CN1736000A - Low-cost antenna array - Google Patents

Abstract

This invention describes a low-cost antenna array and a method for manufacturing the array, which may be planar, structurally flexible, or curved. The antenna array includes multiple electrically charged metallic antenna and radiator elements formed on a foam core layer bonded to a metallic substrate. The radiator elements are preferably formed on a thin dielectric layer bonded to the foam core layer. The antenna array may include multiple additional dielectric layers, each on which multiple passive radiator elements are formed, mounted on top of the charged radiator elements. Manufacturing the antenna array preferably involves bonding the layers together. When forming the charged radiator elements, the foam core layer is preferably etched before bonding it to the substrate. Then, the additional dielectric layers and passive radiator elements are bonded to the charged radiator elements already formed on the substrate.

Description

low cost antenna array

technical field

The present invention relates to antenna arrays, and more particularly to low cost antenna arrays having substantially planar and curved surfaces, for use in telecommunications, and methods of making the same.

Background technique

Antenna arrays are manufactured in various forms and have many different applications within the communications field. A specific application is antenna arrays with high volume and emphasis on low cost, which are used in base stations of mobile communication systems, such as the cellular transmission system in the United States operating at about 800 MHz and the personal communication service (PCS) operating at about 1900 MHz system base stations, and in other wireless and mobile communication applications worldwide.

Base station antenna arrays come in a wide variety of configurations that differ significantly in size, cost, and reliability. The usual basic antenna array typically includes: two or more individual radiators; a transmission network that distributes the RF power from the antenna interface between the radiators; a mechanical structure that ensures that all elements form a combined body; and a radome. One basic type of base station antenna array consists of the well known array of cylindrical dipoles. Such antenna arrays typically have a large number of components, are structurally expensive to manufacture, have large physical dimensions, and are relatively heavy. Another basic type of base station antenna array uses sheet metal dipole radiators consisting of thin metal sheets supported by discrete dielectric spacers to form a microstrip power distribution network. The individual metal parts are usually stamped from thin sheets of aluminum and then assembled using intensive labor. Another conventional base station antenna array uses a printed circuit board (PCB) to form the power distribution circuit, using coaxial cables to connect metal dipoles or wiring radiators.

Yet another type of conventional base station antenna array uses PCBs for the power distribution network and separate PCBs for the dipole radiators. For base station antennas with high gain values and more than 8 radiators, it is usually necessary to use high-performance polytetrafluoroethylene (PTFE)-based PCB materials to form power distribution networks to keep network losses low and avoid signal attenuation. PCB materials based on high-performance PTFE are much more expensive than other types of PCB materials. The application of base station antennas consisting of PCBs as power distribution network and radiators gives advantages over similar antennas composed of metal foils in terms of production tooling costs, ease of processing, assembly and favorable realization of greater circuit complexity .

Various configurations of planar antenna arrays have been proposed to reduce manufacturing costs, reduce physical size, and reduce overall antenna array weight. These antenna arrays come in a variety of structures in composition, utilize a variety of sandwich-type arrangements, and utilize a variety of materials for antenna radiators and circuits. Usually, the screen printing method or physical cutting of the metal layer is used to form a planar antenna array, such as forming radiator wiring in the metal layer by punching out the radiator wiring or cutting the metal layer, and forming by etching the metal layer. desired pattern. These types of antennas consist of one or more circuits and radiators formed on a very thin layer or sheet of metal, which are then supported or mounted on a generally stronger dielectric substrate of various types, such as plastic, foam, Styrofoam ^TM , PVC resin, fiberglass, polypropylene, polyester, acrylic, or polyethylene as substrates. Although these conventional array structures improve certain characteristics of antenna arrays, such as small number of parts and light weight, improvements are still needed in terms of electrical performance, manufacturing process cost and overall mechanical structure.

Therefore, there is a need for an antenna array, for example for base station applications, which can be manufactured at reduced cost. It is also desirable to maintain acceptable electrical performance of the antenna array while achieving a reduction in the cost of the required array. Further, it is hoped to form a flexible antenna array, which can be made into a curved structure and applied to certain occasions.

Contents of the invention

The present invention is directed to low cost antenna arrays and methods of making such arrays for use in communications applications, such as for use as base station antennas. The antenna array according to the present invention can be designed in a planar form or have a flexible structure, or a curved surface array structure desired in some applications.

Antenna arrays according to embodiments of the present invention are composed of multiple layers, which are preferably bonded to each other. The antenna array includes a plurality of metal radiator units formed on two or more dielectric layers, and the dielectric layers are sequentially bonded to the metal base layer. The thickness of the dielectric layer is chosen to provide the required separation for the operational application of the radiator unit. The radiator units are preferably formed on a flexible dielectric carrier layer which may be bonded to a dielectric foam core layer which may be flexible or may be molded or cut into planar shapes or non-planar shaped. The array may include one or more dielectric layers on which a number of passive radiator elements may be formed, wherein the dielectric layer is preferably bonded on top of the metallic radiator elements. The dielectric and substrate layers are enclosed within the structure comprising the radome, providing protection from the external environment and facilitating mounting of the antenna assembly to other structures in a safe and robust condition.

In the array manufacturing method according to the embodiment of the present invention, the various layers are bonded to each other. For the formation of the radiator unit, it is desirable to etch the metal layer prior to bonding the foam core dielectric layer to the substrate layer. Then, the dielectric layer with the passive radiator elements is glued onto the already formed radiator elements. The base layer may be partially or entirely curved as required.

In the design of the low-cost antenna array according to the embodiment of the present invention, various low-cost components suitable for printed circuit board manufacturing technology are used, and they can be assembled together in a short time, and only a small amount of adjustment or no adjustment is required after assembly The desired performance can be obtained.

Therefore, the present invention provides an antenna array with a multilayer structure, which includes: a metal layer on which a plurality of powered antenna radiator elements and feed elements are formed; a first thin carrier medium layer on which the metal layer is formed. On the first thin carrier medium layer; a foam core layer having a top surface and a bottom surface, wherein the first thin carrier medium layer is formed on the top surface of the foam core layer, and the adhesive layer is formed on the bottom surface of the foam core layer, Wherein, the adhesive layer is adhered to the metal base layer.

Other features and advantages of the present invention are readily understood from the following detailed description when read in conjunction with the accompanying drawings.

Description of drawings

Figure 1 illustrates an antenna array according to an embodiment of the invention applied within a base station environment;

Figure 2 is an exploded perspective view illustrating an antenna array according to an embodiment of the present invention;

Figure 3 is an exploded perspective view showing the antenna array of Figure 2 with radome elements forming a complete antenna structure;

Figure 4 is an enlarged exploded perspective view partially illustrating the antenna array of Figure 2;

Figure 5 is an enlarged exploded end view showing the antenna array of Figure 2;

Figure 6 is a perspective view illustrating the antenna array of Figure 2 with a radome forming part of the complete antenna structure;

Figure 7 is a top view of the partially complete antenna structure of Figure 6;

Figure 8 is an exploded perspective view showing an antenna array according to another embodiment of the present invention;

Figure 9 is an exploded perspective view showing the antenna array embodiment of Figure 8 with radome elements forming a complete antenna structure;

Figure 10 is an exploded perspective view partially illustrating the antenna array embodiment of Figure 8;

Figure 11 is an enlarged exploded side view showing the antenna array embodiment of Figure 8;

Figure 12 is a partial perspective view showing the antenna array embodiment of Figure 8 with radome elements forming part of the complete antenna structure;

Figure 13 is a top view of the partially complete antenna structure of Figure 12;

14A, 14B and 14C are respectively a side view, a bottom view and a top view of a complete antenna array structure installed in a radome unit;

Figure 15 is a cross-sectional view of the complete antenna array and radome structure taken along line 15-15 in Figure 14A;

Figure 16 is a perspective view of the complete antenna array structure on Figure 15;

17 is a perspective view of an embodiment of a curved antenna array of the present invention;

Figure 18 is a partial perspective view of the enlarged structure of the antenna array in Figure 17;

19A and 19B are perspective and top views, respectively, of another curved antenna array embodiment of the present invention;

Figure 20 is a schematic diagram illustrating the application of the curved antenna array of the present invention in a base station environment;

Figure 21 shows the process steps of manufacturing an embodiment of an antenna array of the present invention;

Figure 22 shows the process steps of manufacturing another antenna array embodiment of the present invention;

Figure 23 is a partial perspective view illustrating an antenna array radome embodiment of the present invention capable of supporting a complete antenna structure;

Figure 24 is a side or end view of the radome of Figure 23 with the complete antenna structure mounted thereon; and

Figure 25 is a partial perspective view illustrating the radome unit of Figure 23 with the antenna structure installed therein.

Detailed ways

Referring now to FIG. 1, a base station or cell site 10 may include at least one and usually a plurality of antenna arrays 12 of the present invention, the implementation of which is disclosed in detail in FIGS. 2-16. The same reference numerals indicated in these figures refer to the same or similar parts in each figure. Base station antenna array 12 is typically contained within a substantially airtight radome (shown in FIGS. 14-16 ), which is then mounted to base station mast 14 in a conventional manner. As used here, an antenna array is a combination of antenna elements of a size, spacing, and radiation sequence such that the combined electric field of the individual radiator elements produces a maximum strength in a particular direction, while the electric field is extremely strong in other directions. Small. When describing such a combination, the term antenna array may be used interchangeably with array antenna.

Each of the base station antenna arrays 12 provides coverage to a cell of a mobile or fixed communication system (not shown), such as a cellular transmission system operating at about 800 MHz for the United States and Coverage is provided by Personal Communications Service (PCS) systems operating at about 1900 MHz, or for other antenna communications with fixed or mobile subscriber systems. The base station antenna array of the present invention is shown as a planar structure in the antenna array 12 and as a curved structure in the curved antenna array 18 (the examples of the curved structure are disclosed in detail in FIGS. 17 to 20 ). The curved antenna array 18 can be installed on the second base station tower mast 14', which can increase the communication coverage of the base station 10 to the top of the coverage area 16, such as reaching the top of a hill or on an aircraft 19.

The first embodiment of the antenna array of the present invention is shown in FIG. 2 in an exploded view, and each unit in the figure is not drawn to scale. Antenna array embodiment 20 is a dual polarized antenna comprising two orthogonal linear polarizations, shown here as 16 individual radiators. Those skilled in the art know that the present invention is not limited to dual-polarized antennas, but can also be applied to antennas with a single polarization characteristic, and can also be applied to the number of radiators different from the illustrated embodiment , the number of radiators in the array can be less or more. Included within the array 20 is a PCB stack or interlayer 22 comprising a plurality of radiator elements or wiring 24 formed on a metal layer 60 (shown in FIG. 5 ) along the length of the stack 22 and arranged in a conventional manner. The radiator elements 24 are connected with feed circuits 26 as required. Preferably, the metal layer 60 is first attached or bonded to the relatively thin carrier dielectric layer 27, such as by means of an adhesive layer 62 (shown in FIG. A plurality of radiator elements or wires 24 are formed along the length thereof, and the radiator elements 24 are connected with feed circuits 26 as required. It should be understood that the term bonding may include conventional techniques for bonding, including but not limited to the application of adhesives or fasteners for joining.

The PCB stack 22 is then bonded to the relatively thick foam core dielectric layer 28 by means of an adhesive layer 30 . The remainder of the antenna array 20 desirably includes an adhesive and release layer 32 which is first bonded to the bottom side of the foam core dielectric layer 28 to complete a stack or sandwich assembly 34 when the layers are bonded together. A multiplicity of radiator elements or wiring 24 with the required feed circuits 26 can also be formed on the assembly at this point, for example by means of a customary chemical etching process. After the radiator elements 24 have been formed as required for the feed circuit 26, the stack 34 is trimmed in a conventional manner. Then, a release portion of layer 32 (such as a polyester material or similar release layer, not shown) is removed, and stack 34 is bonded to base layer or conductive support 35 by means of the remaining adhesive.

Each of the stack 22 , the dielectric layer 28 and the conductive support 35 includes a pair of central aperture sets 36 which intermesh for use in making radio frequency signal connections to the feed circuit 26 on the PCB stack 22 . Formed along the edges of the stack 22, dielectric layer 28 and conductive support 35 are additional sets of engaging apertures 38 for mounting a mounting bracket 48 to the conductive support 35 (as shown in FIG. 3). Bolts or screws or similar devices (not shown) are received by set of apertures 38 in conductive mount 35 and tolerance clearance for bolt heads is provided by set of apertures 38 in stack 22 and dielectric layer 28 .

The stack 34 and conductive support 35 are mounted together to form part of an antenna structure 40, these components being shown in FIG. An enclosure for the antenna array 20 is formed on the antenna structure 40 to protect the antenna from environmental conditions, such as rain, hail, snow, dust and wind. Although antenna array 20 is typically mounted in an exposed location on a base station, in other applications antenna array 20 may be mounted with or without other types of protection or enclosures. Included in the antenna structure 40 is a radome cover member 42 which may be mounted to the bottom conductive bracket 35 . Both ends of the radome cover 42 are enclosed by a pair of end caps 44, which are secured to the base layer 35 or the radome cover 42 by fasteners such as screws (not shown) to form a fully enclosed antenna structure 40.

The radome cover 42 can be manufactured by molding from a suitable outdoor grade plastic material, ensuring proper radio frequency performance with respect to losses, and having a suitable dielectric constant. The plastic material should also have suitable dimensional stability and not become brittle at low temperatures. The radome material is preferably an outdoor grade polyvinyl chloride (PVC), which contains an anti-ultraviolet (UV) stabilizer material to maintain durability in an outdoor environment. Using PVC material is a good choice, it has been proved that it can be used as the radome of the base station.

The base layer 35 contains a pair of central aperture sets 36 which are engageable with aperture sets 36 in other layers. Aperture set 36 serves a pair of RF connections 46 for transmitting RF power to feed circuit 26 on PCB stack 22 . The radio frequency connection 46 forms an interface port or port connection for the antenna structure 40 . Since the only metal-to-metal contact in the antenna structure 20 or 40 within the direct RF signal path is the solder joint connection at the RF connector 46, the resulting antenna structure 20 or 40 provides good passive intermodulation (PIM) performance. PIM is typically less than -150 when tested with two carrier tones at 20W per tone.

The antenna structure 40 desirably further includes a pair of mounting brackets 48 securable to the base layer 35 through the aperture set 38 as previously described by means of fasteners such as bolts or screws (not shown). The bracket 48 should be used to mount the antenna 12 at any desired location, such as on the cell mast 14 .

Stack 34 and base layer 35 are shown in an enlarged partial perspective view in FIG. 4 . It shows more clearly the PCB stack 22 with the radiator unit 24 and the feed circuit 26 . Additionally, at least one of the dielectric layer 28 and the base layer 35 each includes a pair of apertures 50 over which end caps 44 are mounted. Aperture pair 50 may also be used for alignment of stack 22 , layers 22 , 28 , 30 and 32 (each of which contains aperture pair 50 , if desired) when stack 34 is manufactured and mounted to conductive support 35 . Generally, apertures can be formed in each layer of the stack to ensure tolerance clearance around the fastener or raised features that would otherwise have localized protrusions in different stacks.

Stack 34 and conductive support 35 are again shown in an enlarged end view in FIG. 5 . Likewise, elements are not shown to scale. In addition, relatively thin carrier dielectric layer 27 is spaced apart from metal layer 60 on which has been or will be patterned to form radiator 24 and feed circuit 26 . The metal layer 60 is adhered to the carrier medium layer 27 by means of the adhesive layer 62 to form the stack 22 . The conductive bracket 35 further preferably includes a pair of opposed longitudinal edge slots for sliding the radome cover 42 in before the end cap 44 is mounted on the conductive bracket 35 .

While the specific materials and thicknesses of the layers are not critical, some typical dimensions and materials are listed below. In a preferred embodiment, metal layer 60 is a thin copper foil that is etched to form cells 24 and 26 . Copper foil 60 is desirably electrodeposited (ED) type copper foil, for the copper foil in contact with the surface of the adhesive layer 62 on the carrier medium layer 27, chemical treatment can be carried out, this treatment is usually called reverse treatment copper foil. foil. Metal layer 60 weighs 1 ounce per square foot of area, corresponding to a thickness of approximately 0.0014 inches. Other copper foils can also be used, including generally more expensive rolled copper foils and ED copper foils which have a reduced surface profile on the bonding side. Copper foil is available in various weights such as 0.5 or 2 ounces per square foot may be used. From the perspective of the cost and signal current capacity of the base station antenna, 1 oz copper foil is desirable. The carrier dielectric layer 27 can be a low loss polyester film with a thickness of approximately 0.003 to 0.005 inches, and can be as thick as 0.010 inches. The metal layer 60 and the relatively thin carrier medium layer 27 can be glued together with a relatively thin adhesive layer 62 . Adhesive layer 62 can be applied between metal layer 60 and carrier medium layer 27 in conjunction with a wet coating process, solidifies to form a manageable sheet, and is subsequently processed into an integral assembly or stack 22 . The resulting sheet assembly or stack 22 is generally flexible and can be formed into a curved shape in at least one plane.

The foam core layer 28 is preferably a closed cell foam, thereby substantially preventing moisture from being drawn into the antenna environment, and allowing the foam core layer 28 to withstand wet printed circuit board processes, absorbing relatively small amounts of fluid. The foam core layer 28 may be an expanded polyolefin plastic material having a typical density of 2, 4, 6, 9 or 12 pounds per cubic foot. One such material is expanded polyethylene, which is desirably capable of forming cross-links during manufacture using typical radiation processes, enhancing the material properties. In other molding processes, thermally activated chemical crosslinking agents can be used. A crosslinked bonded closed cell expanded polyethylene foam using the radiation process is known as VultraCell ^(TM ) manufactured by Vulcan Corporation, Tennessee Corporation and a wholly owned subsidiary of Vulcan International Corporation and Delaware Corporation. A second type of cross-linked closed cell expanded polyethylene foam is known as Volara ^(TM) manufactured by Vlotek, a division of Sekisui America Corporation. Valtek manufactures various grades of other crosslinked closed cell polyolefin foams suitable for this application. rolls of polyolefin foam are flexible and can be formed into shapes for other purposes by bonding, and antennas can be fabricated to exhibit curvature in one or more planes using the components described here and conventional processing and assembly techniques shape.

The dielectric constant of the foam core layer 28 depends on the density and dielectric constant of the expanded material used to form the foam core layer 28 . Rigid, low-density foams such as expanded polystyrene (EPS), manufactured by molding, typically have a density of 1.25 to 2.5 pounds per cubic foot. These low-density foams have a dielectric constant of 1.02 to 1.04, which is close to that of air. Instead of expanded polystyrene foam, extruded polystyrene foam is preferable because the small void channels that occur when foam particles are used to construct expanded foam are reduced and moisture uptake is reduced. Nevertheless, the moisture uptake of EPS is low enough for some applications. Extruded cross-linked polyethylene foam with a density of 6 pounds per cubic foot has a typical dielectric constant of 2.3. Other crosslinked expanded polyolefin foams have a dielectric constant value of 1.35. A foam core layer 28 useful in the present invention has a thickness of approximately 0.090 inches. Plastic materials have a low density and generally have a low dissipation factor at small values of the dielectric constant.

The rigid foam material that can be applied to the foam core medium layer 28 is Rohacell ^™ manufactured by EMKAY Plastics Co., Ltd., Norwich, UK. Rohacell ^™ is a polymethacrylate (PMI) rigid foam, free of CFCs, bromine and halogens, which is said to be 100% density cells and isotropic. Rohacell ^TM foam has excellent mechanical properties, high dimensional stability at high temperature, solvent resistance, and particularly low thermal conductivity. Their strength values and modulus of elasticity and shear modulus have hitherto not been surpassed by any other foamed plastics of the same gross density. The Rohacell ^(TM) foam is available in various densities including 2, 3.25, 4.68 and 6.87 pounds per cubic foot. At the same density, the dielectric constant of Rohacell ^™ foam is generally lower than that of flexible polyolefin family foams. For example, 4.68 pounds per cubic inch of Rohacell ^™ foam has a dielectric constant of approximately 1.08 at 2 GHz. Rohacell( ^TM) foam can be made thermoelastic. Therefore, it can be formed at a temperature of 170°C-190°C. The required deformation temperature depends on the degree of forming and density. In some cases curved foam shapes can be obtained mechanically or deformed under heat.

The conductive support 35 can be formed of aluminum with a thickness of about 0.125 inches. Those skilled in the art know that the conductive support or base layer 35 in the illustrated embodiment is also a key structural element, and the relative thickness shown is Already has the required hardness and strength. Other embodiments are possible, including relying on the radome cover 42 as the key structural element, while the base layer 35 may be a relatively thin aluminum or other suitable metal layer of conductive material, on the order of 0.003-0.010 inches thick.

One embodiment of FIG. 5 comprising a stack 22 of metal layer 60, adhesive layer 62, and relatively thin carrier dielectric layer 27 is available from Arlon Engineering Foil and Coating Company, East Providence, Rhode Island, USA available elsewhere, see its copper-clad polyester sheet (CPL) product description. Adhesive layer 62 in Arlon CPL products is a proprietary Arlon thermoforming urethane adhesive system. The metallized conductive stack 22 is available from a number of suppliers in the flexible circuit industry, and the relatively thin carrier dielectric layer 27 is a product of polyimide material, known as DuPont's Kapton ^™ film. Arlon CPL products are preferable to polyimide film based sheets due to their lower dielectric constant and much lower water absorption.

Adhesive layers 30 and 62 may be a polypropylene pressure sensitive transfer adhesive, such as a type made by 3M Company in St. Paul, Minnesota under the trade designation VHB( ^TM) , having a thickness on the order of 0.002-0.005 inches. Other polypropylene adhesive systems can also be used, including wet application systems. Although polypropylene adhesive systems are preferred, the present invention is not limited to use with polypropylene adhesive systems only. For the adhesive layer 32 , it is advisable to apply a pressure sensitive adhesive (PSA) to facilitate assembly of the stack 34 to the base layer 35 .

The relatively thin carrier medium 27 is not limited to polyester material, any suitable low-cost plastic material with relatively low moisture and radio frequency energy absorption can be used, and they are substantially between the foam core layer 28 and the copper foil 60. Acts as a permeation-resistant polymeric membrane. The plastic material should also provide a smooth surface for printing and etching applications and further act as a barrier layer preventing penetration of the surface of the foam core layer 28 during chemical processing typical in the PCB industry. The use of a relatively thin carrier dielectric layer 27 is a key factor in the construction of low-cost antennas, which facilitates the use of standard PCB technology in the fabrication of the conductive pattern to allow the required feed circuit 26 to be connected to the radiator element 24 , and are readily bonded to the foam core layer 28 using conventional polypropylene adhesive systems. The foam core layer 28 can be flexible, or can be molded or cut into the desired planar or non-planar configuration.

6 and 7 show two views of a partial assembly of an antenna structure 40, including the assembled stacks 22 and 34 and the layers 28, 30 and 32 bonded to each other, mounted on a base layer 35 without adding The radome covers 42 .

A second antenna array embodiment 70 of the present invention comprising substantially the same stack 34 as the first antenna array embodiment 20 is shown in exploded view in FIG. 8 . In addition to the layers of stack 34, antenna array 70 described above includes a stack 71 similar to stack 22, on which passive radiator elements or wiring sets 72 are preferably formed on or adhered to a thin film by means of an adhesive layer. on the carrier medium layer 74 (shown in FIG. 11 ). The passive radiator element or wiring set 72 can be energized by the radiator element or wiring set 24, which can increase the size of the antenna array 20 compared to a similar antenna array design without the passive radiator element or wiring set 72. working bandwidth. Thin carrier medium layer 74 may be identical to thin carrier medium layer 27 . The radiator unit 72 is passively coupled to the corresponding radiator unit 24 . The radiator unit 72 does not include any feeder circuit, but the radiator unit 72 is spaced a predetermined distance from the stack 22 by means of a further dielectric layer 76 having a thickness equal to the required distance between the associated radiator units 24 and 72. The predetermined distance of passive coupling. Dielectric layer 76 is connected or bonded to stack 71 by adhesive layer 78 . The radiator unit 72 can be directly connected to the dielectric layer 76 without the dielectric layer 74 and the adhesive layer 78 . Dielectric layer 76 may be formed from conventional expanded polystyrene material, molded or cut to desired dimensions. A preferred embodiment of the media layer is a monolithic closed cell foam structure having a relatively low density value and a substantially uniform thickness value. The dielectric layer 76 is then bonded to the top of the stack 22 by means of an adhesive layer 80 . The stack 71 comprising the additional carrier dielectric layer 74 with the radiator unit 72 thereon and the dielectric layer 76 together with the stack 34 constitutes a further multilayer assembly or stack 82 for mounting as previously described to a conductive Support 35 on.

The stack 82 on the conductive support 35 is in turn mounted into the antenna structure 40 as shown in FIG. 9 , which contains the same components as those previously shown for FIG. 3 . Apart from the addition of two layers 74 and 76, the two antenna structures 20 and 70 may be identical.

The enlarged partial perspective view in FIG. 10 illustrates a stack or sandwich structure 82 . Together with the stack 71 and the medium 76 , the conductive stack 22 with the radiator unit 24 and the feed circuit 26 is shown more clearly. Foam core layer 28 and base layer 35 each further include a pair of apertures 50 to which end caps 44 are mounted. The pair of apertures 50 can in turn be used to align the layers with each other during fabrication of the sandwich structure 82 and its mounting on the conductive support 35 .

The stack 82 with the conductive support 35 is again shown in an enlarged end view in FIG. 11 . Likewise, the layers are not shown to scale. In addition, dielectric layer 74 is shown spaced apart from passive radiator element set 72, which has been or will be patterned (not shown) from a metal layer. The metal layer or formed radiator element group 72 is bonded to the carrier medium layer 74 by means of an adhesive layer 73 . In a preferred embodiment, the conductive layer 72 may be a thin copper foil similar to the metal layer 60 . The carrier medium layer 74 is similar to the carrier medium layer 27, and can also be a relatively thin low-loss polyester material, with a thickness of about 0.003-0.005 inches. Dielectric layer 76 may be closed cell polystyrene, low loss, low dielectric constant, approximately 0.375 inches thick. Adhesive layers 73, 78 and 80 are likewise conventional pressure sensitive adhesives and are approximately 0.002-0.005 inches thick. In other embodiments, the conductive layer 72 may be a laser cut or stamp cut sheet of aluminum, brass or copper with a thickness on the order of 0.05 inches. The individual radiator wires 72 may then be individual sheet pieces bonded to the carrier dielectric layer 74 where they can be bonded directly to the dielectric layer 76 . When formed as individual wires, radiator wire group 72 may be formed in any suitable thickness dimension as desired for a particular antenna application.

Figures 12 and 13 show two views of a portion of the assembled antenna structure 70, comprising the assembled stack 82 and the interconnected layers 22, 28, 74 and 76, mounted on the base layer 35 but not covered by the radome 42.

14A , 14B, 14C, 15 and 16 show various views of the assembled stack 82 within the radome forming the antenna structures 40 in the antenna array 70 .

The antenna array embodiments shown in Figures 17 to 20 are non-planar, with portions of the antenna array being non-planar. In the implementation of these designs, it is desirable to use a material for the foam core layer 28 that is flexible or that can be thermoformed from a planar sheet.

Figure 17 shows a perspective view of a curved antenna array embodiment 90 of the present invention. Dielectric layers 27 and 28 may be formed from a flexible material, such as compressible and conformable foam, or may be molded or cut as previously described. As an example of an antenna array, antenna array 90 is formed on a cylindrical substrate or base layer 92 and includes two stacks 34 that form a pair of antennas 20 having a plurality of radiator elements 24 . By forming the antenna 20 on a cylindrical or curved substrate 92, the antenna 20 can give substantially 360° coverage. A radome structure similar to that of antenna structure 40 (not shown) may be mounted on antenna array 90 to form an antenna structure that is aesthetically pleasing with reduced size and weight. Antenna array 90 may then be mounted as desired, such as on or above cell tower mast 14 (not shown).

FIG. 18 is an enlarged partial perspective view of antenna array 90 including a portion of one of antennas 20 of FIG. 17 . The antenna array 90 may also be used without a radome, but may include a protective coating or other type of covering if desired for a particular application.

In the embodiment shown in Figures 17 and 18, the bending direction of the antenna 20 around the cylinder 92 is in the direction transverse to the plane of the antenna array 90 along the length of the cylinder. The antenna array 90 is straight along the main dimension of the antenna array. In this specific embodiment of the antenna array 90 having a curved surface, the radiator elements 24 of each antenna array point to the same direction. This arrangement provides a condition for estimating the characteristics of the far-field radiation pattern such that the contributions of the individual radiators are distinguishable from those of the antenna array. In this particular embodiment of Figures 17 and 18, the purpose of the curved surface is to form a pattern in cross-section in the plane of the array to provide a compact arrangement of multiple antenna arrays around a central mounting structure. For two or more antenna arrays, the signal interface for each array can be independent to give sector coverage; alternatively, the signals corresponding to each array can be further combined to give broad sector coverage or omni-directional coverage.

19A and 19B illustrate perspective views of the antenna array 100 curved along the array direction. In the embodiment 100 shown in Figure 19A, the antenna array conforms to the shape 102 of a cylindrical substrate. In the embodiment 100' shown in Figure 19B, the array has a non-uniform curvature relative to the uniform curvature cylindrical substrate 102 described above. In this particular embodiment, each individual array radiator element 24 points in a different direction. This overall situation is beneficial for providing wide sector coverage or omni-directional coverage. The pattern is shaped to distribute signals to individual radiator elements 24 with non-uniform amplitude values and/or relative phase values.

FIG. 20 schematically illustrates the application of a pair of curved antenna arrays 110 of the present invention in a base station environment. Figure 20 shows two arrays 110 each having a non-planar portion 112. Embodiment 110 provides coverage that focuses on the areas on both sides of the mounting structure, while providing a portion of the energy directed upwards of the mounting structure. This is particularly important in providing shaped waves to cover the above, since it is often desired to communicate with an aircraft from the ground, requiring maximum antenna directivity near the horizon while simultaneously requiring maximum antenna directivity in the zenith direction of the mounting structure. a continuous coverage area. The array 110 can be mounted on the top of the cell mast 14' and includes an arched upper end 112, as shown by the curved antenna 18 in FIG.

Referring now to FIG. 21, a method 120 for fabricating a first embodiment of the antenna array of the present invention is shown. Referring to FIG. 5, an embodiment of manufacturing the antenna array 20 will first be described. In step 122 , the metal layer 60 is first bonded to the carrier medium layer 27 by using the adhesive layer 62 . Then, at step 124 , the carrier medium layer 27 is bonded to the foam core medium layer 28 using the adhesive layer 30 . Dielectric layer 27 is typically a thin carrier layer for metal layer 60 to be applied, while dielectric layer 28 provides the required dielectric spacing or thickness for radiator unit 24 to function properly.

Then, at step 126 , adhesive layer 32 is bonded to dielectric layer 28 to form stack or sandwich structure 34 . Adhesive layer 32 is preferably a double sided media tape with a release layer (not shown) on the opposite side of adhesive layer 28 . Then, in step 128 , by etching out the required radiator pattern, it is desirable to form the antenna powering unit, that is, the radiator unit 24 and the feeding circuit 26 on the metal layer 60 . The process generally includes trimming the stack 34 in a conventional manner after the etching step. Then, at step 130, the stack 34 on which the radiator unit 24 and the feed circuit 26 have been formed is bonded to the base layer 35 by means of an adhesive layer by removing the release layer. The RF connector 46 is mechanically attached to the conductive support 35 and then soldered to the metal layer 60 so that they have a proper electrical connection. As shown in Figure 3, optional step 132 may be added as remaining mechanical units are added as needed to complete the final protective cover or radome assembly 40. Powered cells 24 and circuitry 26 may also be formed after step 122, if desired.

Referring now to FIG. 22, a method for fabricating another antenna array embodiment of the present invention is shown. Referring to FIG. 11 , an example of manufacturing an antenna array 70 will be described. In process 140 , first steps 122 to 130 in method 120 may be repeated. At step 142 , metal layer 60 is bonded to carrier medium layer 27 using adhesive layer 62 . Then, at step 144 , the carrier medium layer 27 is bonded to the foam core medium layer 28 using the adhesive layer 30 . Then, at step 146 , adhesive layer 32 may be joined to foam core media layer 28 to form stack 34 . Likewise, the adhesive layer 32 is desirably a double sided media tape with a release layer (not shown) on the opposite side of the foam core layer 28 . Then, at step 148, the conductive element of the antenna, that is, the radiator element 24 and the feed circuit 26, is formed on the metal layer 60 by etching the required radiator pattern; An antenna radiator unit 24 and a feed circuit 26 . Then, at step 150 , the stack 34 on which the radiator unit 24 and the feed circuit 26 have been formed may be bonded to the conductive support 35 using the adhesive layer 32 .

As in the first alternative embodiment, at step 152 the stack 71 is formed using an adhesive layer 73 to bond the metal layer resulting in the passive radiator element 72 to the thin carrier dielectric layer 74 . In step 154 , the passive elements are etched on the metal layer to form respective radiator wires 72 . Then, at step 156 , carrier dielectric layer 74 in stack 71 is bonded to dielectric layer 76 using adhesive layer 78 . Then, at step 158 , the dielectric layer 76 is bonded to the stack 34 by bonding the dielectric layer 76 on top of the corresponding radiator unit 24 in the stack 22 using the adhesive layer 80 . Likewise, the RF connector 46 is mechanically attached to the conductive support 35 and then soldered to the metal layer 60 so that they have a proper electrical connection. As above, when required, the remaining mechanical units are added as shown in FIG. 9 to complete the final protective cover or radome assembly 40, thus adding optional step 160.

In another alternative embodiment, the radiator unit 72 can also be bonded directly to the dielectric layer 76, so that the carrier dielectric 74 and the etching step 154 are omitted. In this embodiment, after step 150, individual radiator elements are formed in step 162 by laser or punch cutting methods. Then, at step 164 , the passive radiator elements 72 are bonded to the dielectric layer 76 one by one. The remaining steps are then the same step 158 and optional step 160 as the steps described above.

In the above discussion, the base layer is just another metal sheet like the metal conductive layer 60, which can replace the rigid conductive support 35. In this embodiment, as shown on FIGS. 23-25 , the stack 34 or 82 with substrate sheets is supported by a non-conductive body such as a radome 170 . The radome 170 may be welded or mechanically assembled from multiple components, or may be a unitary stamped and formed unit, or may be formed from a single piece of material as shown. In forming the radome 170, the same or similar materials as the radome cover 42 may be used. While any number of configurations are possible for the support of stack 34 or 82 , radome 170 utilizes a pair of opposing slots 172 and 174 formed in opposing sidewalls 176 and 178 of radome 170 . Side walls 176 and 178 are adjacent to top cover 186 or are integral with top cover 180 . The top cover 180 is shown in the shape of an arch, but it can also be a flat shape or other shapes as required. Side walls 176 and 178 in turn abut or are integrally formed with bottom cover 182 . Likewise, the bottom cover 182, although shown as having a planar shape, may have other shapes as desired. Stack 82 is shown mounted within slots 172 and 174 of radome 170 . Preferably, the stack 34 or 82 is slid into the radome 170 (shown in FIG. 25 ) by means of the sheet metal back plate 35, and then the ends of the opening are covered with end caps (not shown) similar to the end cap 44. . If desired, one or more supports 184 may be included on the bottom cover 182 formed or mounted within the bottom cover 182 (shown as a pair of supports 184 ) to help support the stack 34 or 82 .

As mentioned above, the low-cost antenna array design of the present invention uses various low-cost components suitable for printed circuit board manufacturing technology, they can be assembled together in a short time, and only a small amount or no adjustment is required after assembly. get the desired performance.

Although the present invention has been described with several preferred embodiments, it will be readily understood by those skilled in the art that many modifications, additions and deletions can be made to the illustrated and disclosed invention without departing from the invention spirit and scope. For example, although, for antenna array 70, only one passive radiator element 76 is shown on radiator element 72, one or more sets of passive radiator elements may be added to antenna array 70 as desired. Foam core layer 28 and foam layer 76 are shown as a unitary structure, but may also be a multi-layer or laminated structure welded using heat or ultrasonic techniques, and together there may be two or more foam core layers. Additionally, when combined with a curved base layer, the foam core layer 28 and foam layer 76 can be assembled from linear or planar cut pieces into a conforming or "curved" pattern rather than a continuously curved structure. Thus, for substantially continuously curved portions of the substrate, the foam core layer 28 and foam layer 76 may be formed in a patchwork, linear or planar assembled configuration.

Claims (52)

1. aerial array with sandwich construction comprises:

Metal level has a plurality of antenna radiator unit that power up, and is formed with feed element therein;

The first thin carrier dielectric layer, described metal level are formed on the described first thin carrier dielectric layer;

Foam core layer has top surface and lower surface, and wherein, the described first thin carrier dielectric layer is formed on the described top surface of described foam core layer; And

Adhesive layer is formed on the described lower surface of described foam core layer, and wherein, described adhesive layer is adhered on the metallic substrate layer.

2. the aerial array in the claim 1, wherein, described metal level joins on the described first thin carrier dielectric layer with adhesive means.

3. the aerial array of claim 1, wherein, the described first thin carrier dielectric layer is adhered on the described foam core layer with adhesive means.

4. the aerial array of claim 1, wherein, described metallic substrate layer is a thin metal level.

5. the aerial array of claim 4 further comprises a nonconducting radome covered structure, seals each layer that antenna is stated in the residence, and described each layer provided support.

6. the aerial array of claim 1 comprises that further to make described each layer of antenna bonded to each other with adhesive means.

7. the aerial array of claim 1 further comprises a radome covered structure, seals each layer that antenna is stated in the residence.

8. the aerial array of claim 1, wherein, at least a portion is formed on the curved surface basalis in described a plurality of antenna stacks.

9. the aerial array of claim 8, wherein, each layer of described a plurality of antenna stacks is formed on the curved surface basalis.

10. the aerial array of claim 8, wherein, described foam core layer forms curve form, to be fit to described curved surface basalis.

11. the aerial array of claim 1, wherein, described metallic substrate layer comes down to the metal level of a rigid support.

12. the aerial array of claim 1, further comprise at least one second dielectric layer, be formed on the described metal level, there are a plurality of parasitic elements to be formed at the top surface of described second dielectric layer, wherein, between corresponding each radiator elements electric coupling is arranged in described each parasitic elements and the described metal level.

13. the aerial array of claim 12 further is included in the second thin carrier dielectric layer top surface and is formed with described a plurality of parasitic elements, is formed with the described second thin carrier dielectric layer on described second dielectric layer.

14. the aerial array of claim 12 comprises that further to make described each layer bonded to each other with adhesive means.

15. the aerial array of claim 12 further comprises the radome covered structure, seals each layer that antenna is stated in the residence.

16. the aerial array of claim 12, wherein, described metallic substrate layer is a thin metal level.

17. the aerial array of claim 16 further comprises nonconducting radome covered structure, seals each layer that antenna is stated in the residence, and the support to described each layer of antenna is provided.

18. the aerial array of claim 12, wherein, at least a portion is formed on the curved surface basalis in described a plurality of antenna stacks.

19. the aerial array of claim 18, wherein, each layer of described a plurality of antenna stacks is formed by flexible material, to conform to described curved surface basalis.

20. the aerial array of claim 18, wherein, described foam core layer forms curve form, to be fit to described curved surface basalis.

21. the aerial array of claim 12, wherein, described metallic substrate layer comes down to the metal level of a rigid support.

22. the aerial array with a plurality of layers comprises:

Metal level has a plurality of antenna radiator unit that power up, and is formed with feed element therein;

The first thin carrier dielectric layer, described metal level are formed on the described first thin carrier dielectric layer;

Foam core layer has top surface and lower surface, and wherein, the described first thin carrier dielectric layer is formed on the described top surface of described foam core layer;

At least one second dielectric layer is formed on the described metal level; And

A plurality of parasitic elements, be formed at the top surface of the second thin carrier dielectric layer, wherein, between corresponding each radiator elements electric coupling is arranged in described a plurality of parasitic elements and the described metal level, the described second thin carrier dielectric layer is formed on described second dielectric layer, and wherein, described each layer is bonded to each other and form and pile up, adhesive layer is formed on the lower surface of the described foam core layer in described the piling up, and wherein by adhesive layer described piling up is adhered on the metallic substrate layer.

23. the aerial array of claim 22 further comprises the radome covered structure, seals each layer that antenna is stated in the residence.

24. the aerial array of claim 22, wherein, described metallic substrate layer is a thin metal level.

25. the aerial array of claim 24 further comprises nonconducting radome covered structure, seals each layer that antenna is stated in the residence, and the support to described each layer of antenna is provided.

26. the aerial array of claim 22, wherein, at least a portion is formed on the curved surface basalis in described a plurality of antenna stacks.

27. the aerial array of claim 26, wherein, each layer of described a plurality of antenna stacks is formed by flexible material, to conform to described curved surface basalis.

28. the aerial array of claim 26, wherein, described foam core layer forms curve form, with suitable described curved surface basalis.

29. the aerial array of claim 22, wherein, described metallic substrate layer comes down to the metal level of a rigid support.

30. a method of making aerial array comprises step:

Form a foam core layer with top and lower surface;

A bonding metal level on the first thin carrier dielectric layer, and the described first thin carrier dielectric layer is adhered on the described top surface of described foam core layer;

On the described lower surface of described foam core layer, apply adhesive layer;

On described metal level, etch a plurality of radiator elements and feed element; And

Form metallic substrate layer, utilize described adhesive layer to make described foam core layer, the described first thin carrier dielectric layer and described metal level and described metallic substrate layer are bonding.

31. the method for claim 30 further comprises step, and described each layer of antenna is encapsulated in the radome covering.

32. the method for claim 30 further comprises step, makes a thin metal level form described metallic substrate layer.

33. the method for claim 32 further comprises step, forms a nonconducting radome covered structure so that the support to described each layer of antenna to be provided, and described each layer of antenna sealed and be supported in the described radome covered structure.

34. the method for claim 30, include make in these a plurality of antenna stacks at least a portion be formed at a step on the curved surface basalis.

35. the method for claim 34, include make described a plurality of antenna stack each layer formation from a kind of flexible material and make described each layer of antenna accord with the step of described curved surface basalis shape.

36. the method for claim 34 includes and makes described foam core layer form curve form to be fit to the step of described curved surface basalis.

37. the method for claim 30 includes and makes described metallic substrate layer form the metal level of rigid in fact support to be used for the step of described each layer of antenna.

38. the method for claim 30, further comprise step, at least one second dielectric layer is adhered on the described metal level, and form a plurality of parasitic elements at the top surface of described second dielectric layer, they and be formed in the described metal level and between each corresponding radiator elements electric coupling arranged.

39. the method for claim 38 further comprises step, forms described a plurality of parasitic elements at second top surface that approaches carrier dielectric layer, and the described second thin carrier dielectric layer is adhered on described second dielectric layer.

40. the method for claim 38 further comprises making described each layer of antenna be encapsulated into the interior step of radome covered structure.

41. the method for claim 38 includes and makes that at least a portion is formed at a step on the curved surface basalis in described a plurality of antenna stack.

42. the method for claim 41, include make described a plurality of antenna stack each layer formation from a kind of flexible material and make described each layer of antenna accord with the step of described curved surface basalis shape.

43. the method for claim 41 includes and makes described foam core layer form curve form to be fit to the step of described curved surface substrate sheet.

44. the method for claim 38 includes and makes described metallic substrate layer form the metal level of rigid in fact support to be used for the step of described each layer of antenna.

45. a method of making aerial array comprises step:

Form a foam core layer with top and lower surface;

A bonding metal level on the first thin carrier dielectric layer, and the described first thin carrier dielectric layer is adhered on the described top surface of described foam core layer;

On the described lower surface of described foam core layer, apply adhesive layer;

On described metal level, etch a plurality of radiator elements and feed element;

Form metallic substrate layer, utilize described adhesive layer to make described foam core layer, the described first thin carrier dielectric layer and described metal level and described metallic substrate layer are bonding;

At least one second dielectric layer is adhered on described metal level radiator elements and the feed element; And

Top surface at described second dielectric layer forms a plurality of parasitic elements.

46. the method for claim 45 further comprises step, and described aerial array is encapsulated in the radome covering.

47. the method for claim 45 further comprises step, described metallic substrate layer forms from a thin metal level.

48. the method for claim 45 further comprises step, forms nonconducting radome covered structure, in order to support and to seal each layer of described antenna in the described radome covered structure.

49. the method for claim 45 includes and makes that at least a portion is formed at a step on the curved surface basalis in described a plurality of antenna stack.

50. the method for claim 49 includes each layer formation of making described a plurality of antenna stack from a kind of flexible material and make each layer of described antenna comply with the step of described curved surface basalis shape.

51. the method for claim 49 includes and makes described foam core layer form the step of the suitable described curved surface basalis of curve form.

52. the method for claim 45 includes and makes described metallic substrate layer form the metal level of rigid in fact support to be used for the step of described each layer of antenna.

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