EP4670230A1

EP4670230A1 - SPOTLIGHT, ANTENNA, MOBILE RADIO BASE STATION AND USER DEVICE

Info

Publication number: EP4670230A1
Application number: EP23706756.6A
Authority: EP
Inventors: Sertan HASTÜRKOGLU; Markus Mohr
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2023-02-22
Filing date: 2023-02-22
Publication date: 2025-12-31
Also published as: WO2024175190A1

Abstract

A radiator (18) for an antenna (14) has a carrier (26) providing at least one surface, a radiating structure (24) and at least one transparency structure (28). The radiating structure (24) is configured for emitting and receiving electromagnetic waves in a first frequency band and the radiating structure (24) is applied to one of the at least one surface of the carrier (26). The transparency structure (28) is applied to the same surface as the radiating structure (24) or to a different one of the at least one surface of the carrier (26). The transparency structure (28) comprises a plurality of filter elements (32) for forming a frequency selective surface arranged at least in the region of the radiating structure (24). Further, an antenna (14, 16), a mobile communication base station (10), and a user device (12) are shown.

Description

Radiator, antenna, mobile communication base station as well as user device

Technical Field

The invention relates to a radiator, an antenna, a mobile communication base station as well as to a user device.

Background

In multiband antennas, radiators or arrays of radiators for at least two different frequency bands are arranged close to one another. It is known to arrange the radiators of different frequency bands one behind the other in the radiation direction of the antenna, wherein the radiators for the higher frequency band are arranged behind the radiators for the lower frequency band.

Often, the radiators of different frequency bands are interleaved, i.e. the radiators overlap with one another. As such, the electromagnetic waves of the mechanically smaller radiators for higher frequencies have to pass the mechanically larger radiators for lower frequencies, which leads to scattering and thus deterioration of signal quality.

In order to improve signal quality, attempts are known, e.g. from US 10 770 803 B2, US 10 439 285 B2 and CN 111864367 A, to increase the transparency of the mechanically larger radiators for frequencies in the second, higher frequency band by arranging conductive segments and inductive segments in alternating fashion in the radiator.

However, one problem with these concepts is that the radiating structure becomes very complex and trade-offs have to be made balancing the radiation characteristics of the radiating structure and the filter characteristics at the same time.

Summary

Thus, it is an object of the invention to provide a radiator having a transparency for a different frequency band than its own radiation frequency band which is very simple in design while providing a high signal quality.

For this purpose, in one embodiment, a radiator for an antenna is provided, comprising a carrier providing at least one surface, a radiating structure and at least one transparency structure. The radiating structure is configured for emitting and receiving electromagnetic waves in a first frequency band and the radiating structure is applied to one of the at least one surface of the carrier. The transparency structure is applied to the same surface as the radiating structure or to a different one of the at least one surface of the carrier. The transparency structure comprises a plurality of filter elements for forming a frequency selective surface arranged at least in the region of the radiating structure.

By providing a transparency structure at the same carrier as the radiating structure, the radiator itself becomes transparent for electromagnetic radiation in a frequency band different than the first frequency band. Thus, radiation of mechanically smaller radiators with a higher frequency band may pass the radiator with less scattering and less deterioration in signal quality.

For example, the filter elements are to be regarded as being in the region of the radiating structure if, in a vertical projection, the radiating structure overlaps or encircles the respective filter element. The filter elements may be suitable for creating a frequency selective surface as discussed e.g. in B. A. Munk, "Frequency Selective Surfaces: Theory and Design,” Wiley, New York, 2000.

For further improved performance, the filter elements may be arranged in an array and/or may be galvanically isolated from one another.

The array is, in an embodiment, regular.

The geometry of the filter elements may be a rectangle, a square, a tripod, a cross or a Jerusalem cross. In particular squares lead to very good performances.

In order to provide the necessary high impedance, the filter elements may have a size smaller than 1/20 of a wavelength of an average frequency of the first frequency band.

The first frequency band is the radiation frequency band of the radiator.

The size may be determined by a largest dimension of the element.

In an embodiment, the transparency structure is a frequency selective filter, providing the transparency reliably.

For example, the transparency structure is configured as a band pass filter for a second frequency band, in particular the second frequency band lying fully above the first frequency band. Using a band pass filter characteristic for the transparency structure reliably improves the signal quality.

In an aspect, the carrier is a dielectric, in particular a foil or a printed circuit board, in particular the carrier being single layered having two surfaces. This way, the radiator may be manufactured efficiently.

The carrier may be multilayered providing more than two surfaces. In this case, the inner surfaces of the carrier may also be called a layer.

For reducing manufacturing costs, the radiating structure and/or the filter elements may be formed as a metallization applied to the respective surface of the carrier.

The radiating structure may comprise at least one, in particular two dipoles, further improving the system capacity for non-line-of-sight (NLOS) connections.

For example, the radiating structure is a dual-polarized dipole, in particular with one +45-degree and one -45-degree single-polarized dipole. Each single-polarized dipole comprises two radiation dipole arms.

In an embodiment, the filter elements are provided in the entire region of the radiating structure or only in most of the region of the radiating structure. This way, the transparency may be increased further.

In an aspect, the transparency structure comprises first filter elements and second filter elements, wherein the first filter elements are different, in particular in size, from the second filter elements. This way, complex filter characteristics may be achieved. For example, the first filter elements and the second filter elements are arranged in different portions of the region of the radiating structure, further improving the filter characteristics.

In an embodiment, the first and second filters elements do not overlap.

In an embodiment, the radiator comprises two transparency structures applied to different surfaces of the carrier. This way, several band passes or other filter characteristics for more than one frequency range may be achieved.

For the above mentioned purpose, in an embodiment, further an antenna is provided. The antenna has at least one radiator as described above, in particular the antenna has a plurality of radiators forming a first array.

For example, the antenna has at least one second radiator configured for the second frequency band, in particular the antenna having a plurality of second radiators forming a second array. A compact multiband antenna is thus achieved.

Further, for the above mentioned purpose, in an embodiment, a mobile communication base station having at least one antenna as described above is provided.

Further, for the above mentioned purpose, in an embodiment, a user device for mobile communication having at least one antenna as described above is provided.

The features and advantages described with respect to the radiator also apply to the antenna, the mobile communication base station and/or the user device and vice versa.

Brief Description of the Drawings

Further features and advantages will be apparent from the following description as well as the accompanying drawings, to which reference is made. In the drawings:

Fig. 1 shows a mobile communication base station according to an embodiment of the invention with an antenna according to an embodiment of the invention and a user device according to an embodiment of the invention with an antenna according to an embodiment of the invention,

Fig. 2 shows an enlarged view of a radiator according to an embodiment of the invention of an antenna of the mobile communication base station or the user device of Figure 1,

Fig. 3 shows a cross sectional view of a radiator according to a second embodiment of the invention,

Figs. 4, 5 show a top view of the radiating structure and the transparency structure of the radiator of Figure 3, respectively,

Fig. 6 shows a top view of the radiator of Figure 3 without the carrier,

Fig. 7 shows a diagram illustrating the radar cross section over frequency of an antenna according to the invention,

Fig. 8 shows a top view of a radiator according to a third embodiment of the invention without the carrier, Fig. 9 shows a cross sectional view of a radiator according to a fourth embodiment of the invention,

Fig. 10 shows a cross sectional view of a radiator according to a fifth embodiment of the invention, and

Fig. 11 shows a top view of a radiator according to a sixth embodiment of the invention without the carrier.

Detailed Description

Figure 1 shows an embodiment of a mobile communication base station 10 and an embodiment of a user device 12.

The mobile communication base station 10 has a plurality of antennas 14 for providing speech and data connections to user devices. Mobile communication base stations 10 are also referred to as mobile communication cell sites.

The mobile communication base station 10 may be an access network node of a radio access network of a telecommunication network, or any other similar 3rd Generation Partnership Project (3GPP) access nodes or non-3GPP access points.

Moreover, as will be appreciated by those of skill in the art, an access network node is not necessarily limited to an implementation in which a radio portion and a baseband portion are supplied and integrated by a single vendor. Thus, it will be understood that network nodes may include disaggregated implementations or portions thereof.

For example, in some embodiments, the mobile communication base station 10 is an Open-RAN (ORAN) network node. An ORAN network node is a node in the telecommunication network that supports an ORAN specification (e.g., a specification published by the O-RAN Alliance, or any similar organization) and may operate alone or together with other nodes to implement one or more functionalities of any node in the telecommunication network, including one or more radio network nodes and/or core network nodes.

Examples of an ORAN network node include an open radio unit (O-RU), an open distributed unit (O- DU), and an open central unit (O-CU).

The antenna 14 of the mobile communication base station 10 is a multiband antenna to provide speech and data connections in various frequency bands.

The user device 12 has an antenna 16 and, in the illustrated embodiment, is a mobile phone. In further embodiments, the user device 12 may be a laptop computer, a customer-premises equipment (CPE), a vehicle or the like. The antenna 16 of the user device 12 is also a multiband antenna allowing a speech and/or data connection to the mobile communication base station 10 and/or to a communication satellite.

Both antennas 14, 16 have an electromagnetic radiator. In the following, a radiator 18 as shown in Figure 2 which depicts a radiator for the mobile communication base station 10 will be discussed in more detail. The antenna 14 has a plurality of radiators 18 (also called first radiators 18 for differentiation) forming a first array configured for a first frequency band. Thus, the first radiators 18 are configured to transmit and receive electromagnetic waves in the first frequency band.

Further, the antenna 14 may comprise at least one second radiator 19 (indicated with dashed lines in Figure 2), in particular a plurality of second radiators 19 forming a second array for a second frequency band.

The first radiators 18, in particular the first array, and the second radiators 19, in particular the second array, are interleaved with one another.

The first frequency band lies below the second frequency band, in particular fully.

For example, the first frequency band lies below 1.0 GHz, in particular the first frequency band may be 698 MHz to 960 MHz.

For example, the second frequency band lies above 1.0 GHz, in particular the second frequency band is 1.427 GHz to 2.69 GHz.

Figure 2 shows a radiator 18 mounted on a support 20.

In the shown embodiment, the radiator 18 is a dual polarized radiator having two dipoles 22 arranged orthogonally to one another.

The radiator 18 comprises a radiating structure 24 having four sub-structures forming a dipole arm each, a carrier 26, and a transparency structure 28 (Fig. 3).

The carrier 26 may be a substrate of a dielectric material. For example, the substrate is a printed circuit board.

It is also conceivable that the carrier 26 is provided by one or more foils carrying the radiating structure 24 and/or the transparency structure 28.

In the shown embodiment, the carrier 26 has two surfaces, namely a top surface (facing upwards in Figure 2) and a bottom surface (facing downwards in Figure 2).

It is conceivable that the carrier 26 is multilayered, e.g. a multilayered substrate. In this case, the carrier 26 comprises more than two surfaces. In multilayered substrates, inner surfaces may be referred to as layers.

The radiating structure 24 and the transparency structure 28 may be metallizations deposited on the respective surface of the carrier 26 using deposition techniques as known in the art.

The radiating structures 24 may also be manufactured using an etching process or 3D printing. The radiator 18 may be also manufactured as a molded interconnect device (MID).

Figure 3 shows a cross section through a radiator 18 of a second embodiment similar to that of Figure 2. In the embodiment of Figure 3, the radiating structure 24 is applied to the top surface of the carrier 26 and the transparency structure 28 is applied to the bottom surface of the carrier 26.

The terms "top" and "bottom" are to be understood with respect to the radiation direction R, which is substantially perpendicular to the plane spanned by the carrier 26.

Figure 4 shows the radiating structure 24 of Figure 3 in a top view, Figure 5 shows the transparency structure 28 of Figure 3 in a top view (i.e. without the carrier 26 and the radiating structure 24), and Figure 6 shows a top view of the radiating structure 24 and the transparency structure 28 in a top view without the intervening carrier 26.

In other words, Figure 6 shows a vertical projection of the radiating structure 24 on the transparency structure 28.

As best seen in Figure 4, the radiating structure 24 comprises four square-shaped conductors 30 arranged in a 2 x 2 grid. Each one of the conductors 30 forms one of the dipole arms. The conductors 30 are also illustrated in Figures 2 and 3.

The radiating structure 24, i.e. the conductors 30 are designed to emit and receive electromagnetic waves in the first frequency band.

In the illustrated embodiment, the conductors 30 are arranged in a closed loop, thus encircling an area within. The conductors 30 may also be arranged in an open-ended loop of at least 300°.

The region of the radiating structure 24 includes the area occupied by the conductors 30 itself, the area encircled by the conductors 30 and the area between neighboring conductors 30.

The transparency structure 28 comprises a plurality of filter elements 32.

In the shown embodiment, all filter elements 32 are the same and have a geometry of a tripod, i.e. they are three legged (see Fig. 5).

The geometry may as well be a rectangular, a square, a cross or a Jerusalem cross or any other shape suitable for a frequency selective surface. Geometries suitable for frequency selective surfaces may be found in B. A. Munk, "Frequency Selective Surfaces: Theory and Design,” Wiley, New York, 2000, wherein the description of the geometries is incorporated by reference.

The size of the filter elements 32, i.e. the extent of the largest dimension, is smaller than one 1/20 of the wavelengths of an average frequency of the first frequency band.

The filter elements 32 are arranged in a regular array close to one another but without physical contact. Thus, the filter elements 32 are galvanically isolated from one another.

This way, the array of filter element 32 and thus the transparency structure 28 forms a frequency selective filter.

The frequency selectivity of the transparency structure 28 is such that a bandpass is created in the second frequency band. The second frequency band lies in a frequency band fully above the first frequency band. The frequency selectivity of the transparency structure 28 causes a lower induced current from the second radiator 19 of the second frequency band in the first radiator 18 than without the transparency structure 28. The lower current on the first radiator 18 of the first frequency band provides less scattering of electromagnetic waves, therefore the RF parameters such as S-parameters and far field characteristics are less disturbed.

Figure 7 shows a diagram illustrating the radar cross section over frequency of the antenna 14 according to the invention (three lower lines marked with squares and triangles) and for comparison a radar cross section over frequency of the same antenna but without the transparency structure 28 (upper line marked with circles).

As best seen in Figure 6, in the illustrated embodiment the array of filter elements 32 extends over the entire surface of the carrier 26 and over the entire region of the radiating structure 24.

Due to the transparency structure 28, electromagnetic waves emitted from the second radiators 19 may pass the first radiator 18 only with little scattering and losses. This drastically improves the signal quality of the second radiators 19 and thus the performance of the antenna 14 in the second frequency band.

At the same time, the radiating structure 24 can be optimized to the first frequency band and carried out in a very simple fashion.

Figures 8 to 11 show further embodiments of a radiator 18 according to the invention, corresponding substantially to the embodiments discussed above. Thus, in the following, only the differences are discussed and the same and functionally the same components are labeled with the same reference signs.

Figure 8 shows a radiator 18 according to a third embodiment in a view similar to that of Figure 6.

In this embodiment, the transparency structure 28 comprises filter elements 32 being Jerusalem crosses.

Figure 9 shows a fourth embodiment of a radiator 18 according to the invention in a sectional view similar to that of Figure 3.

As can be seen, the transparency structure 28, i.e. the filter elements 32 are also arranged on the top surface of the carrier 26. Thus, both the transparency structure 28 and the radiating structure 24 are arranged on the same surface of the carrier 26.

The filter elements 32 of the transparency structure 28 and the conductors 30 of the radiating structure 24 are galvanically isolated from one another.

In particular, the filter elements 32 are encircled by one of the conductors 30 or are arranged between adjacent conductors 30.

Figure 10 shows a fifth embodiment of a radiator 18 according to the invention in a sectional view similar to that of Figure 3.

In this fifth embodiment, the carrier 26 is a multilayered carrier, having three surfaces. The inner surface is located between the two layers of the carrier 26.

In the fifth embodiment, the radiating structure 24 is also located at the top surface and two transparency structures 28 are provided.

The first transparency structure 28 is located on the inner surface, i.e. the bottom surface of the upper layer of the carrier 26.

The second transparency structure 28 is located at the bottom surface of the carrier 26.

The transparency structures 28 may be different from one another so that they create a bandpass or any other characteristics for different frequency bands. For example, the second transparency structure 28 creates a transparency (bandpass) of the radiator 18 in a third frequency band, which might correspond to a frequency band of third radiators (not shown) of the antenna 14.

Figure 11 shows a sixth embodiment of a radiator 18 according to the invention in a view similar to that of Figure 6.

In this sixth embodiment, the transparency structure 28 comprises two different kinds of filter elements 32, namely first filter elements 34 and second filter elements 36.

The first filter elements 34 and the second filter elements 36 are different from one another, in particular they differ in size.

In the sixth embodiment shown in Figure 11, both the first filter elements 34 and the second filter elements 36 have the geometry of a square, wherein the size of the squared geometry is different.

In particular, the size of the second filter elements 36 is larger than the size of the first filter elements 34.

Further, the first and second filter elements 34, 36 cover different portions of the region of the radiating structure 24.

The first filter elements 34 are arranged around the central portion of the region of the radiating structure 24.

The second filter elements 36 are arranged in four separate groups, wherein within each group the second filter elements 36 are arranged in a regular grid.

The four groups are located at the four corners of the radiating structure 24, i.e. each group at the outer corner of one of the conductors 30.

Neither the first filter elements 34 nor the second filter elements 36 cover the entire region of the radiating structure 24.

The portions of the region covered by the first filter elements 34 and the portions covered by the second filter elements 36 are distinct from one another so that the first filter elements 34 and the second filter elements 36 do not overlap. In fact, the portions are spaced apart from one another. The transparency structure 28 thus does not cover the entire region of the radiating structure 24, but the majority, i.e. more than 50% of the region of the radiating structure 24.

With two different kinds of filter elements 34, 36, the functionality of the transparency structure 28 is more versatile.

The shown embodiments are only exemplary. The features of the embodiments may be combined freely. In the foregoing detailed description, a radiator for a mobile communication base station was discussed. A radiator for an antenna of a user device may be structurally different from said radiator for a mobile communication base station, e.g. the radiator may be a monopole instead of a dipole. Still, a transparency structure as described in detail above may be included in such a radiator for an antenna of a user device.

Claims

1. Radiator for an antenna (14), comprising a carrier (26) providing at least one surface, a radiating structure (24) and at least one transparency structure (28), wherein the radiating structure (24) is configured for emitting and receiving electromagnetic waves in a first frequency band and the radiating structure (24) is applied to one of the at least one surface of the carrier (26), wherein the transparency structure (28) is applied to the same surface as the radiating structure (24) or to a different one of the at least one surface of the carrier (26), and wherein the transparency structure (28) comprises a plurality of filter elements (32) for forming a frequency selective surface arranged at least in the region of the radiating structure (24).

2. Radiator according to claim 1, characterized in that the filter elements (32) are arranged in an array and/or are galvanically isolated from one another.

3. Radiator according to claim 1 or 2, characterized in that the geometry of the filter elements

(32) is a rectangle, a square, a tripod, a cross or a Jerusalem cross.

4. Radiator according to any of the preceding claims, characterized in that the filter elements

(32) have a size smaller than 1/20 of a wavelength of an average frequency of the first frequency band.

5. Radiator according to any of the preceding claims, characterized in that the transparency structure (28) is a frequency selective filter.

6. Radiator according to claim 1, characterized in that the transparency structure (28) is configured as a band pass filter for a second frequency band, in particular the second frequency band lying fully above the first frequency band.

7. Radiator according to any of the preceding claims, characterized in that the carrier (26) is a dielectric, in particular a foil or a printed circuit board, in particular the carrier (26) being single layered having two surfaces.

8. Radiator according to any of the preceding claims, characterized in that the radiating structure (24) and/or the filter elements (32) are formed as a metallization applied to the respective surface of the carrier (26).

9. Radiator according to any of the preceding claims, characterized in that the radiating structure (24) comprises at least one, in particular two dipoles (22).

10. Radiator according to any of the preceding claims, characterized in that the filter elements (32) are provided in the entire region of the radiating structure (24) or only in most of the region of the radiating structure (24).

11. Radiator according to any of the preceding claims, characterized in that the transparency structure (28) comprises first filter elements (34) and second filter elements (36), wherein the first filter elements (34) are different, in particular in size, from the second filter elements (36).

12. Radiator according to claim 11, characterized in that the first filter elements (34) and the second filter elements (36) are arranged in different portions of the region of the radiating structure (24).

13. Radiator according to any of the preceding claims, characterized in that the radiator (18) comprises two transparency structures (28) applied to different surfaces of the carrier (26).

14. Antenna having at least one radiator (18) according to any one of the preceding claims, in particular the antenna (14, 16) having a plurality of radiators (18) forming a first array.

15. Antenna according to claim 14, wherein the antenna (14, 16) has at least one second radiator (19) designed for the second frequency band, in particular the antenna (14, 16) having a plurality of second radiators (19) forming a second array.

16. Mobile communication base station having at least one antenna (14) according to claim 14 or 15.

17. User device for mobile communication having at least one antenna (16) according to claim 14 or 15.