Patent Publication Number: US-8525729-B1

Title: Antenna tiles with ground cavities integrated into support structure

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims the benefit of priority under 35 U.S.C. §119 from U.S. Provisional Patent Application Ser. No. 61/143,720, entitled “LOW COST LOW MASS RF-ON-FLEX L-BAND PHASED ARRAY SPACE TILE,” filed on Jan. 9, 2009, which is hereby incorporated by reference in its entirety for all purposes. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     The invention was made with Government support, and the Government has certain rights in the invention by the terms of Contract No. FA8650-07-C-1100 awarded by the Department of the Air Force. 
    
    
     BACKGROUND 
     Antenna systems may be assembled using a phased array, which is a group of antennas in which the relative phases of the respective signals feeding the antennas are varied in such a way that the effective radiation pattern of the array is reinforced in a desired direction and suppressed in undesired directions. A phased array of an antenna system may include building blocks sometimes referred to as tiles. These tiles, however, are generally not considered to be a viable business option, due to the prohibitive manufacturing expenses and the excessive mass of tile designs. 
     SUMMARY 
     In one aspect of the disclosure, integrating resonating ground cavities of patch radiating elements into a support structure of an antenna tile may result in significant improvements in antenna performance, assembly cost and time, and mass of the antenna tile. 
     In one aspect of the disclosure, an antenna tile may comprise one or more antenna patch elements, a circuit board, and a support structure. The one or more antenna patch elements may radiate radio frequency (RF) signals, and each of the one or more antenna patch elements may comprise a conductive layer. The circuit board may be disposed between the one or more antenna patch elements and the support structure. The support structure may comprise one or more ground cavities. The one or more ground cavities may be integrated into the support structure and may be electrically conductive. The one or more ground cavities may resonate standing waves, and the one or more ground cavities may be disposed below the respective one or more antenna patch elements. 
     In another aspect of the disclosure, a method of manufacturing an antenna tile may comprise one or more of the following: providing one or more antenna patch elements; providing a circuit board; providing a support structure comprising one or more ground cavities; attaching the circuit board to the support structure; and attaching the one or more antenna patch elements to the circuit board. Each of the one or more antenna patch elements may comprise a conductive layer. The one or more ground cavities may be integrated into the support structure and may be electrically conductive. The one or more ground cavities may resonate standing waves. The one or more ground cavities may be disposed below the respective one or more antenna patch elements. 
     It is understood that other configurations of the subject technology will become readily apparent to those skilled in the art from the following detailed description, wherein various configurations of the subject technology are shown and described by way of illustration. As will be realized, the subject technology is capable of other and different configurations and its several details are capable of modification in various other respects, all without departing from the scope of the subject technology. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is an exploded view illustrating an example of an antenna tile, as seen from the top side of the antenna tile. 
         FIG. 1B  is a simplified view illustrating an example of an antenna tile, as seen from the top side of the antenna tile. 
         FIG. 1C  is an exploded view illustrating an example of an antenna tile, as seen from the bottom side of the antenna tile. 
         FIG. 2  is a simplified sectional view illustrating an example of an antenna tile, as seen from a side of the antenna tile. 
         FIG. 3  is a view illustrating an example of an antenna tile, as seen from the top side of the antenna tile. 
         FIG. 4  is a view illustrating an example of an antenna tile without patch elements, as seen from the top side of the antenna tile. 
         FIG. 5  is a view illustrating an example of a circuit board of an antenna tile, as seen from the bottom side of the circuit board. 
         FIG. 6  is a view illustrating an example of a support structure of an antenna tile, as seen from the top side of the support structure. 
         FIG. 7  is a simplified sectional view illustrating an example of an antenna tile, as seen from a side of the antenna tile. 
         FIG. 8  is a simplified view illustrating an example of a support structure of an antenna tile, as seen from the top side of the support structure. 
         FIG. 9  is a view illustrating an example of a support structure of an antenna tile, as seen from the bottom side of the support structure. 
         FIG. 10  is a view illustrating an example of a circuit board for an antenna tile, as seen from a side of the circuit board. 
         FIG. 11  is a view illustrating an example of a circuit board for an antenna tile, as seen from a side of the circuit board. 
         FIG. 12  is a view illustrating an example of a frame on which an antenna tile is mounted, as seen from the top side of the frame. 
         FIG. 13  is a view illustrating an example of a panel on which framed antenna tiles are mounted, as seen from the top side of the panel. 
         FIG. 14  is a view illustrating an example of a circuit board for an antenna tile, as seen from the bottom side of the circuit board. 
         FIG. 15  is a view illustrating an example of a support structure for an antenna tile, as seen from the top side of the support structure. 
         FIG. 16A  is a view illustrating an example of an antenna tile seen from the top side of the antenna tile. 
         FIG. 16B  is a view illustrating an example of a circuit board for an antenna tile, as seen from the bottom side of the circuit board. 
         FIG. 16C  is a view illustrating an example of a support structure for an antenna tile, as seen from the top side of the support structure. 
         FIG. 17  illustrates an example of return loss plots for an antenna tile constructed using a technique described with reference to  FIGS. 16A-16C . 
         FIG. 18  illustrates an example of return loss plots of an antenna tile constructed using a technique described with reference to  FIGS. 3-6 . 
     
    
    
     DETAILED DESCRIPTION 
     The detailed description set forth below is intended as a description of various configurations of the subject technology and is not intended to represent the only configurations in which the subject technology may be practiced. The appended drawings are incorporated herein and constitute a part of the detailed description. The detailed description includes specific details for the purpose of providing a thorough understanding of the subject technology. However, it will be apparent to those skilled in the art that the subject technology may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring the concepts of the subject technology. Like or similar components are labeled with identical element numbers for ease of understanding. 
       FIG. 1A  is an exploded view illustrating an example of an antenna tile seen from the top side of the antenna tile.  FIG. 1B  illustrates a simplified top-down view of the antenna tile shown in  FIG. 1A .  FIG. 1C  is an exploded view of the antenna tile shown in  FIG. 1A , as seen from the bottom side of the antenna tile. An antenna tile  100  (sometimes referred to as a tile) may include one or more antenna patch elements  110  (sometimes referred to as patch elements or radiating elements). In this example, six antenna patch elements are shown. The antenna tile  110  may also include a circuit board  130  and a support structure  150 . 
     In one example, each of the antenna patch elements  110  may have a top surface and a bottom surface and may include (i) a conductive layer  111  (e.g., a metal such as copper) having a top surface  111   a  and a bottom surface  111   b  and optionally (ii) a dielectric layer  112  (e.g., a foam dielectric) having a top surface  112   a  and a bottom surface  112   b . Antenna patch elements  110  may be used to radiate signals such as radio frequency (RF) signals (e.g., L-band RF signals). A dielectric layer  112  may be used to physically support its respective conductive layer  111 . A circuit board  130  may have a top surface  130   a  and a bottom surface  130   b  and may include one or more circuit modules  131 . A support structure  150  may have a top surface  150   a  and a bottom surface  150   b  and may include one or more ground cavities  151  and optionally one or more module cavities  152 . In this embodiment, a ground cavity  151  is electrically conductive and includes a metal layer (e.g., copper). In one configuration, each of the components  110 ,  111 ,  112 ,  130 , and  150  is generally planar. 
       FIG. 2  is a simplified sectional view illustrating an example of an antenna tile seen from a side of the antenna tile. In one example, the size W 1  of a dielectric layer  112  may be larger than the size W 2  of a ground cavity  151 . In another example, W 1  may be the same as or smaller than W 2 . 
     A support structure  150  may include an inner structure  154 . In one advantageous configuration, an inner structure  154  may include a perforated honeycomb structure and may be conductive (e.g., comprised of a metal such as aluminum). A support structure  150  may also include a top face sheet  153  and/or a bottom face sheet  155 . Each of the face sheets may be, for example, a conductive layer (e.g., a metal such as aluminum). In this example, each of the inner structure and the face sheets is electrically and thermally conductive. An inner structure may be, for example, about 0.2 to 0.4 inches thick. Each face sheet may be, for example, about 0.01 to 0.02 inches thick. 
       FIG. 3  is a view illustrating an example of an antenna tile seen from the top side of the antenna tile. In this example, six antenna patch elements  110  are disposed on top of a circuit board  130 . In one configuration, the top surface of the circuit board  130  is generally planar, and there is substantially no protrusion extending vertically in the areas not covered by the patch elements  110 . While the top surface of the circuit board  130  may have some height variations due to irregularity caused by, for example, underlying circuit traces or solder traces, the height variation may be much smaller than the height of the antenna patch elements (e.g., 3 to 30 times less or any number in-between). 
       FIG. 4  shows a circuit board  130  prior to attaching patch elements  110 , as seen from the top side of the circuit board. A circuit board  130  may include one or more top islands  132   a  and a top face sheet  132   b  on the top surface. In this example, six top islands  132   a  are shown, each corresponding to its respective patch element  110 . A top island  132   a  may be a conductive layer. In another example, a top island  132   a  may be a non-conductive layer (e.g., dielectric). A top face sheet  132   b  may be, for example, a conductive layer, which may be a ground layer. In one example, no circuit modules are attached to the top side of the circuit board  130 . 
       FIG. 5  is a view illustrating an example of a circuit board  130  seen from the bottom side of the circuit board. A circuit board  130  may include, on its bottom surface, one or more bottom islands  133 , one or more bottom rims  134 , one or more circuit modules  131 , and one or more conductive regions  135 . In this example, six bottom islands  133  are shown, each for mating with its corresponding patch element  110  and corresponding ground cavity  151 . A bottom island  133  may be a non-conductive layer (e.g., dielectric). In this example, six bottom rims  134  are shown, each for its corresponding ground cavity  151 . A bottom rim  134  may be conductive (e.g., comprised of a metal such as copper). A conductive region  135  may be used for ground and may be made of a metal such copper. A circuit board  130  may also include one or more connectors such as coaxial connectors  136   a  (e.g., for radio frequency (RF) signals) and control signal connectors  136   b  (e.g., digital control/data signals). These connectors may carry signals to and from the circuit modules. 
     A circuit module  131  may include one or more of the following: a transmitter (T), a receiver (R), and/or a transceiver. These are sometimes referred to as a T/R module (as shown in  FIG. 2 ). A circuit module  131  may also include one or more of the following: a driver module, a switch module, capacitors, resistors, and/or temperature sensors. A circuit module  131  may include analog circuits, digital circuits and/or a combination of both. In one advantageous configuration, a circuit module may be a low mass, low cost quad flat-pack no-lead (QFN) plastic encapsulated module (PEM) radio frequency (RF) module package. 
       FIG. 6  is a view illustrating an example of a support structure seen from the top side of the support structure. A support structure  150  may include, on its top surface, one or more ground cavities  151 . A support structure  150  may also include one or more module cavities  152 , a top face sheet  153  and/or a bottom face sheet (e.g.,  155  in  FIG. 2 ). In this example, six ground cavities  151  are shown, each for mating with its corresponding patch element  110 . Each of the module cavities  152  may also mate with its respective circuit module  131 . 
     A support structure  150  may also include one or more access openings  156  for connectors (e.g.,  136   a ,  136   b  in  FIG. 5 ). An access opening  156  may provide a hole through the entire thickness of the support structure, and its rim  156   b  (and its side wall) may be coated with a dielectric layer (e.g., Kapton®). A support structure  150  may also have a strip of a dielectric layer along the top edge  159   b  of the support structure. 
     In the embodiment shown in  FIG. 6 , a support structure  150  may include one or more first physical pockets  151   a  formed on the top surface (as opposed to the bottom surface of the support structure  150 ). Each of the ground cavities  151  may be comprised of a conducive layer  151   c  (e.g., a metal sheet such as a copper foil) that is integrally attached to a respective one of the first physical pockets  151   a  and to a rim  151   b  of the respective one of the first physical pockets  151   a . An adhesive  170   f  (see  FIG. 2 ) such as a conductive sheet adhesive with a release liner may be used to attach the conductive layer  151   c  to the pocket and its rim. When assembled, the conductive layer on the rim  151   b  mates with its corresponding bottom rim  134  (see  FIG. 5 ) of the circuit board  130  for electrical connection and mechanical attachment. The conductive sheet of a ground cavity  151  covers the surface of its respective physical pocket  151   a  and its rim  151   b . In one example, adhesive-backed copper-foil lined ground cavities significantly simplify the tile assembly. A ground cavity may be, for example, 2.0 to 2.5 inches (in a first horizontal direction), 2.0 to 2.5 inches (in a second horizontal direction), and 0.7 to 0.15 inches (in a vertical direction). A conductive layer  151   c  may be, for example, 0.001 to 0.003 inches thick. 
     In one aspect, an antenna tile  100  may have one common radio frequency (RF) ground. The conductive layers of ground cavities  151 , ground traces of circuit modules  131 , ground traces on/in a circuit board  130  (e.g.,  132   b  in  FIG. 4 ), and ground traces on/in a support structure  150  (e.g.,  153 ,  154  and  155  in  FIG. 2 ) may be all connected together to the common ground. 
     In this embodiment, a support structure  150  may also include one or more second physical pockets  152   a  formed on the top surface. Each of the module cavities  152  may be comprised of a non-conductive sheet  152   c  (e.g., a dielectric such as Kapton®) that is integrally attached to a respective one of the second physical pockets  152   a  and to a rim  152   b  of the respective one of the second physical pockets  152   a . A non-conductive sheet  152   c  may prevent machining debris. An adhesive  170   g  (see  FIG. 2 ) such as a non-conductive sheet adhesive with a release liner may be used to attach the non-conductive sheet to the pocket and its rim. When assembled, a portion of the non-conductive sheet on the rim  152   b  is attached to the bottom surface of the circuit board  130 . A non-conductive sheet  152   c  and an adhesive  170   g  together may be referred to as a non-conductive tape. 
     In the configuration shown in  FIG. 6 , the top face sheet  153  does not cover up the conductive layers  151   c , the dielectric layers  152   c  or the openings  156 . In this example, the top face sheet  153  does not cover up any of the layers on the rims or edges (e.g., the dielectric layer on the rim  156   b , the dielectric layer on the rim  152   b , the dielectric layer on the top edge  159   b  of the support structure  150 , or the conductive layer on the rim  151   b ). 
       FIG. 7  is a simplified sectional view illustrating an example of an antenna tile seen from a side of the antenna tile. In one example, a support structure  150  may be about 0.3 to 0.4 inches thick, and an antenna tile  100  may be about 0.9 to 1 inch thick. These are simply examples, and the subject technology is not limited to these examples. 
       FIG. 8  is a simplified view illustrating an example of a support structure seen from the top side of the support structure.  FIG. 9  is a view illustrating an example of a support structure seen from the bottom side of the support structure. A support structure  150  may include, on its bottom surface, inserts  157 . In this example, four inserts  157  are centered in the support structure&#39;s edges to provide stable mounting of the support structure to its respective frame (e.g.,  160  in  FIG. 12 ) while allowing an antenna tile (e.g.,  100 ) to be thermally decoupled from the frame. 
       FIG. 10  is a view illustrating an example of a circuit board seen from a side of the circuit board. A circuit board  130  in  FIG. 10  may be a multi-layer flexible circuit board. A flexible circuit board  130  may include a solder mask layer, multiple metal layers (e.g., copper), multiple dielectric layers (e.g., Kapton®), one or more adhesive layers, and a cover layer (e.g., Kapton®). In one aspect, it is advantageous to use a flexible circuit board. The dielectric constant of a dielectric layer in  FIG. 10  may be, for example, 3.4, and the loss tangent may be, for example, 0.003. 
       FIG. 11  is a view illustrating an example of another circuit board seen from a side of the circuit board. A circuit board  130  in  FIG. 11  may be a multi-layer rigid circuit board. A rigid circuit board  130  may include one or more solder mask layers, multiple metal layers (e.g., copper), multiple dielectric layers, and one or more adhesive layers. A dielectric layer in a rigid circuit board may be made rigid by incorporating (or being reinforced with) particles such as fabric or glass weaves. The dielectric constant of a dielectric layer in  FIG. 11  may be, for example, 2.94, and the loss tangent may be, for example, 0.0015. While  FIGS. 10 and 11  illustrate multi-layer circuit boards, the subject technology is not limited to multi-layer boards. 
     Referring to  FIGS. 1A through 11 , in one configuration, one or more antenna patch elements  110  are disposed above, and vertically aligned with, respective one or more top islands  132   a  ( FIG. 4 ), respective one or more bottom islands  133  ( FIG. 5 ), and respective one or more ground cavities  151 . The one or more antenna patch elements may be capacitively coupled with respective one or more ground cavities. In one configuration, one or more circuit modules  131  are disposed above, and vertically aligned with, respective one or more module cavities  152 . In one configuration, one or more bottom rims  134  on a circuit board  130  are disposed above, attached to, and vertically aligned with, respective one or more rims  151   b  on a support structure  150 . 
       FIG. 12  is a view illustrating an example of a frame on which an antenna tile is mounted, as seen from the top side of the frame. An antenna tile  100  with patch elements  110  may be mounted on a frame  160 . A frame may be comprised of, for example, graphite composite material. 
       FIG. 13  is a view illustrating an example of a panel on which framed antenna tiles are mounted, as seen from the top side of the panel. An array of frames  160 , each with its antenna tile  100 , may be mounted on a panel  200 . In one example, a horizontal pitch DX 1  among patch elements  110  on a tile  100  may be made constant. A vertical pitch DY 1  among patch elements  110  on a tile  100  may be also made constant. A horizontal pitch DX 2  among patch elements  110  across different tiles  100  may be also made constant. A vertical pitch DY 2  among patch elements  110  across different tiles  100  may be also made constant. In one example, DX 1 , DY 1 , DX 2  and DY 2  may be equal. In another example, one or more of DX 1 , DY 1 , DX 2  and DY 2  may be made different. When a patch element pattern is centered on a tile, this allows 180 degree tile rotation in a panel. 
     Various additional or alternative configurations of the subject technology are described below. In one configuration, each of one or more antenna patch elements may include a conductive layer (e.g.,  111  in  FIG. 1A ) but without a dielectric layer. In this case, the conductive layer of an antenna patch element may be attached directly (without a dielectric layer) to a circuit board (e.g.,  130 ). Furthermore, in one aspect, a conductive layer of an antenna patch element may be made into (and thus integrated into) a circuit board as one of the top metal layers during the manufacturing process of the circuit board. While square-shaped patch elements are shown in  FIG. 3 , a patch element may have other shapes. 
     In one configuration, a support structure (e.g.,  150 ) may be a solid piece rather than having a honeycomb structure. In another configuration, a support structure does not have a top face sheet and/or a bottom face sheet. In yet another configuration, a support structure and any of its components (e.g., any face sheet or inner structure) may be non-conductive (e.g., electrically and/or thermally non-conductive). 
       FIGS. 14 and 15  provide other alternative configurations of the subject technology.  FIG. 14  is a view illustrating an example of a circuit board seen from the bottom side of the circuit board. A circuit board  130  in  FIG. 14  may include dielectric islands  133  and conductive rims  134  that surround the dielectric islands  133 . In one example, the circuit board in  FIG. 14  may include circuit modules and connectors. 
       FIG. 15  is a view illustrating an example of a support structure seen from the top side of the support structure. A support structure  150  in  FIG. 15  may include ground cavities  151 , cavities or openings  158 , a face sheet  153 , and connector openings  156 . In comparison to the support structure shown in  FIG. 6 , the support structure in  FIG. 15  does not include dielectric cavities. The cavities  158  may be provided to keep clear of the components that may be on the bottom side of a circuit board. In one example, a support structure  150  in  FIG. 15  may be used for a passive tile. 
       FIGS. 16A ,  16 B and  16 C illustrate an antenna tile constructed according to another approach.  FIG. 16A  is a view illustrating an example of an antenna tile seen from the top side of the antenna tile;  FIG. 16B  is a view illustrating an example of a circuit board seen from the bottom side of the circuit board; and  FIG. 16C  is a view illustrating an example of a support structure seen from the top side of the support structure. In  FIGS. 16A-16C , an antenna tile  300  may include patch elements  310 , a circuit board  330  and a support structure  350 . The patch elements  310  may be placed on the top surface of a circuit board  330 , and the bottom surface of the circuit board  330  may be attached to the top surface of the support structure  350 . The antenna tile  300  may also include five-sided conductive ground boxes  333  (see  FIG. 16B ) soldered onto the bottom surface of the circuit board  330 . The process of attaching the ground boxes to the circuit board is labor intensive and costly requiring many parts. During assembly, some of the difficulties associated with soldering the five-sided ground boxes to the circuit board include the following: The ground box cavities do not remain flat during reflow and need to be weighted down. The solder joints on the interface areas of the ground boxes and the circuit board need to be touched up by hand. Cleaning solutions fill the ground box cavities, and significant bake-out time is required. 
     The support structure  350  may be a double-layer custom graphite composite structure that has first indented areas  351   a  and second indented areas  352   a . The first indented areas  351   a  may be provided to keep clear of the ground boxes  333 , and the second indented areas  352   a  may be provided to keep clear of the components  331  (e.g., circuit modules, electrical connectors) on the bottom surface of the circuit board  330 . A circuit module included in an antenna tile  300  may be a low temperature co-fired ceramic (LTCC) ball grid array (BGA) package. The first and second indented areas  351   a  are not coated with any conductive material. When assembled, the ground boxes  333  are not in contact with, and are not attached to, the support structure  350 . A gap exists between the ground boxes  333  and the first indented areas  351   a , and there is no adhesive between the ground boxes  333  and the first indented areas  351   a.    
       FIG. 17  illustrates an example of return loss plots for an antenna tile constructed with ground boxes attached to a circuit board using a technique described with reference to  FIGS. 16A-16C . Each line in  FIG. 17  is for a patch element. The return loss plots for six patch elements indicate inconsistent results with poor tracking. 
       FIG. 18  illustrates an example of return loss plots of an antenna tile constructed using a technique described with reference to, for example,  FIGS. 1A through 6 . Each line in  FIG. 18  is for a patch element. The return loss plots for six patch elements with resonant ground cavities integrated into a support structure yield more consistent results and provide better performance than that shown in  FIG. 17 . 
     Now referring back to  FIGS. 1A through 13 , an antenna tile manufacturing process is described. In one example, antenna patch elements  110 , a circuit board  130 , and a support structure  150  may be fabricated separately and then assembled together to form an antenna tile. The components  110 ,  130  and  150  may be fabricated concurrently or sequentially. 
     To fabricate antenna patch elements  110 , in one example, a large conductive sheet may be attached to a large dielectric sheet using an adhesive (e.g., a sheet adhesive), and the assembled unit may be cut to produce a plurality of small antenna patch elements  110 , each with a conductive layer  111  and a dielectric layer  112 . Alternatively, each antenna patch element  110  may be assembled individually by attaching a piece of a conductive layer to a piece of a dielectric layer using adhesive. 
     A circuit board  130  may be fabricated, for example, by assembling one or more conductive layers (e.g., metal traces, contacts, vias, islands, sheets) for carrying analog/digital control and data signals, power and/or ground, one or more dielectric layers (e.g., dielectric sheets, islands), and optionally one or more adhesive layers. One or more circuit modules may be attached to the circuit board  130 . One or more connectors for electrical signals (e.g., digital and/or analog signals, power, and ground) may be attached to the circuit board. In one configuration, one of the top metal layers on a circuit board  130  may be used as a conductive layer of one or more antenna patch elements when the patch elements do not include a dielectric layer. 
     A support structure  150  may be fabricated, for example, by providing a substrate (e.g., inner structure  154  in  FIG. 2 ), forming one or more first pockets (e.g.,  151   a ) on the substrate for respective one or more ground cavities, forming one or more second pockets (e.g.,  152   a ) for respective one or more circuit modules, and/or forming one or more opening (e.g.,  156 ) for connectors. One or more conductive sheets (e.g.,  153  and  155 ) may be formed on the top and/or bottom surfaces of the support structure by, for example, using a sheet adhesive to attach the sheets to the support structure. In addition, one or more conductive sheets (e.g., copper foil) may be provided (e.g., attached using a sheet adhesive) in the one or more first pockets and on the respective one or more rims. One or more dielectric sheets (e.g., Kapton®) may be provided (e.g., attached using a sheet adhesive) in the one or more second pockets and on the respective one or more rims. One or more dielectric layers may be also formed on the one or more rims of the openings. 
     In assembly, one or more antenna patch elements  110 , a circuit board  130 , and a support structure  150  may be provided. Each of the components  110 ,  130  and  150  may be prepared and provided concurrently or at different times or in various orders. In one example, a circuit board  130  may be attached to a support structure  150 , and then one or more antenna patch elements  110  may be attached to the circuit board  130 . In another assembly process, this order may be reversed. 
     Each of the one or more antenna patch elements may include a conductive layer and optionally a dielectric layer. A support structure  150  may include one or more ground cavities  151  that are integrated into the support structure and electrically conductive. The one or more ground cavities may be resonating cavities and may resonate standing waves. The depth of a ground cavity may be a function of the operating frequency and bandwidth. 
     The one or more ground cavities  151  may be disposed vertically below the respective one or more antenna patch elements  110 . The circuit board  130  may be disposed vertically above the support structure  150 . 
     Various components may be attached to each other using adhesives. For example, referring to  FIG. 2 , one or more antenna patch elements  110  may be attached to a circuit board  130  using an adhesive layer  170   b . A circuit board  130  may be attached to a support structure  150  using an adhesive layer  170   c . Various components within components  110 ,  130  and  150  may also be attached to one another using adhesives. For example, a conductive layer  111  may be attached to a dielectric layer  112  using an adhesive layer  170   a . A face sheet  153  may be attached to an inner structure  154  using an adhesive layer  170   d . A face sheet  155  may be attached to an inner structure  154  using an adhesive layer  170   e . An adhesive or an adhesive layer may be, for example, a sheet adhesive with a release liner (e.g., a peel-and-stick type of adhesive sheet). An adhesive may be conductive or non-conductive depending on the type of surfaces to be attached. When attaching conductive layers or surfaces, a conductive adhesive may be utilized. When attaching non-conductive layers or surfaces or when attaching one conductive layer to a non-conductive layer, a non-conductive adhesive may be utilized. For example, an adhesive layer  170   a ,  170   b  may be non-conductive. An adhesive layer  170   c  may be conductive or non-conductive. An adhesive layer  170   d ,  170   e  may be conductive when the components  153 ,  154  and  155  are conductive. An adhesive layer  170   f  between the conductive layer  151   c  and the surface of a pocket  151   a  in the support structure may be conductive. An adhesive layer  170   g  in a module cavity may be non-conductive. Conductive adhesives can provide electrical as well as thermal conduction. 
     After antenna tiles are assembled, they may be attached to a frame (e.g.,  160  in  FIG. 12 ), and a plurality of frames may be attached to a top flat surface of a panel (e.g.,  200  in  FIG. 13 ). 
     In one aspect of the disclosure, antenna tiles (e.g., one shown as tile  100  in  FIG. 1 ) may be used as modular building blocks for phased array satellite payloads (e.g., active radar phased array space tiles). Antenna tiles are generally not considered to be a viable business option, due to the prohibitive manufacturing expenses and the excessive mass of tile designs. For instance, as shown and described with reference to  FIGS. 16A-16C , tiles (e.g.,  300 ) may utilize (i) expensive customized composite honeycomb structures (e.g.,  350  in  FIG. 16C ) to meet the thermal, mass, structural, and coefficient of thermal expansion (CTE) requirements of space missions, (ii) heavy, costly, rigid multi-layer printed circuit boards (MLB) (e.g.,  330  in  FIG. 16B ) to provide the radio frequency (RF) interconnect, and (iii) separate (i.e., not integrated) five-sided ground-resonating cavity boxes (e.g.,  333  in  FIG. 16B ) for patch elements. These five-sided boxes add cost and are not conducive to the desired automated assembly process. In this regard, tile designs utilizing rigid printed wiring boards (PWBs) and heavy/costly support structures are expensive to produce. 
     In one aspect of the present disclosure, the tile design of the subject technology can significantly reduce the overall tile mass and cost while improving the tile thermal efficiency. For example, changing from custom composite support structure to stock aluminum honeycomb support structure can result in 90% reduction in support structure cost. Integrating the ground cavity into the support structure results in part count reduction and process simplification. Accordingly, the entire tile can be fully assembled using automated equipment. 
     In one aspect, the cost and mass of an antenna tile of the subject technology (e.g., an L-band tile) is significantly reduced by (i) changing the tile cross-section so that the main thermal path no longer relies on coupling the back side of circuit modules to an inner face sheet layer of the support structure; (ii) integrating the resonating antenna ground cavities into the support structure, thus eliminating an additional part and process step; (iii) changing from costly customized support structure to more affordable all-aluminum stock honeycomb support structure; and/or (iv) utilizing flexible polyimide printed circuits instead of rigid MLBs. 
     In one aspect of the disclosure, an antenna tile such as a tile  100  in  FIG. 3  offers many design enhancements over a tile such as a tile  300  in  FIG. 16A . For example, in one configuration, a tile  100  uses a low mass, low cost quad flat-pack no-lead (QFN) plastic encapsulated module (PEM) radio frequency (RF) module package for a circuit module rather than an expensive, heavy low temperature co-fired ceramic (LTCC) ball grid array (BGA) package. 
     In one configuration, a tile  100  uses a low cost stock aluminum honeycomb panel as a support structure (e.g.,  150 ) rather than a double-layer custom graphite composite structure. In one configuration, a tile  100  includes lining honeycomb ground cavities with copper foil. This eliminates the need for separate five-sided copper ground boxes. When integrated ground cavities are used, a circuit board (e.g.,  130 ) can be attached to a support structure (e.g.,  150 ) as received. No soldering is needed to provide ground cavities. Ground cavities for antenna patch elements are formed, for example, by copper foils lining in the support structure when the circuit board is attached to the support structure. 
     In one configuration, a tile  100  uses a sheet adhesive with a release liner to attach a flexible circuit board (e.g.,  130 ) to a honeycomb support structure (e.g.,  150 ). This eliminates the need for a heavy screened-on-paste adhesive. In one configuration, a patch element pattern is centered on a tile, and this allows 180 degree tile rotation in a panel. In one configuration, the tile size is reduced to allow nesting of tiles into a frame. 
     In one configuration, ground cavities (e.g.,  151  in  FIG. 6 ) of the subject technology have no shape separate and apart from the structural shape provided by the physical pockets of a support structure  150 . Thin conductive layers such as a copper foil have no shape by themselves. The structural shape of the ground cavities is formed when the conductive layers are integrated into the support structure by attachment to the physical pockets in the support structure. The five-sided ground boxes  333  in  FIG. 16B , on the other hand, have a definitive structural shape independently of the support structure  350  and the circuit board  330 . The structural shape of the five-sided ground boxes exists independently of any other structure. 
     In one aspect of the disclosure, integrating resonating ground cavities (e.g.,  151 ) of patch radiating elements (e.g.,  110 ) into a support structure (e.g.,  150 ) results in significant improvements in (i) antenna performance, (ii) assembly cost and time, and (iii) mass of the antenna tile. In one example, a cost savings of $60 per tile and a mass savings of about 2.8 grams per tile can be realized. In one example, an antenna tile (e.g.,  100 ) may weigh about 400 to 420 grams. 
     In one aspect, antenna tiles of the subject technology may be utilized in active phased array antenna systems for space, aerospace or terrestrial use. 
     It should be noted that various exemplary dimensions, numbers, materials, and structures are provided in this disclosure, but the subject technology is not limited to these examples. 
     Those of skill in the art would appreciate that various components and blocks may be arranged differently (e.g., arranged in a different order, or partitioned in a different way) all without departing from the scope of the subject technology. 
     It is understood that the specific order or hierarchy of steps in the processes disclosed is an illustration of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the processes may be rearranged. Some of the steps may be performed simultaneously. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented. 
     The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. The previous description provides various examples of the subject technology, and the subject technology is not limited to these examples. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. Pronouns in the masculine (e.g., his) include the feminine and neuter gender (e.g., her and its) and vice versa. Headings and subheadings, if any, are used for convenience only and do not limit the invention. 
     Terms such as “top,” “bottom,” “front,” “rear,” “above,” “below” and the like as used in this disclosure should be understood as referring to an arbitrary frame of reference, rather than to the ordinary gravitational frame of reference. Thus, a top surface, a bottom surface, a front surface, and a rear surface may extend upwardly, downwardly, diagonally, or horizontally in a gravitational frame of reference. Similarly, an item disposed above another item may be located above or below the other item along a vertical, horizontal or diagonal direction; and an item disposed below another item may be located below or above the other item along a vertical, horizontal or diagonal direction. 
     A phrase such as an “aspect” does not imply that such aspect is essential to the subject technology or that such aspect applies to all configurations of the subject technology. A disclosure relating to an aspect may apply to all configurations, or one or more configurations. An aspect may provide one or more examples. A phrase such as an aspect may refer to one or more aspects and vice versa. A phrase such as an “embodiment” does not imply that such embodiment is essential to the subject technology or that such embodiment applies to all configurations of the subject technology. A disclosure relating to an embodiment may apply to all embodiments, or one or more embodiments. An embodiment may provide one or more examples. A phrase such an embodiment may refer to one or more embodiments and vice versa. A phrase such as a “configuration” does not imply that such configuration is essential to the subject technology or that such configuration applies to all configurations of the subject technology. A disclosure relating to a configuration may apply to all configurations, or one or more configurations. A configuration may provide one or more examples. A phrase such a configuration may refer to one or more configurations and vice versa. 
     The word “exemplary” is used herein to mean “serving as an example or illustration.” Any aspect or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects or designs. 
     All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. §112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.” Furthermore, to the extent that the term “include,” “have,” or the like is used in the description or the claims, such term is intended to be inclusive in a manner similar to the term “comprise” as “comprise” is interpreted when employed as a transitional word in a claim.