PCB (e.g., a 15 mil or 30 mil PCB).

The grid reflector 170 may be provided as a sheet of metal (e.g., aluminum) where the grid is shaped to form a pattern of cells/unit cells 171u (e.g., an array of unit cells 171), which may be etched, perforated, or laser formed or otherwise formed through the sheet of metal.

The grid reflector 170 provides a frequency selective surface and/or substrate configured to allow RF energy (electromagnetic waves) in one or more first defined frequency ranges to pass through and configured to reflect RF energy in a second, different frequency band. The frequency selective surface and/or substrate may be interchangeably referred to herein as "FSS". The grid reflector 170 of the base station antenna 100 may be located behind at least some of the antenna elements (see radiating elements 222 of fig. 31A, 31B) and may selectively reject some frequency bands and allow others to pass through by including a frequency selective surface and/or substrate to operate as a type of "spatial filter". See, e.g., ben A. Munk, frequency selective surface: theory and design (Frequency Selective Surfaces: theory AND DESIGN), ISBN:978-0-471-37047-5; DOI:10.1002/0471723770; month 4, 2000, copyright holderJohn Wiley & Sons, inc, the contents of which are incorporated herein by reference as if fully set forth herein.

The frequency selective surface of the grid reflector 170 and/or the substrate material may comprise one or more of a meta-material, a suitable RF material, or even air (although air may require more complex assembly). The term "meta-material" refers to a composite Electromagnetic (EM) material. The meta-material may include sub-wavelength periodic microstructures.

FSS170 may be provided as one or more collaboration layers. FSS170 may include a substrate having a dielectric constant in the range of about 2-4 (e.g., about 3.7) and a thickness of about 5 mils, and a metal pattern formed on the dielectric substrate. The thickness may vary, but thinner materials may provide lower losses.

In some embodiments, the frequency selective substrate/surface 170 may be configured to act as a high pass filter that substantially allows low band energy to be totally reflected (FSS may act as a metal sheet) while allowing higher band energy (e.g., about 3.5GHz or higher) to pass through completely. Thus, the frequency selective substrate/surface is transparent or invisible to higher band energy and a suitable out-of-band rejection response from the FSS can be achieved. The FSS material may allow for a reduction in filters, or even eliminate the filter requirement of the review radio 1120 (fig. 21A, 21B).

In some embodiments, FSS170 may be implemented, for example, using two or more closely spaced grids or FSS layers 170 ₁、170₂ stacked in the Z-direction, either or both of which may be provided as a multi-layer printed circuit board, wherein the different layers provide respective frequency selective surfaces configured to prevent electromagnetic waves within a predetermined frequency range from propagating through FSS layer 170 ₁、170₂ and to allow one or more other predetermined frequency ranges to pass through. Thus, the stacked FSS layers 170 ₁、170₂ may be spaced apart in the Z-direction and may cooperate to provide at least one rejection band and a (wider) passband.

Referring to fig. 4A and 4B, a grid (frequency selective) reflector 170 is shown according to an embodiment of the present disclosure. For example, the grid reflector 170 may be used in the base station antenna 10 shown in fig. 2A, 2B. The grid reflector 170 may include a body 21 and a frequency selective section 22 disposed in the body 21. At least the body 21 and/or the primary reflector 214 may be metallic (e.g., formed of aluminum). The frequency selection section 22 may be disposed at a position of the mesh reflector 170 corresponding to the installation position of the active antenna module 110 of the base station antenna 100, and may be configured to allow electromagnetic waves within a predetermined frequency range (e.g., high frequency electromagnetic waves within a 2300 to 5000MHz range or a portion thereof, e.g., electromagnetic waves within a 2900 to 4000MHz range or 3400 to 5000MHz range) to pass. In this way, when the base station antenna 100 is assembled, high frequency electromagnetic waves emitted by the active antenna module 110 may pass through the frequency selective reflector 20 via the frequency selective section 22.

The frequency selection section 22 may be constituted by an array 171 of a plurality of pattern units or unit units 171u arranged periodically in the lateral and longitudinal directions of the base station antenna. Each of the pattern units/unit units 171u may have a predetermined pattern, and may include a capacitor structure and an inductor structure connected in series (fig. 16A) or in parallel (fig. 16B) with the capacitor structure.

In addition, each pattern unit 171u of the array 171 may be electrically connected to each other through an inductor structure. For example, the inductor structures 2173 in each pattern unit/unit cell 171u may be electrically connected to the inductor structures 2173 of adjacent neighboring pattern units (fig. 9, 13).

The resonance frequency of the frequency selection section 22 may be configured by selecting or designing the pattern and size of the capacitor structure and the inductor structure of each pattern unit/unit cell 171 and the interval and arrangement of the plurality of pattern units 171 such that electromagnetic waves in a predetermined frequency range may pass through the frequency selection section 22.

Referring to fig. 5, an exemplary unit cell (or "pattern cell") 171u of an array or pattern 171 of unit cells of FSS170 is shown in accordance with an embodiment of the present disclosure. The unit cell 171u has a center 2171 and four linear segments 2172 extending orthogonally to each other, defining a "crisscross" pattern. Four linear segments 2172 protrude outward from the center 2171, and each of the four linear segments 2172 merges into a respective inductor feature 2173 extending laterally or longitudinally from a respective side 171s of the perimeter 171p of a respective unit cell 171u.

Each unit cell 171u may have a simple shape so as to have a small influence on both a small incident angle and a large incident angle. Positioning the inductor feature 2173 to extend adjacent each of the four outer perimeter sides 170s may provide improved performance at the operating frequency band, which may allow the inductance to be easily adjusted for the s-parameters of the operating frequency bands of different base station antennas 100. This inductor feature may also have a broadband feature.

Fig. 6 shows that the base station antenna 100 may include at least a first FSS layer 170 ₁ and a second FSS layer 170 ₂ stacked in the front-to-back (Z) direction, and each FSS layer may include an array 171 of unit cells.

Each FSS layer 170 ₁、170₂ may be spaced apart from one another by about 1/10-1/2 of the operating wavelength, for example about 1/4 of the operating wavelength of the high-band radiating element 1195 behind the second FSS170 ₂ or the low-band radiating element 222 in front of the first FSS layer 170 ₁. The term "operating wavelength" refers to a wavelength corresponding to the center frequency of the operating band of the radiating element (e.g., low band radiating element 222 or high band radiating element 1195). The spacing between FSS layers (e.g., 170 ₁ and 170 ₂) may be about 1/10-1/2 (typically 1/4) of the operating wavelength and is related to electrical length. For example, placement of higher dielectric constant (DK) materials therebetween may allow for smaller spacing.

In some embodiments, the first FSS170 ₁ and the second FSS170 ₂ may be located at a distance in the range of 1/10 wavelength to 1/2 wavelength of the operating wavelength in front of the high-band radiating element 1195.

Referring to fig. 7, the base station antenna 100 may include at least a first FSS layer 170 ₁, a second FSS layer 170 ₂, and a third FSS layer 170 ₃ that are closely spaced apart and stacked in a front-to-back (Z) direction, and each FSS layer may include an array 171 of unit cells. Each FSS layer 170 ₁、170₂、170₃ may be spaced apart from one another by about 1/10-1/2 of the operating wavelength, e.g., about 1/4 of the operating wavelength of the high-band radiating element 1195 behind the third FSS170 ₃ and/or the low-band radiating element 222 in front of the first FSS layer 170 ₁. The use of three or more FSS layers 170 ₁、170₂、170₃ may facilitate wider bandwidth and/or higher reflection at the low-frequency band. The use of three or more stacked FSS layers may provide greater/higher reflection at the low frequency band.

The two or three FSS structures of fig. 6 and 7 may be configured to have a passband for mMIMO radiating element 1195 (fig. 21A, 21B) including at least some frequencies in the range of, for example, 3150-5000MHz and 2200-4200MHz and all sub-bands therebetween, such as 2490-2690MHz, 3400-3980MHz and 2900-4000MHz.

Fig. 8 shows the unit cells 171u of each of the first FSS layer 170 ₁ and the second FSS layer 170 ₂ aligned in the X and Y directions, with the second FSS layer 170 ₂ behind the first FSS layer 170 ₁ (in the Z direction), the center 2171 of the front/first FSS layer 170 ₁ at substantially the same location as the center 2171 of the rear/second FSS layer 170 ₂, and the linear segments 2172 of each FSS layer 170 ₁、170₂ also aligned such that the linear segments 2172 of the front FSS170 ₁ are at substantially the same X-Y locations as the linear segments 2172 of the rear FSS170 ₂. Here, the term "substantially" means within +/-10% of each other in the X and/or Y directions.

The inductor feature 2173 ₂ of the second FSS layer 170 ₂ may be configured to have a different inductance value(s) than the inductor feature 2173 ₁ of the first FSS layer 170 ₁. The inductor features 2173 ₂ of the second FSS layer 170 ₂ may have inductor features of different sizes and/or different shapes, shown as having protrusions 2173p protruding laterally a distance dx or longitudinally a distance dy, further than the corresponding inductor features 2173 ₁ of the first FSS layer 170 ₁.

The inductor features 2173 may be configured to have different inductance values, which may depend on the distance of the respective FSS layer 170 ₁、170₂ from the front radome 100f and/or the rear radome 100r (fig. 2B) or the distance of the radome 119 of the AAU 110 (fig. 21A, 21B). The inductance value may also vary, for example, based on broadband operation when used for 5G operation, or based on whether positioned behind the low band radiating element 222 or the mid band radiating element 232, respectively (fig. 21A, 21B). The thickness and DK of radome(s) 111f and/or 119 can be key factors in selecting appropriate inductance values.

The inductor feature 2173 may be formed with symmetrical laterally extending protrusions 2173p on both sides 171s of the respective unit cell 171u and symmetrical longitudinally extending protrusions 2173p on the other two sides 171s of the respective unit cell 171u, wherein the protrusions 2173p extend around and opposite a virtual centerline C/L extending from and aligned with a corresponding linear segment 2172. The inductor features 2173 of each of the first FSS layer 170 ₁ and the second FSS layer 170 ₂ may extend a common distance from a distance spaced from the center 2171 to the perimeter 171p of the respective unit cell 171 u.

Fig. 9 shows two adjacent unit cells 171u1, 171u2 of each of the stacked first FSS layer 170 ₁ and second FSS layer 170 ₂. As shown, the first inductor structure 2173 ₁ a on the first FSS layer 170 ₁ is incorporated into the second inductor structure 2173 ₁ b at the common peripheral side 171s of the common 171 c. the second FSS layer 170 ₂ also provides respective first 2173 ₂ a and second 2173 ₂ b inductor structures connected at the common peripheral side 171s of the common 171c for adjacent unit cells 171u1, 171u 2. The first and second inductor structures 2173 ₂ a, 2173 ₂ b of the second FSS layer 170 ₂ have protrusions 2173p behind the first and second inductor structures 2173 ₁ a, 2173 ₁ b of the first FSS layer 170 ₁ and at X, X, Aligned with it in the Y-direction, but extending longitudinally beyond the boundaries of the corresponding protrusions 2173p on the first FSS layer 170 ₁. The other three sides 171s of the respective unit cells 171u1 and 171u2 may have similarly connected inductor structures 2173.

Fig. 10A shows another embodiment of an exemplary unit cell 171 u. In this embodiment, the center 2171 is surrounded by a shaped pattern 2176 that is symmetrical on four sides, having a curvilinear perimeter 2176p that merges into four linear segments 2172 that are orthogonal to each other and then into an inductor structure 2173. The shaping pattern 2176 may be a box pattern 2176b having four corners 2176 c.

Fig. 10A also shows a first FSS layer 170 ₁ in front of and over a second FSS layer 170 ₂ having a corresponding aligned unit cell 171 u. The shaping pattern 2176 ₂ surrounding the center 2171 on the second FSS layer 170 ₂ is aligned in the X-Y direction with the shaping pattern 2176 ₁ on the first FSS layer 170 ₁ such that it is "hidden" in the illustrated view by the shaping pattern 2176 on the first FSS layer 170 ₁.

Fig. 10B shows an alternative configuration of at least one of the FSS layers 170 with a unit cell 171u having an inductor structure 2173 and a shaped (metal) pattern 2176p surrounding a center 2171. In this embodiment, the shaped pattern 2176p is configured such that the box pattern 2176b is rotated 90 degrees from the orientation in fig. 10A, and the inductor structures are connected at respective corners, with each of the four inductor structures 2173 merging into a different one of the four corners 2176c of the box pattern 2176 b.

Referring to fig. 10C, the unit cell 171u may be arranged to provide a wideband FSS whose equivalent circuit 1700 includes a respective capacitor 2273 in parallel with a respective inductor 2173, thereby forming three LC circuits 2275, two of which have a pair of inductors in parallel with each other and the capacitor 2273, and a central LC circuit having a single LC circuit 2275 without the shunt inductor 2173a.

The circuit 1700 may provide a high pass filter and the inductance/inductor may be very small. Alternatively, the circuit 1700 may provide a low pass filter and the capacitor/capacitance may be very small. The inductance L and the capacitance C can be calculated by srf=1/2pi v LC. As known to those skilled in the art, "SRF" means "self-resonant frequency". In an antenna or circuit design, this frequency may be related to the middle/center frequency of the operating band.

Fig. 11 shows yet another embodiment of an exemplary unit cell 171 u. In this embodiment, four linear segments 2172 extend from center 2171 orthogonal to each other and again merge into an inductor structure 2173 having protrusions 2173p as discussed above with respect to other embodiments. In this embodiment, the inductor structure 2173 is located at a closer distance from the center 2171 and terminates before the outer peripheral side 171s such that there is an outer linear segment 2178 extending from the inductor structure 2173 to the outer peripheral side 170 s. In this embodiment, the inductor structures 2173 of adjacent unit cells 171u will be connected via external linear segments 2178. Thus, in this embodiment, four linear segments 2172 are inner linear segments, and one inductor structure 2173 may be located between each pair of outer 2178 and inner 2172 linear segments, respectively.

Fig. 12 shows another embodiment of an exemplary unit cell 171 u. In this embodiment, the inductor structures 2173 are positioned spaced around the perimeter of the unit cell 171 u. Perimeter 171p has linear segments 2172 that connect spaced-apart inductor structures 2173. A major portion, e.g., 60-95%, of the surface area of unit cell 171 (including center 2171) in the X-Y direction may be open and/or free of any metal or metal trace(s). Inductor structure 2173 has protrusions 2173p extending inwardly from perimeter 171 p. As shown, the linear segments 2172 stop at or merge into each end 2173e of the inductor structure 2173 such that they do not extend longitudinally or laterally at the location of the inductor structure 2173.

Referring to fig. 13, for adjacent unit cells 171u1, 171u2, the linear segment 2172 may be provided as a common linear segment 2172s at the outer peripheral side 170s of the common 171c, and the corresponding inductor structure 2173 ₁、2173₂ may protrude inwardly from the common linear segment 2172 s. The common side 170c is configured with two inductor structures 2173 ₁、2173₂ defining a parallel inductor circuit 2200 thereat.

Adjusting the inductance provided by inductor structure 2173 may provide good s-parameters for the operating frequency bands of various embodiments of base station antenna 100.

The parallel inductor circuit 2200 may be configured to provide the same inductance for the unit cell 171u as the single inductor 2173. For unit cells 171u disposed in a metal substrate or provided by a larger metal pattern, the reflection of the low frequency band may be greater/higher, but the passband s-parameter may be slightly reduced relative to the narrow metal traces on the dielectric layer.

Fig. 14 shows a circuit schematic based on an exemplary current direction of radiation projected in the Z-direction (fig. 15) through FSS layer 170 with unit cells 171 u. The capacitance is very small.

The unit cell 171u may be arranged to provide an equivalent circuit 1700 as shown in fig. 16A (a vertical equivalent circuit with a capacitor 2273 in series with an inductor 2173) and an equivalent circuit as shown in fig. 16B (a horizontal equivalent circuit between nodes a, B shown in fig. 14, in which the capacitor 2273 is connected in parallel with the inductor 2173, thereby forming an LC circuit). In fig. 16A, a circuit 1700 may provide a high pass filter with very small inductance/inductor. In fig. 16B, a circuit 1700 may provide a low pass filter with very small capacitors/capacitances. The inductance L and the capacitance C can be calculated by srf=1/2pi v LC. As known to those skilled in the art, "SRF" means "self-resonant frequency". In an antenna or circuit design, this frequency may be related to the middle/center frequency of the operating band.

In some embodiments, the unit cells 171 of one or more of the FSS layers 170 ₁、170₂、170₃ may be configured to provide an equivalent circuit of the high-pass filter in the vertical and horizontal directions, and the inductor structure 2173 may provide an open high-band current space. The high band current may pass through the inductor while the low band may be rejected.

Fig. 16C shows simulated wideband FSS response (db) versus frequency (GHz), e.g., m1-m4 parameters, for circuit 1700, i.e., horizontal equivalent circuit H (fig. 16B) and vertical equivalent circuit V (fig. 16A).

Fig. 16D shows a simulated response of the base sample LC circuit serving as a reference. The response frequency is f0 (about 2.5 GHz), m2 is the start of the bandpass, and m4 is the end of the bandstop.

Turning now to fig. 17a, the (equivalent unit cell) circuit 1700 of the fss170 may include a transmission ("TX") line segment 2373, which may be electrically coupled to an inductor 2173. As shown, inductor 2173 forms an LC circuit with capacitor 2273. The transmission line segment 2373 is connected in parallel with LC circuit 2275. The size of TX line segment 2373 may have a width dimension W, which may optionally be less than a length dimension L. TX line segment 2373 may be wider than microstrip trace segment 2375 on its opposite end. The length L may be about half the wavelength of the second response point f2 and the width W may be any value, as this is equivalent to L and C values. Depending on the target design, the width W may be configured (equal to the adjustment L/C) to achieve a high Q value and/or a low Q value.

In some particular embodiments, TX line segment 2373 may have a width dimension W in the range of 0.02mm to 0.2 mm. In some particular embodiments, the length dimension L may be in the range of 10-30mm, for example, about 22.6mm, in some embodiments.

In some embodiments, the length dimension L of TX line segment 2373 may be configured such that signals passing through TX line segment are subject to a 180 degree phase shift at defined frequency f 2. In some embodiments, the defined frequency f2 may be in a high-band range, for example, in a range between 3.5 and 6.5 GHz.

Fig. 17B shows a simulated response plot of the wideband FSS grid of the equivalent circuit 1700 shown in fig. 17A, i.e., a plot of frequency (GHz) versus decibel, with f0 and f2 and exemplary m1, m2, and m4 parameters. By adding an additional TX line segment 2373 in circuit 1700, a second response frequency point occurs and the total bandwidth can be extended. f2 is the second response frequency point.

Fig. 18A shows another exemplary equivalent circuit 1700 having a first transmission line segment 2373 ₁ and a second transmission line segment 2373 ₂ coupled to LC circuit 2275, one transmission line segment above and in parallel with LC circuit 2375 and one transmission line segment below and in parallel with LC circuit 2275. The two transmission line segments 2373 ₁、2373₂ may have a length dimension L, which in some embodiments may be shorter than the length dimension shown in fig. 17A, for example, about 17mm. The ultra-wideband FSS equivalent circuit 1700 may be configured such that the phase increases PH ₂ = arc tan (X/R), where X is a fixed imaginary number and R is a real number in the series circuit. Adding the second TX line segment 2373, the Q value of circuit 1700 may become lower and expand the bandwidth of the bandpass.

Fig. 18B shows a simulated response plot of the wideband FSS grid of the equivalent circuit 1700 shown in fig. 18A, i.e., a plot of frequency (GHz) versus decibel, with f0 and f2 and exemplary m1, m2, m3, and m4 parameters. As shown, f0 may be in the range of 2-3GHz, for example, about 2.5GHz, while f2 may be in the range of 4.5-6.5GHz, for example, a minimum of about 5.5 GHz.

Fig. 19A illustrates another example equivalent circuit 1700 having a first transmission line segment 2373 ₁ and a second transmission line segment 2373 ₂ coupled in series to a plurality of inductors 2173 (shown as first inductor 2173 ₁, second inductor 2173 ₂, and third inductor 2173 ₃). The second (intermediate) inductor 2173 ₂ may have a greater inductance than the end inductor 2173 ₁、2173₃. The unit cell (equivalent) circuit 1700 may include a capacitor 2273. The circuit 1700 may include a second capacitor 2273 ₂ in parallel with the first capacitor 2273 ₁. Both the first transmission line segment 2373 ₁ and the second transmission line segment 2373 ₂ may be on a common side (both shown above) and in parallel with the second capacitor 2273 ₂.

Fig. 19C shows the simulated response benchmark response of the equivalent circuit 1700 shown in fig. 19A, i.e., frequency (GHz) versus decibel, with f0 and f2 and exemplary m2, m4, and m6 parameters. As shown, f0 may be in the range of 2-3GHz, for example, about 2.5GHz, while f2 may be in the range of 3.5-5GHz, shown as about 4.5GHz.

Fig. 19B is a schematic diagram of a plurality of unit cells 171u of the grid reflector 170, whereby at least some of the unit cells 171u may be configured to have an equivalent circuit 1700 shown in fig. 19A.

Fig. 20A shows another exemplary equivalent circuit 1700 having a first transmission line segment 2373 ₁ and a second transmission line segment 2373 ₂ coupled to a plurality of inductors 2173. The inductor 2173 may be connected in series with the first capacitor 2273 ₁ therebetween. The circuit 1700 may include a second capacitor 2273 ₂ in parallel with the first capacitor 2273 ₁. The second capacitor 2273 ₂ may have a larger capacitance than the first capacitor 2273 ₁. Both the first transmission line segment 2373 ₁ and the second transmission line segment 2373 ₂ may be on a common side (both shown above) and in parallel with the capacitor 2273.

Fig. 20C shows the simulated response of the equivalent circuit 1700 shown in fig. 20A, i.e., frequency (GHz) versus decibel, with f0 and f2 and exemplary m2, m4, and m6 parameters. As shown, f0 may be in the range of 2-3GHz, for example, about 2.5GHz, while f2 may be in the range of 3.5-5GHz, shown as about 4.5GHz.

Fig. 20B is a schematic diagram of a plurality of unit cells 171u of the grid reflector 170, whereby at least some of the unit cells 171u may be configured to have an equivalent circuit 1700 shown in fig. 20A.

Fig. 21A shows another exemplary equivalent circuit 1700 having a first transmission line segment 2373 ₁ and a second transmission line segment 2373 ₂ coupled to a plurality of inductors 2173. In this embodiment, the inductor of fig. 19A and the capacitor of fig. 20A are omitted from the circuit. Thus, a first inductor 2173 ₁ is attached to a first end of TX line segment 2373 ₁、2373₂ and a second inductor 2173 ₂ is attached to an opposite second end of TX line segment 2373 ₁、2373₂. The circuit 1700 may include a capacitor 2273 coupled to the first inductor and the second inductor. The second capacitor 2273 ₂ may have a larger capacitance than the first capacitor 2273 ₁. Both the first transmission line segment 2373 ₁ and the second transmission line segment 2373 ₂ may be on a common side (both shown above) and in parallel with the capacitor 2273.

Fig. 21D shows a simulated response plot of the equivalent circuit 1700 shown in fig. 21A, i.e., a plot of frequency (GHz) versus decibel, with f0 and f2 and exemplary m1, m2, m4, and m6 parameters. As shown, f0 may be in the range of 2-3GHz, for example, about 2.5GHz, while f2 may be greater than f0 and in the range of 3.5-5GHz, shown as about 4.5GHz.

Fig. 21B is a schematic diagram of a plurality of unit cells 171u of the grid reflector 170, whereby at least some of the unit cells 171u may be configured to have an equivalent circuit 1700 shown in fig. 21A. A single-layer copper printed circuit board may provide the unit cells 171u. Fig. 21C is an enlarged portion of the unit cell shown in fig. 21B, which shows parallel adjacent traces 2373L forming part of the unit cell 171u. Parallel lines 2373L may be used for TX line segments 2373 and may be configured such that a layer of copper or other conductive metal may be used for unit cells 171u.

Fig. 22A illustrates another example of a wideband FSS using a dual layer FSS configuration that can be electrically coupled and stacked in a front-to-back direction, each layer 170 ₁、170₂ including cooperating components that together form an equivalent circuit 1700. Each layer 170 ₁、170₂ includes a unit cell 171u in which a first transmission line segment 2373 ₁ and a second transmission line segment 2373 ₂ are coupled to a plurality of inductors 2173. Each layer 170 ₁、170₂ may include unit cells 171u having the same configuration of the equivalent circuit 1700. In this embodiment, as discussed with respect to fig. 21A, a first inductor 2173 ₁ is attached to a first end of TX line segment 2373 ₁、2373₂ and a second inductor 2173 ₂ is attached to an opposite second end of TX line segment 2373 ₁、2373₂. The circuit 1700 may include a capacitor 2273 coupled to the first inductor and the second inductor. The second capacitor 2273 ₂ may have a larger capacitance than the first capacitor 2273 ₁. Both the first transmission line segment 2373 ₁ and the second transmission line segment 2373 ₂ may be on a common side (both shown above) and in parallel with the capacitor 2273.

Fig. 22C shows a simulated response plot of the equivalent circuit 1700 shown in fig. 22A, i.e., a plot of frequency (GHz) versus decibel, with f0 and exemplary m1, m2, and m6 parameters. As shown, f0 may be in the range of 2-3GHz, for example, about 2.5GHz.

Fig. 22B is a schematic diagram of a plurality of unit cells 171u of the first layer 170 ₁ and the second layer 170 ₂ of the grid reflector, whereby at least some of the unit cells 171u of each layer may be configured with the equivalent circuit 1700 shown in fig. 22A.

Fig. 23A illustrates another example of a wideband FSS using a dual layer FSS configuration that can be electrically coupled and stacked in a front-to-back direction, each layer 170 ₁、170₂ including components that form an equivalent circuit 1700. Each layer 170 ₁、170₂ includes a unit cell 171u in which a first transmission line segment 2373 ₁ and a second transmission line segment 2373 ₂ are coupled to a plurality of inductors 2173. each layer 170 ₁、170₂ may include unit cells 171u having different equivalent circuit 1700 configurations. In this embodiment, first layer 1701 includes equivalent circuit 1700 with first inductor 2173 ₁ attached to a first end of TX line segment 2373 ₁、2373₂ and second inductor 2173 ₂ attached to an opposite second end of TX line segment 2373 ₁、2373₂. The circuit 1700 may include a capacitor 2273 coupled to the first inductor 2173 ₁ and the second inductor 2173 ₂. The second capacitor 2273 ₂ may have a larger capacitance than the first capacitor 2273 ₁. Both the first transmission line segment 2373 ₁ and the second transmission line segment 2373 ₂ may be on a common side (both shown above) and in parallel with the capacitor 2273. The second layer 170 ₂ may have an equivalent circuit 1700 that includes an LC circuit 2275 coupled to the equivalent circuit provided by the first layer 170 ₁.

Fig. 23C shows a simulated response plot of the equivalent circuit 1700 shown in fig. 23A, i.e., a plot of frequency (GHz) versus decibel, with f0 and exemplary m1, m2, and m6 parameters. As shown, f0 may be in the range of 2-3GHz, for example, about 2.5GHz, while f2 may be larger, for example, in the range of about 3.5-5GHz, shown as about 4.5GHz.

Fig. 23B is a schematic diagram of the unit cells 171u of the first layer 170 ₁ and the second layer 170 ₂ of the grid reflector closely stacked in the Z or front-to-back direction, whereby at least some of the unit cells 171u of each layer may cooperate to form the equivalent circuit 1700 shown in fig. 23A.

Fig. 24A shows another example of a wideband FSS using a dual-layer FSS configuration, each mesh FSS layer 170 ₁、170₂ including unit cells 171u forming part of at least one equivalent circuit 1700, which may be electrically coupled and stacked behind the front radome 111f of the base station antenna 100 in the front-to-back direction (fig. 2A).

Fig. 24B is a front view of the top layer 170 ₁ shown in fig. 24A, which illustrates that the mesh layer 170 ₁ may have cut-out regions 1170 of material extending within and/or around respective unit cells 171 u.

In some particular embodiments, one or both of the layers 170 ₁、170₂ may optionally be formed of a low dielectric constant (e.g., DK in the range of 1-4, more typically 2-4) material.

The main material of the substrate(s) providing the plurality of unit cells 171u may optionally include a low dielectric constant (DK) material. To change the LC value in the equivalent circuit 1700, this can be done by changing the size of the metal of the host material and the size of the cut-out region, and can include high DK material properties.

Fig. 25A shows an equivalent circuit 1700 with an inductor structure 2173 and a capacitor 2273 forming an LC circuit 2275. Fig. 25B illustrates a metamaterial and/or surface 1171 that may be configured to execute the circuit 1700 shown in fig. 25A. Fig. 25C illustrates a dielectric material selected to perform at least a portion of the circuit 1700 illustrated in fig. 25A. The L/C value of the inductor 2173 structure and capacitor 2273 of fig. 25A may be selected based on operational requirements and/or implementation (e.g., FSS layer 170 ₁、170₂ shown in fig. 24A).

The dielectric material need not be a low DK material. For example, if the configuration of FSS layer 170 ₁、170₂ shown in fig. 24A, for example, requires a different L/C, and that L/C may be provided by a high DK dielectric material, then a high DK dielectric material may be used in the FSS layer shown in fig. 24A.

It should be noted that if DK is too high to be obtained or expensive, then a super surface option, such as that shown in fig. 25B, may be used. The metamaterial 1171 may comprise adjacent segments separated by a cut segment providing a very small capacitance 2273, and the metamaterial 1171 may provide an inductance.

It should be noted that although the unit cells 171u are shown in some figures as having square perimeters, other shapes may be used. Different "sides" may be provided based on shape, for example, circular unit cells 171u may have circumferentially spaced apart inductor structures extending around a perimeter extending radially from the center. The unit cells 171u may have various shapes, such as triangle, rectangle, diamond, pentagon, hexagon, circle, ellipse, etc., and combinations of different shapes for different unit cells.

It should be noted that larger inductors or inductors with larger inductances may be provided on either the front FSS layer 170 ₁ or the rear FSS layer 170 ₂, depending on the application/use. In addition, the array 171 of unit cells may be provided with unit cells 171u of different shapes or densities at different positions (see fig. 26, 27, 28).

Referring to fig. 26, 27 and 28, the mesh reflector 170 may be configured such that there are different densities of unit cells 171u at different positions. In some embodiments, the grid reflector 170 may be configured such that the unit cells 171u may be asymmetric about one or more axes, for example, to improve cross-polarization performance.

Fig. 26 shows that the array 171 of unit cells 171u may be arranged with a greater density of unit cells 171u at the left and right portions 170r, 170l relative to the inner portion 170 m. Fig. 26 also shows that the unit cells 171 located at the inner portion 170m of the grid reflector 170 may have a larger surface area, height and/or width than the unit cells 171u located at the left and right portions 170r, 170l, shown as a common height dimension and different width dimensions and having a larger central space 172.

Fig. 27 shows a greater density of unit cells 171u at the inner portion 170m of the grid reflector 170 relative to unit cells 171u at the right portion 170r and/or the left portion 170 l. Fig. 27 also shows that the unit cells 171 at the right and left side portions 170r, 170l may have a larger surface area, height and/or width than the unit cells 171 at the inner side portion 170m, shown as a common height and larger width and having a larger central space 172.

Fig. 28 shows that the frequency selective surface of the grid reflector 170 may have different shaped unit cells 171u in different regions. In some embodiments, the inner portion 170m of the grid reflector 170 may include square unit cells 171u, while the right and left sides 170r and 170l, respectively, may have hexagonal unit cells 171u. These unit cells 171u of different shapes may be disposed on one mesh reflector or on the first and second mesh reflectors 170 ₁ and 170 ₂ stacked in the front-rear (Z) direction. Fig. 29A shows that the hexagonal shape of unit cells 171u may be a solid (metal) patch, while fig. 29B shows that the hexagonal shape of unit cells 171u may be arranged as a hexagonal ring around an open center or the center of a different (non-conductive) material.

Thus, as shown in fig. 26, 27 and 28, the first mesh reflector 170 ₁ may have an array 171 of unit cells, where a first subset of the unit cells 171u are tuned to block and/or reflect RF energy in a first frequency band while allowing RF energy in a second frequency band to propagate through the first mesh reflector, and a second subset of the unit cells 171u are tuned to block and/or reflect RF energy in the first frequency band and RF energy in a third frequency band. The third frequency band includes frequencies between the first frequency band and the second frequency band.

The first subset 171a of the unit cells 171u may be positioned at an upper portion of the base station antenna 100. The second subset 171b of unit cells 171u may include unit cells below and/or to the right and left of the first subset 171a of unit cells 171 u.

The first subset 171a of unit cells 171 may be located behind the low-band radiating elements 222 and in front of the high-band radiating elements 1195 (e.g., mMIMO array) and/or the dual-band radiating elements. The second subset 171b of unit cells 171 may be located behind the mid-band radiating element 232. The first frequency band may be a low frequency band, the second frequency band may be a high frequency band, and the third frequency band may be a medium frequency band, with at least some frequencies between the first frequency and the second frequency.

The first subset of unit cells 171u may be positioned at an upper portion of the base station antenna 100. The second subset 171b of the unit cells 171 may include unit cells below and/or to the right and left of the first subset 171a of the unit cells 171. Some of the unit cells 171u in the second subset 171b of the unit cells 171 may be on the left and/or right side of the first subset 171a of the unit cells.

The first subset 171a of unit cells 171 may be located behind the low-band radiating elements 222 and in front of the high-band radiating elements 1195 (e.g., mMIMO array). The second subset 171b of unit cells 171 may be located behind the mid-band radiating element 232.

The first FSS layer/first mesh reflector 170 ₁ may be configured to merge into or attach to the longitudinally extending right and left sides 214s of the (substantially solid) surface of the primary reflector 214 at one or more locations, for example, along the longitudinally extending outer side. As discussed above, the grid reflector 170 may be configured to have different unit cell configurations and/or sizes at different locations.

In some embodiments, the first FSS layer/first mesh reflector 170 ₁ of the passive antenna assembly 190 may be configured to act as a high pass filter that substantially allows low band energy to be fully reflected while allowing higher band energy (e.g., about 3.5GHz or higher) to pass, typically substantially fully, when the mesh is formed from sheet metal.

The first FSS layer 170 ₁ and the second FSS layer 170 ₂ may be transparent or invisible to higher band energy and may cooperate to provide a suitable out-of-band rejection response that may be achieved.

Turning now to fig. 30A, 30B, an exemplary passive antenna assembly 190 is shown. The first FSS layer/first mesh reflector 170 ₁ may be incorporated into the longitudinally and laterally extending main reflector 214. The primary reflector 214 may have a longitudinal length that is greater than the longitudinal length of the first grid reflector 1701. The main reflector 214 may have a solid reflective surface for the antenna element located in front of the main reflector 214 and may be located above the operating component 314 (e.g., filter, tilt adjuster, etc.).

In some embodiments, the first mesh reflector 170 ₁ may be located at a distance in the range of 1/8 wavelength to 1/4 wavelength of the operating wavelength behind the low-band dipole 222. As discussed above, the term "operating wavelength" refers to a wavelength that corresponds to the center frequency of the operating band of the radiating element (e.g., low band radiating element 222). In some embodiments, the first mesh reflector 170 ₁ may be located at a distance in the range of 1/10 wavelength to 1/2 wavelength of the operating wavelength in front of the high-band radiating element 1195. For example, in certain particular embodiments, the first mesh reflector 170 ₁ may be located a physical distance of 0.25 inches and 2 inches from a ground plane or reflector 1172 behind the mMIMO array of radiating elements 1195 of the active antenna module 110 (fig. 31A, 31B). Other placement locations may be used.

In some embodiments, the ground plane or reflector 1172 of the active antenna module 110 may be electrically coupled to the first mesh reflector 170 ₁ and/or the main reflector 214 of the base station antenna 100, e.g., galvanic coupling and/or capacitive coupling. In other embodiments, the ground plane or reflector 1172 of the active antenna module 110 is not electrically coupled to the first mesh reflector 170 ₁ and/or the main reflector 214.

Referring to fig. 30A, the first mesh reflector 1701 may have a longitudinal extent "L" and a lateral extent "W". The longitudinal extent L may extend a distance greater than the lateral extent W. The longitudinal extent L may be less than the lateral extent W. The first mesh reflector 170 ₁ has a front side 170f facing the front side 100f of the housing 100 h/radome 111.

The antenna assembly 190 includes a plurality of arrays of radiating elements, typically arranged in six columns, with the radiating elements extending forward from the front side 170f of the first FSS layer 170 ₁, with some columns of radiating elements continuing to extend forward of the primary reflector 214. Each array of radiating elements of the antenna assembly 190 may include radiating elements 222 configured to operate in a first frequency band and radiating elements 232 configured to operate in a second frequency band. Other arrays of radiating elements may include radiating elements configured to operate in a second frequency band or a third frequency band. The first frequency band, the second frequency band, and the third frequency band may be different frequency bands (although may overlap). In some embodiments, the low band antenna element 222 with dipole arms may be located in front of the grid reflector 170, generally along the right and left portions 170s and/or the main reflector side 214s of the grid reflector 170.

In some embodiments, the first FSS layer/mesh reflector 170 ₁ and the primary reflector 214 may be integrally formed as a unitary (sheet-like) metal body. Alternatively, the first mesh reflector 1701 and the main reflector 214 may be provided as separate components that are directly or indirectly attached and electrically coupled together to provide a common electrical ground. The first mesh reflector 1701 and the main reflector 214 may both be sheet metal of the same or different thickness. The first mesh reflector 170 ₁ may be disposed as a printed circuit on a dielectric substrate and the main reflector 214 may be a metal sheet.

In some embodiments, the first FSS layer and the second FSS layer 170 ₁、170₂ may each be provided as a printed circuit board in which the conductive traces form an array 171 of unit cells. The first mesh reflector and/or the second mesh reflector 170 ₁、170₂ may be provided as a flexible circuit board having the unit cells 171u. The first mesh reflector and/or the second mesh reflector 170 ₁、170₂ may be provided as a non-metallic substrate in which the metallized traces form the unit cells 171u.

Some radiating elements (discussed below) of antenna 100 may be mounted to extend forward from primary reflector 214, and if dipole-based radiating elements are used, the dipole radiators of these radiating elements may be mounted in front of primary reflector 214 approximately 1/4 of the wavelength of the operating frequency of each radiating element. The primary reflector 214 may serve as a reflector and ground plane for the radiating elements of the base station antenna 100 mounted thereon.

Still referring to fig. 30A, 30B, the passive antenna assembly 190 of the base station antenna 100 may include one or more arrays 220 of low band radiating elements 222, one or more arrays 230 of first mid band radiating elements 232, one or more arrays 240 of second mid band radiating elements 242, and one or more arrays 250 of optional high band radiating elements 252. The radiating elements 222, 232, 242, 252, 1195 may each be dual polarized radiating elements. Additional details of radiating elements can be found in WO2019/236203 and WO2020/072880, the contents of which are incorporated herein by reference as if fully set forth herein. Some of the high-band radiating elements, such as radiating element 1195, may be provided as mMIMO antenna arrays and may be provided in the active antenna module 110 instead of in the housing 100h of the base station antenna 100.

The low-band radiating elements 222 may be mounted extending forward from the primary or main reflector 214 and the first FSS layer 170 ₁, and may be mounted in two columns to form two linear arrays 220 of low-band radiating elements 222. In some embodiments, each low-band linear array 220 may extend along substantially the entire length of the antenna 100.

The low band radiating element 222 may be configured to transmit and receive signals in a first frequency band. In some embodiments, the first frequency band may include a 617-960MHz frequency range or a portion thereof (e.g., 617-896MHz band, 696-960MHz band, etc.). The low-band linear array 220 may or may not be used to transmit and receive signals in the same portion of the first frequency band. For example, in some embodiments, the low-band radiating elements 222 in the first linear array 220 may be used to transmit and receive signals in the 700MHz band, and the low-band radiating elements 222 in the second linear array 220 may be used to transmit and receive signals in the 800MHz band. In other embodiments, the low band radiating elements 222 in both the first linear array 220-1 and the second linear array 220-2 may be used to transmit and receive signals in the 700MHz (or 800 MHz) frequency band.

The first mid-band radiating element 232 may likewise be mounted to extend forward from the primary reflector 214 and/or the first FSS layer 170 ₁, and may be mounted in multiple columns to form a linear array 230 of first mid-band radiating elements 232. The linear array 230 of mid-band radiating elements 232 may extend along respective side edges of the first FSS layer 170 ₁ and/or the primary reflector 214. The first mid-band radiating element 232 may be configured to transmit and receive signals in the second frequency band. In some embodiments, the second frequency band may include the 1427-2690MHz frequency range or a portion thereof (e.g., 1710-2200MHz band, 2300-2690MHz band, etc.). In the depicted embodiment, the first mid-band radiating element 232 is configured to transmit and receive signals in a lower portion of the second frequency band (e.g., some or all of the 1427-2200MHz frequency band). The linear array 230 of first mid-band radiating elements 232 may be configured to transmit and receive signals in the same portion of the second frequency band or in different portions of the second frequency band.

The second mid-band radiating elements 242 may be mounted in a plurality of columns to form a linear array of second mid-band radiating elements 242. The second mid-band radiating element 242 may be configured to transmit and receive signals in a second frequency band. In the depicted embodiment, the second mid-band radiating element 242 is configured to transmit and receive signals in an upper portion of the second frequency band (e.g., some or all of the 2300-2700MHz frequency band). In the depicted embodiment, the second mid-band radiating element 242 may have a different design than the first mid-band radiating element 232.

The high-band radiating elements 252 and/or 1195 may be mounted in columns in an upper inner side or center portion of the antenna 100 to form a multi-column (e.g., four or eight columns) array 250 of high-band radiating elements 252 and/or 1195. The high-band radiating element 1195 may be configured to transmit and receive signals in a third frequency band. In some embodiments, the third frequency band may include the 3300-4200MHz frequency range or a portion thereof.

In the depicted embodiment, the array 220 of low-band radiating elements 222, the array 230 of first mid-band radiating elements 232, and the array of second mid-band radiating elements 242 are all part of the passive antenna assembly 190, while the array 250 of high-band radiating elements 1195 are part of the active antenna module 110. It should be appreciated that in other embodiments, the type of array included in the passive antenna assembly 190 and/or the active antenna module 110 may vary.

It will also be appreciated that the number of linear arrays of low band, mid band and high band radiating elements may be different from that shown in the figures. For example, the number of linear arrays of radiating elements of each type may be different from that shown, some types of linear arrays may be omitted and/or other types of arrays may be added, the number of radiating elements of each array may be different from that shown, and/or the arrays may be arranged differently. As a specific example, the two linear arrays of second mid-band radiating elements 242 may be replaced with four linear arrays of ultra-high band radiating elements that transmit and receive signals in the 5GHz band.

At least some of the low band radiating element 222 and the mid band radiating elements 232, 242 may each be mounted to extend forward from and/or extend from the first FSS layer 170 ₁ or the primary reflector 214.

Each array 220 of low band radiating elements 222 may be used to form a pair of antenna beams, one for each of two polarizations at which dual polarized radiating elements are designed to transmit and receive RF signals. Likewise, each array 232 of first mid-band radiating elements 232 and each array of second mid-band radiating elements 242 may be configured to form a pair of antenna beams, one for each of the two polarizations at which dual polarized radiating elements are designed to transmit and receive RF signals. Each linear array may be configured to provide service to a sector of a base station. For example, each linear array 220, 230 may be configured to provide approximately 120 ° of coverage in the azimuth plane, such that the base station antenna 100 may be used as a sector antenna for a three-sector base station. Of course, it will be appreciated that the linear array may be configured to provide coverage over different azimuth beamwidths. While all of the radiating elements 222, 232, 242, 252, 1195 may be dual polarized radiating elements in the depicted embodiment, it should be appreciated that some or all of the dual polarized radiating elements may be replaced with single polarized radiating elements in other embodiments. It should also be appreciated that while the radiating elements are shown in the depicted embodiment as dipole radiating elements, other types of radiating elements may be used in other embodiments, such as, for example, patch radiating elements.

Some or all of the radiating elements 222, 232, 242, 252, 1195 may be mounted on feed boards that couple RF signals into and out of the respective radiating elements 222, 232, 242, 252, 1195, with one or more radiating elements 222, 232, 242, 252, 1195 mounted on each feed board. Cables (not shown) and/or connectors may be used to connect each feed plate to other components of the antenna 100, such as a diplexer, phase shifter, calibration plate, and the like.

An RF connector or "port" 140 (fig. 2A) may be mounted in bottom end cap 130 for coupling RF signals from an external remote radio unit (not shown) to the array of passive antenna assemblies 190. Two RF ports may be provided for each array, a first RF port 140 coupling a first polarized RF signal between the remote radio unit and the array and a second RF port 140 coupling a second polarized RF signal between the remote radio unit and the array. Since the radiating elements 222, 232, 242 may be tilted cross dipole radiating elements, the first polarization and the second polarization may be-45 ° polarization and +45° polarization.

The phase shifter may be connected into the RF port 140. The phase shifter may be implemented, for example, as a brush arc phase shifter, such as disclosed in U.S. patent No. 7,907,096 to Timofeev, the disclosure of which is incorporated herein in its entirety. The mechanical linkage may be coupled to a RET actuator (not shown). The RET actuator may apply a force to a mechanical linkage, which in turn adjusts a movable element on the phase shifter to electronically adjust the downtilt angle of an antenna beam generated by one or more of the low-band or mid-band linear arrays.

It should be noted that a multi-connector RF port (also referred to as a "cluster" connector) may be used instead of the individual RF ports 140. Suitable cluster connectors are disclosed in U.S. patent application Ser. No. 16/375,530, filed on 4.4.2019, the entire contents of which are incorporated herein by reference.

The radiating element 220 may be a dipole element configured to operate in some or all of the 617-960MHz band. A feeding circuit including a hook balun may be provided on the feeding stem 221 (fig. 30B). Additional discussion of exemplary antenna elements including antenna elements (including feed handles) may be found in U.S. patent application Ser. No. 17/205,122, the contents of which are incorporated herein by reference as if fully set forth herein.

Turning now to fig. 31A, 31B, an exemplary active antenna module 110 is shown. The active antenna module 110 may include an RRU (remote radio unit) unit 1120 with radio circuitry. The active antenna module 110 may also include a filter and calibration printed circuit board assembly (not shown) and an antenna assembly 1190 including a reflector or ground plane for the printed circuit board 1172 behind the radiating element 1195. The antenna assembly 1190 may also include a phase shifter (not shown) that may alternatively be part of the filter and calibration assembly. Radiating element 1195 may be configured as a massive MIMO array. RRU unit 1120 is a radio unit that typically includes radio circuitry that converts base station digital transmissions into analog RF signals (and vice versa). One or more of the radio unit or RRU unit 1120, the antenna component 1190, or the filter and calibration components may be provided as separate sub-units that are attachable (stackable). The RRU unit 1120 and the antenna assembly 1190 may be provided as an integrated unit, optionally also including a calibration assembly 1180. Where configured as a subunit, the different subunits may be provided by an OEM or cellular service provider while still using the common base station antenna housing 100h and its passive antenna components 190. In other embodiments, the radio circuitry may be provided as a single integrated unit with the antenna assembly.

Fig. 31A shows that the rear portion 100r of the base station antenna 100 may have a planar surface and the active antenna assembly 1190 may be configured to face the rear portion 100r with the radomes 119, 100r therebetween and the first and second FSS layers 170 ₁、170₂ in front of the radiating element 1195. Fig. 21B illustrates that the rear portion 100r of the base station antenna 100 may have a recessed section 102 and be sized to receive the radome 119 of the active antenna unit 110, again with the radiating element 1195 behind and facing the FSS layer 170 ₁、170₂.

Fig. 32A-32F illustrate additional exemplary embodiments of stacked FSS layers 170 ₁、170₂ spaced apart in the fore-aft direction of the base station antenna 100. An array of radiating elements 1195 may be positioned behind the first FSS layer 170 ₁ and the second FSS layer 170 ₂, typically in the active antenna module 110. The array of radiating elements 1195 may include an array mMIMO of radiating elements as discussed herein above.

The array of radiating elements may be provided as a dual band radiating element 1195d, where a first column of radiating elements in a first column projects forward a first distance and operates in a first frequency band, and a second column of radiating elements in a second column projects forward a smaller distance and operates in a second frequency band than the first column, and the unit cell in front of the first column may have a different configuration than the unit cell in front of the second column of radiating elements (fig. 32G).

Referring to fig. 32C, 32D, 32E, and 32F, the first FSS layer 170 ₁ may include a plurality of spaced apart cuts 1201. The feed plate 1200 may extend across/along these cutouts 1201 and the feed stem 222f may connect the radiating element 222 to the feed plate 1200. In some embodiments, the feed plate 1200 may be located behind the major front surface 170f of the reflector 170 ₁ and may include conductive (e.g., copper ground plane patterned surfaces/circuitry). The radiating element 222 may be provided in different configurations and is not limited to the configuration shown.

Fig. 32A, 32F, 32G illustrate that at least one of the first FSS layer 170 ₁ and the second FSS layer 170 ₂ may have a forward/rearward extending portion having unit cells 171u defining at least a portion of the sidewall 170 w. The respective sidewalls 170w may be metallic or provided as a printed circuit board or a combination thereof. The sidewall 170w may be a curved portion of one or more of the first FSS layer 170 ₁ and the second FSS layer 170 ₂. The sidewalls 170w may provide structural support for the reflector 170 and/or the radiating element 222 mounted thereto. The side wall 170w may also or alternatively be configured to improve the radiation pattern provided by one or more of the radiating elements 222 and/or the radiating elements 1195 in front of and/or behind the reflector 170 ₁、170₂.

The first/front FSS layer 170 ₁ may lie in a common plane with the primary reflector 214 (front-to-back position aligned with the primary reflector 214).

One or both of the first FSS170 ₁ layer and the second FSS170 layer ₂ may be configured such that the grid pattern extends across its entire lateral extent. In other embodiments, the grid pattern may be arranged/terminated at or coupled with the feed plate 1200 or its actual metallic surface.

Fig. 32B, 32E illustrate that the first FSS layer 170 ₁ and the second FSS layer 170 ₂ can be provided on the non-curved side. For example, one or both of the FSS layers 170 ₁、170₂ may be coupled to an internal mounting structure, such as a laterally extending and/or longitudinal rail, to position them in alignment in the base station antenna 100. One or both of the first FSS layer 170 ₁ and the second FSS layer 170 ₂ may be coupled to a surface of a radome or housing provided by the base station antenna 100.

Referring to fig. 32A, 32F, and 32G, the side wall 170w may be solid metal (e.g., solid sheet metal), or may have apertures 170a or cutouts between bar segments extending behind and/or in front of the front major surface 170F of the grid reflector 170.

As also shown in fig. 32G, the sidewalls 170w may extend forward and rearward of the front surface 170f of the first FSS layer 170 ₁ and/or the second FSS layer 170 ₂, shown as extending forward and rearward of the front/first FSS layer 170 ₁, orthogonal thereto.

At least a portion of the side wall 170w may be provided by a metal mesh or otherwise configured to provide an isolation surface/wall or FSS, e.g., metallic, metallized, or provided as a frequency selective surface/substrate.

As shown in fig. 32G, the sidewall(s) 170w may have a front section 170wf extending forward of the reflector 170 f. The sidewall(s) 170w may also have a rear/rear section 170wb extending rearward of the front section, with the front of the reflector extending laterally between the rear/rear section and the front section. The front section 170wf may have a different configuration than the rear section 170 wb. In some embodiments, the front section 170wf may be solid metal or formed of FSS. The posterior/posterior segment 170wb may be solid with apertures 170a and/or a grid pattern 171.

Fig. 32A, 32B, and 32E illustrate a base station antenna 100 including three stacked FSS layers 170 ₁、170₂、170₃.

The first FSS layer 170 ₁ and the second FSS layer 170 ₂ may be spaced apart by a distance "h" defined by the front-to-back dimension. In some embodiments, the distance "h" may be in the range of 5-50mm, such as about 20mm.

The distance "h" may correspond to a distance of 0.05-0.5 wavelength corresponding to the highest operating wavelength of the radiating elements in front of or behind one or both of the FSS layers 170 ₁、170₂.

Embodiments of the present invention have been described above with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

It will be understood that when an element is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present. It will also be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a similar fashion (i.e., "between" and "relative" directly between "and" between "," adjacent "and" relative "directly adjacent", etc.).

Relative terms, such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" may be used herein to describe one element, layer or region's relationship to another element, layer or region as illustrated in the figures. It will be understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.

The term "about" as used with respect to a number refers to a variation of +/-10%.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes" and/or "having," when used herein, specify the presence of stated features, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, operations, elements, components, and/or groups thereof.

Aspects and elements of all embodiments disclosed above may be combined in any manner and/or with aspects or elements of other embodiments to provide multiple additional embodiments.

Claims

1.A base station antenna, comprising:

A first Frequency Selective Surface (FSS) comprising a first array of unit cells, and

A second FSS comprising a second array of unit cells,

Wherein the first FSS is stacked in front of the second FSS in the base station antenna in the Z-direction, wherein each unit cell in the first array of unit cells and each unit cell in the second array of unit cells comprises a plurality of spaced apart inductor structures, and wherein a first unit cell in the first array of unit cells is aligned with a first unit cell in the second array of unit cells in the X-Y direction, whereby a respective inductor structure of the first unit cell is aligned with a respective inductor structure of a first unit cell in the second array of unit cells.

2. The base station antenna of claim 1, wherein a first unit cell in the first array of unit cells comprises a perimeter, wherein a first adjacent unit cell and a second adjacent unit cell share a perimeter side, and wherein inductor structures of the first adjacent unit cell and the second adjacent unit cell are electrically connected.

3. The base station antenna of claim 1, wherein the inductor structures of the first unit cells in the first array and the first unit cells in the second array are arranged as curvilinear projections on or adjacent to the outer periphery of the respective first unit cells.

4. The base station antenna of claim 1, wherein a first of the first array of unit cells and a second of the unit cells each comprise a center and four linear segments protruding outward from the center, wherein the four linear segments are orthogonal to each other, and wherein the four linear segments each merge into at least one inductor structure of their respective inductor structures.

5. The base station antenna of claim 4, wherein the respective inductor structure of each unit cell comprises protrusions protruding serially outward from opposite sides of a lateral or longitudinal centerline of the corresponding linear segment, and wherein the protrusions of the inductor structure of a first unit cell in the second array extend outside the boundaries of the protrusions of a first unit cell in the first array of unit cells.

6. The base station antenna of claim 1, wherein the inductor structures of adjacent unit cells in the first array of unit cells define parallel inductor circuits.

7. The base station antenna of claim 1, wherein one inductor structure of a first unit cell in the first array of unit cells merges into one inductor structure of an adjacent second unit cell in the first array of unit cells at a common perimeter side.

8. The base station antenna of claim 1, wherein the inductor structure is located only on a perimeter of a respective unit cell in each of the first array of unit cells and the second array of unit cells.

9. The base station antenna of claim 4, wherein a first unit cell of the first array of unit cells and the second array of unit cells further comprises a curved section around the center, and wherein the four linear sections extend from four sides of the curved section around the center.

10. The base station antenna of claim 4, wherein the four linear segments are inner linear segments, wherein the first unit cell further comprises four outer linear segments, and wherein one of the inductor structures is located between a pair of outer and inner linear segments.

11. The base station antenna of claim 1, further comprising a third FSS located after the second FSS, the third FSS having a third array of unit cells.

12. The base station antenna of claim 1, further comprising a passive antenna having the first FSS and the second FSS in a housing, and an active antenna unit located behind the housing.

13. The base station antenna of claim 1, further comprising a first plurality of radiating elements located forward of the first FSS and a second plurality of radiating elements located rearward of the second FSS.

14. The base station antenna of claim 13, wherein the first plurality of radiating elements operate in a first frequency band and the second plurality of radiating elements operate in a second frequency band.

15. The base station antenna of claim 14, wherein the first plurality of radiating elements comprises low-band radiating elements configured to operate in a first frequency band and the second plurality of radiating elements comprises higher-band radiating elements configured to operate in a second frequency band, the second frequency band encompassing higher frequencies than the first frequency band.

16. The base station antenna of claim 15, wherein the first FSS and the second FSS are configured to allow RF energy in the second frequency band to propagate through the first FSS and the second FSS.

17. The base station antenna of claim 1, wherein the first FSS comprises a first subset of the first array of unit cells configured to block and/or reflect RF energy in a first frequency band while allowing RF energy in a second frequency band to propagate through the first FSS, wherein the first FSS comprises a second subset of the first array of unit cells configured to block and/or reflect RF energy in the first frequency band and RF energy in a third frequency band, and wherein the third frequency band comprises frequencies between the first frequency band and the second frequency band.

18. The base station antenna of claim 17, wherein the first subset of the first array of unit cells is located at an upper portion of the base station antenna, and wherein the second subset of the first array of unit cells includes unit cells to the right of the first subset of unit cells and further includes unit cells to the left of the first subset of unit cells.

19. The base station antenna of claim 14, wherein the first plurality of radiating elements comprises high-band radiating elements operating in at least a portion of a 3.2-4.1GHz band, and wherein the second plurality of radiating elements comprises radiating elements operating in at least a portion of a lower frequency band than the high-band radiating elements.

20. The base station antenna of claim 19, wherein the first FSS and the second FSS are configured to allow RF energy in at least a portion of a 3.2-4.1GHz band to propagate through the first FSS and the second FSS.

21. The base station antenna of claim 13, wherein the second plurality of radiating elements are arranged as a multi-column array in an active antenna module.

22. The base station antenna of claim 1, wherein at least some of the first array of unit cells and/or the second array of unit cells comprise at least one transmission line (TX) segment configured to be electrically coupled to at least one inductor structure.

23. The base station antenna of claim 22, wherein a length of the at least one TX line segment is configured such that a radio frequency signal from a radiating element passing through the at least one TX line segment undergoes a 180 degree phase shift at a defined frequency.

24. The base station antenna of claim 22, wherein the length of the at least one TX line segment is about half a wavelength defining a frequency response point, optionally a second frequency response point f 2.

25. A base station antenna, comprising:

A second FSS comprising a second array of unit cells,

Wherein the first FSS is stacked in front of the second FSS in the base station antenna in the Z-direction, wherein at least some of the first array of unit cells and the second array of unit cells are configured to provide an equivalent circuit comprising at least one inductor and at least one transmission line (TX) segment configured to be electrically coupled to the at least one inductor.

26. The base station antenna of claim 25, wherein a length of the at least one TX line segment is configured such that a radio frequency signal from a radiating element passing through the at least one TX line segment undergoes a 180 degree phase shift at a defined frequency.

27. The base station antenna of claim 25, wherein the length of the at least one TX line segment is approximately half a wavelength defining a frequency response point.

28. The base station antenna of claim 25, wherein the unit cells provided by the first array and the unit cells provided by the second array are electrically coupled.

29. The base station antenna of claim 25, wherein a first unit cell in the first array of unit cells is electrically coupled to a first unit cell in the second array of unit cells, whereby the first unit cells cooperate to define an equivalent circuit to reject or block radio frequency signals of radiating elements operating in a first frequency band and to pass signals of radiating elements operating in a second frequency band.

30. A grid reflector for a base station antenna, comprising:

A Frequency Selective Surface (FSS) comprising an array of unit cells, and

Wherein at least some of the unit cells in the array of unit cells include at least one transmission line (TX) segment.

31. The mesh reflector of claim 30 wherein the length of the at least one TX line segment is approximately half a wavelength defining a frequency response point f 2.

32. The mesh reflector of claim 30 wherein the at least one TX line segment is configured such that a radio frequency signal from a radiating element passing through the at least one TX line segment undergoes a 180 phase shift at a defined frequency.

33. The grid reflector of claim 30, wherein at least some of the unit cells having the at least one transmission line segment reject radio frequency signals in a first frequency band and a second, larger frequency band corresponding to the defined frequency.

34. The mesh reflector of claim 30 wherein the at least one TX line segment includes adjacent parallel conductive lines.

35. A grid reflector for a base station antenna, comprising:

A Frequency Selective Surface (FSS) comprising a first array of unit cells having a first configuration and a second array of unit cells having a second configuration, wherein the first array comprises unit cells having a square shape and the second array comprises unit cells having a hexagonal shape, and wherein the first array extends inwardly across 30-80% of the width of the FSS and the second array is arranged in two columns on a right side portion and a left side portion of the first array.

36. The grid reflector of claim 35, wherein at least some of the array of unit cells comprise at least one transmission line (TX) segment having a length configured such that a radio frequency signal from a radiating element passing through the at least one TX line segment undergoes a 180 degree phase shift at a defined frequency.

37. The grid reflector of claim 35, wherein the FSS is configured to have a response frequency f0 of about 2.5GHz and provide a bandpass frequency range and a bandstop frequency range.

38. The mesh reflector of claim 35 wherein the at least one TX line segment has a length L that is about half a wavelength that defines a frequency response point.

39. The mesh reflector of claim 35 wherein the at least one TX line segment includes adjacent parallel conductive lines.