Low profile active electronically scanned antenna (AESA) for Ka-band radar systems

A vertically integrated Ka-band active electronically scanned antenna including, among other things, a transitioning RF waveguide relocator panel located behind a radiator faceplate and an array of beam control tiles respectively coupled to one of a plurality of transceiver modules via an RF manifold. Each of the beam control tiles includes a respective plurality of high power transmit/receive (T/R) cells as well as dielectric waveguides, RF stripline and coaxial transmission line elements. The waveguide relocator panel is preferably fabricated by a diffusion bonded copper laminate stack up with dielectric filling. The beam control tiles are preferably fabricated by the use of multiple layers of low temperature co-fired ceramic (LTCC) material laminated together. The waveguide relocator panel and the beam control tiles are designed to route RF signals to and from a respective transceiver module of four transceiver modules and a quadrature array of antenna radiators matched to free space formed in the faceplate. Planar type metal spring gaskets are provided between the interfacing layers so as to provide and ensure interconnection between mutually facing waveguide ports and to prevent RF leakage from around the perimeter of the waveguide ports. Cooling of the various components is achieved by a pair of planar forced air heat sink members which are located on either side of the array of beam control tiles. DC power and control of the T/R cells is provided by a printed circuit wiring board assembly located adjacent to the array of beam controlled tiles with solderless DC connections being provided by an arrangement of “fuzz button” electrical connector elements.

BACKGROUND OF THE INVENTION

This invention relates generally to radar and communication systems and more particularly to an active phased array radar system operating in the Ka-band above 30 GHz.

Active electronically scanned antenna (AESA) arrays are generally well known. Such apparatus typically requires amplifier and phase shifter electronics that are spaced every half wavelength in a two dimensional array. Known prior art AESA systems have been developed at 10 GHz and below, and in such systems, array element spacing is greater than 0.8 inches and provides sufficient area for the array electronics to be laid out on a single circuit layer. However, at Ka-band (>30 GHz), element spacing must be in the order of 0.2 inches or less, which is less than 1/10 of the area of an array operating at 10 GHz.

Accordingly, previous attempts to design low profile electronically scanned antenna arrays for ground and air vehicles and operating at Ka-band have experienced what appears to be insurmountable difficulties because of the small element spacing requirements. A formidable problem also encountered was the extraction of heat from high power electronic devices that would be included in the circuits of such a high density array. For example, transmit amplifiers of transmit/receive (T/R) circuits in such systems generate large amounts of heat which much be dissipated so as to provide safe operating temperatures for the electronic devices utilized.

Because of the difficulties of the extremely small element spacing required for Ka-band operation, the present invention overcomes these inherent problems by “vertical integration” of the array electronics which is achieved by sandwiching multiple mutually parallel layers of circuit elements together against an antenna faceplate. By planarizing T/R channels, RF signal manifolds and heat sinks, the size and particularly the depth of the entire assembly can be significantly reduced while still providing the necessary cooling for safe and efficient operation.

SUMMARY

Accordingly, it is an object of the present invention to provide an improvement in high frequency phased array radar systems.

It is another object of the invention to provide an architecture for an active electronically scanned phased array radar system operating in the Ka-band of frequencies above 30 GHz.

It is yet another object of the invention to provide an active electronically scanned phased array Ka-band radar system having a multi-function capability for use with both ground and air vehicles.

These and other objects are achieved by an architecture for a Ka-band multi-function radar system (KAMS) comprised of multiple parallel layers of electronics circuitry and waveguide components which are stacked together so as to form a unitary structure behind an antenna faceplate. The invention includes the concepts of vertical integration and solderless interconnects of active electronic circuits while maintaining the required array grid spacing for Ka-band operation and comprises, among other things, a transitioning RF waveguide relocator panel located behind a radiator faceplate and an array of beam control tiles respectively coupled to one of a plurality of transceiver modules via an RF manifold. Each of the beam control tiles includes respective high power transmit/receive (T/R) cells as well as RF stripline and coaxial transmission line elements. In the preferred embodiment of the invention, the waveguide relocator panel is comprised of a diffusion bonded copper laminate stack up with dielectric filling while the beam control tiles are fabricated by the use of multiple layers of low temperature co-fired ceramic (LTCC) material laminated together and designed to route RF signals to and from a respective transceiver module of four transceiver modules and a quadrature array of antenna radiators matched to free space formed in the faceplate. Planar type metal spring gaskets are provided between the interfacing layers so as to prevent RF leakage from around the perimeter of the waveguide ports of abutting layer members. Cooling of the various components is achieved by a pair of planar forced air heat sink members which are located on either side of the array of beam control tiles. DC power and control of the T/R cells is provided by a printed circuit wiring board assembly located adjacent to the array of beam controlled tiles with solderless DC connections being provided by an arrangement of “fuzz button” electrical connector elements. Alignments pins are provided at different levels of the planar layers to ensure that waveguide, electrical signals and power interface properly.

Further scope of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood, however, that the detailed description and specific example while indicating the preferred embodiment of the invention, it is provided by way of illustration only since various changes and modifications coming within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the various drawing figures wherein like reference numerals refer to like components throughout, reference is first made toFIG. 1wherein there is shown an electrical block diagram broadly illustrative of the subject invention and which is directed to a Ka-band multi-function system (KAMS) active bidirectional electronically scanned antenna (AESA) array utilized for both transmitting and receiving RF signals to and from a target.

InFIG. 1, reference numeral30denotes a transceiver module sub-assembly comprised of four transceiver modules321. . .324, each including an input terminal34for RF signals to be transmitted, a local oscillator input terminal36and a receive IF output terminal38. Each transceiver module, for example module321, also includes a frequency doubler40, transmit RF amplifier circuitry42, and a transmit/receive (T/R) switch44. Also included is receive RF amplifier circuitry46coupled to the T/R switch44. The receive amplifier46is coupled to a second harmonic (X2) signal mixer48which is also coupled to a local oscillator input terminal36. The output of the mixer48is connected to an IF amplifier circuit50, whose output is coupled to the IF output terminal38. The transmit RF signal applied to the input terminal34and the local oscillator input signal applied to the terminal36is generated externally of the system and the IF output signal is also utilized by well known external circuitry, not shown.

The four transceiver modules321. . .324of the transceiver module section30are coupled to an RF manifold sub-assembly52consisting of four manifold sections541. . .544, each comprised of a single port56coupled to a T/R switch44of a respective transceiver module32and four RF signal ports581. . .584which are respectively coupled to one beam control tile60of a set62of sixteen identical beam control tiles601. . .6016arranged in a rectangular array, shown inFIG. 2.

Each of the beam control tiles601. . .6016implements sixteen RF signal channels641. . .6416so as to provide an off-grid cluster of two hundred fifty-six waveguides661. . .66256which are fed to a grid of two hundred fifty-six radiator elements671. . .67256in the form of angulated slots matched to free space in a radiator faceplate68via sixteen waveguide relocator sub-panel sections701. . .7016of a waveguide relocator panel69shown inFIGS. 7A and 7B. The relocator panel69relocates the two hundred fifty six waveguides661. . .66256in the beam control tiles641. . .6416back on grid at the faceplate68and which operate as a quadrature array with the four transceiver modules321. . .324.

The architecture of the AESA system shown inFIG. 1is further illustrated inFIG. 2and comprises an exploded view of the multiple layers of planar components that are stacked together in a vertically integrated assembly with metal spring gasket members being sandwiched between interfacing layers or panels of components to ensure the electrical RF integrity of the waveguides661. . .66256through the assembly. In addition to the transceiver section30, the manifold section52, the beam control tile array62, the waveguide relocator panel69, and the faceplate68referred to inFIG. 1, the embodiment of the invention includes a first spring gasket member72fabricated from beryllium copper (Be—Cu) located between the antenna faceplate68and the waveguide relocator panel69, a second Be—Cu spring gasket member74located between the waveguide relocator panel69and an outer heat sink member76, a third set of Be—Cu spring gasket members781. . .785which are sandwiched between the array62of beam control tiles601. . .6016, and a fourth set of four Be—Cu spring gasket members821. . .824which are located beneath the beam control tile array62and a DC printed wiring board84which includes an assembly of DC fuzz button connector boards80mounted thereon. Beneath the printed wiring board84is an inner heat sink86and the RF manifold section52referred to above and which is followed by the transceiver module assembly30which is shown inFIG. 2including one transceiver module321, of four modules321. . .324shown inFIG. 1. When desirable, however, the antenna faceplate, the relocator panel, and outer heat could be fabricated as a single composite structure.

The relative positions of the various components shown inFIG. 2are further illustrated in block diagrammatic form inFIG. 3. In the diagram ofFIG. 3, the fuzz button boards80and the fourth set of spring gasket members82are shown in a common block because they are placed in a coplanar sub-assembly between the array62of beam control tiles601. . .604and the inner heat sink86. The inner heat sink86and the RF manifold52are shown in a common block ofFIG. 3because they are comprised of members which, as will be shown, are bonded together so as to form a composite mechanical sub-assembly.

Referring now to the details of the various components shown inFIG. 2, FIGS.4and5A–5C are illustrative of the antenna faceplate68which consists of an aluminum alloy plate member88and which is machined to include a grid of two hundred fifty six radiator elements671. . .67256which are matched to free space and comprise oblong slots having rounded end portions. As shown inFIGS. 5A and 5B, each radiator slot67includes an impedance matching step90in the width of the outer end portion92. The outer surface94of the aluminum plate88includes a layer of foam material96which is covered by a layer of dielectric98that provides wide angle impedance matching (WAIM) to free space.

Dielectric adhesive layers95and99are used to bond the foam material96to the plate88and WAIM layer98. Reference numerals100and102inFIG. 4refer to a set of mounting and alignment holes located around the periphery of the grid of radiator elements671. . .67256.

Referring now toFIG. 6, located immediately below and in contact with the antenna faceplate68is the first Be—Cu spring gasket member72which is shown having a grid104of two hundred fifty six elongated oblong openings1061. . .106256which are mutually angulated and match the size and shape of the radiator elements671. . .67256formed in the faceplate68. The spring gasket72also includes a set of mounting holes108and alignment holes110formed adjacent the outer edges of the openings which mate with the mounting holes100and alignment holes102in the faceplate68.

Immediately adjacent the first spring gasket member72is the waveguide relocator panel69shown inFIGS. 7A and 7B69comprised of sixteen waveguide relocator sub-panel sections701. . .7016, one of which is shown inFIG. 7C.FIG. 7Adepicts the front face of the relocator panel69whileFIG. 7Bdepicts the rear face thereof.

The relocator panel69is preferably comprised of multiple layers of diffusion bonded copper laminates with dielectric filling. However, when desired, multiple layers of low temperature co-fired ceramic (LTCC) material or high temperature co-fired ceramic (HTCC) or other suitable ceramic material could be used when desired, based upon the frequency range of the tile application.

As shown inFIG. 7C, each relocator sub-panel section70includes a rectangular grid of sixteen waveguide ports1121. . .11216slanted at 45° and located in an outer surface114. The waveguide ports1121. . .11216are in alignment with a corresponding number of radiator elements67in the faceplate68and matching openings1061. . .106256in the spring gasket72(FIG. 6).

The waveguide ports1121. . .11216transition to two linear mutually offset sets of eight waveguide ports1161. . .1168and1169. . .11616, shown inFIGS. 8A–8C, located on an inner surface118. The waveguide ports1161. . .1168and1169. . .11616couple to two like linear mutually offset sets of eight waveguide ports1221. . .1228and1229. . .12216on the outer edge surface portions124and126of the beam control tiles601. . .6016, one of which is shown inFIG. 13. Such an arrangement allows room for sixteen transmit/receive (T/R) cells, to be described hereinafter, to be located in the center recessed portion128of each of the beam control tiles601. . .6016. The relocator sub-panel sections701. . .7016of the waveguide relocator panel69thus operate to realign the ports1221. . .12216of the beam control tiles601. . .6016from the side thereof back on to the grid104of the spring gasket72(FIG. 6) and the radiator elements67in the faceplate68.

As further shown inFIGS. 8A–8C, each relocator sub-panel section70includes two sets of eight waveguide transitions1301. . .1308and1321. . .1328formed therein by successive incremental angular rotation, e.g., 45°/25=1.8° of the various rectangular waveguide segments formed in the panel layers. The transitions130comprise vertical transitions, while the transitions132comprise both vertical and lateral transitions. As shown, the vertical and lateral transitions1301. . .1308and1321. . .1328terminate in the mutually parallel ports1121. . .11216matching the openings106in the spring gasket72shown inFIG. 6as well as the radiator elements67in the faceplate68.

Referring now toFIG. 9, shown thereat is the second Be—Cu spring gasket member74which is located between the inner face of the waveguide relocator panels69shown inFIG. 7Band the outer surface of the outer heat sink member76shown inFIG. 10. The spring gasket74includes five sets1361. . .1365of rectangular openings138which are arranged to mate with the ports1161. . .11616of the relocator sub-panel sections701. . .7016. The five sets1361. . .1365of openings138are adapted to also match five like sets1401. . .1405of waveguide ports142in the outer surface134of the outer heat sink76and which form portions of five sets of RF dielectric filled waveguides, not shown, formed in the raised elongated parallel heat sink body portions1441. . .1445.

Referring now toFIG. 11, shown thereat is a third set of five discrete Be—Cu spring gasket members781,782. . .785which are mounted on the back surface146of the outer heat sink76as shown inFIG. 12and include rectangular opening148which match the arrangement of openings138in the second spring gasket74shown inFIG. 9as well as the waveguide ports143in the heat sink76and the dielectric filled waveguides, not shown, which extend through the body portions1441. . .1445to the inner surface146as shown inFIG. 12.FIG. 12also shows for sake of illustration one beam control tile60(FIG. 13) located on the inner surface146of the outer heat sink76against the spring gasket members784and785. It is to be noted, however, that sixteen identical beam control tiles601. . .6016as shown inFIG. 13are actually assembled side by side in a rectangular array on the back surface of the heat sink76.

Considering now the construction of the beam control tiles601. . .6016, one of which is shown in perspective view inFIG. 13by reference numeral60, it is preferably fabricated from multiple layers of LTCC material. When desired however, high temperature co-fired ceramic (HTCC) material could be used. As noted above, each beam control tile60of the tiles601. . .6016includes sixteen waveguide ports1221. . .12216and associated dielectric waveguides1231. . .12316arranged in two offset sets of eight waveguide ports1221. . .1228and1229. . .12216mutually supported on the outer surface portions124and126of an outermost layer150.

Referring now toFIG. 14A, shown thereat is a top plan view of the beam control tile60shown inFIG. 13. Under the centralized generally rectangular recessed cavity region128is located sixteen T/R chips1661. . .16616, fabricated in gallium arsenide (GaAs), located on an underlying layer152of the beam control tile60as shown inFIG. 14B. The layer150shown inFIG. 14Aincluding the outer surface portions also includes metallic vias170which pass through the various LTCC layers so as to form RF via walls on either side of two sets of buried stripline transmission lines1741. . .1748and1749. . .17416located on layer152(FIG. 14B). Vias are elements of conductor material which are well known in the art and comprise metallic pathways between one or more layers of dielectric material, such as, but not limited to, layers of LTCC or HTCC material. The walls of the vias170ensure that RF signals do not leak from one adjacent channel to another. Also, shown in an arrangement of vias172which form two sets of the eight RF waveguides1231. . .1238, and1239. . .12316shown inFIG. 13. Two separated layers of metallization178and180are formed on the outer surface portions124and126overlaying the vias170and172and act as shield layers.

InFIG. 14B, four coaxial transmission line elements1861. . .1864including outer conductor1841. . .1844and center conductors1881. . .1884are shown in central portion of the cavity region128. The center conductors1881. . .1884are connected to four RF signal dividers1901. . .1904which may be, for example, well known Wilkinson signal dividers which couple RF signals between the T/R chips1661. . .16616and the coaxial transmission lines1861. . .1864. DC control signals are routed within the beam control tile60and surface in the cavity region128and are bonded to the T/R chips with gold bond wires192as shown. Also shown inFIG. 14Bare four alignment pins1961. . .1964located at or near the corners of the tile60.

Referring now toFIG. 14C, shown thereat is a tile layer198below layer152(FIG. 14B). Layer198contains the configuration of vias172that are used to form walls of waveguides1231. . .1234. In addition, a plurality of vias202are placed close together to form a slot in the dielectric layer so as to ensure that a good ground is presented for the T/R chips1661. . .16616shown inFIG. 14Bat the point where RF signals are coupled between the T/R chips1661. . .16616and the waveguides1231. . .1234to the respective chips. Another set of via slots204are included in the outer conductor portions1841. . .1844of the coaxial transmission line elements1861. . .1864to produce a capacitive matching element so as to provide a match to the bond wires connecting the RF signal dividers1901. . .1904to the inner conductor elements1881. . .1884as shown inFIG. 14B. Also, there is provided a set of vias206for providing grounded separation elements between the overlying T/R chips1661. . .16616.

Turning attention now toFIG. 14D, shown thereat is a buried ground layer208which includes a metallized ground plane layer210of metallization for walls of the waveguides1231. . .1234, the underside of the active T/R chips1661. . .16616as well as the coaxial transmission line elements1861. . .1864, Also provided on the layer208is an arrangement of DC connector points211for the various components in the T/R chips1661. . .16616. Portions of the center conductors1881. . .1884and the outer conductors1841. . .1844for the coaxial transmission line elements1861. . .1864are also formed on layer208.

Beneath the ground plane layer208is a signal routing layer214shown inFIG. 14Ewhich also includes the vertical vias172for the sixteen waveguides1231. . .1234. Also shown are vias of the inner and outer conductors1881. . .1884and1841. . .1844of the four coaxial transmission lines1861. . .1864, Also located on layer214is a pattern219of stripline members for routing DC control and bias signals to their proper locations.

Below layer214is dielectric layer220shown inFIG. 14Fwhich is comprised of sixteen rectangular formations2221. . .22216of metallization further defining the side walls of the waveguides1761. . .17616along with the vias172shown inFIGS. 14A,14C and14E. Four rings of metallization are shown which further define the outer conductors1841. . .1844of the coaxial lines1861. . .1864along with vias forming the center conductors1881. . .1884. Also shown are patterns226of metallization used for routing DC signals to their proper locations.

Referring now toFIG. 14G, shown thereat is a dielectric layer230which includes a top side ground plane layer232of metallization for three RF branch line couplers shown in the adjacent lower dielectric layer236shown inFIG. 14Hby reference numerals2341,2342,2343. The layer of metallization232also includes a rectangular portion of metallization237for defining the waveguide walls of a single waveguide238on the back side of the beam control tile60for routing RF between one of the four transceiver modules321. . .324(FIG. 2) and the sixteen waveguides1231. . .1234, shown, for example, inFIGS. 14A–14F.FIG. 14Galso includes a pattern240of metallization for providing tracks for DC control of bias signals in the tile60. Also, shown inFIG. 14Gare metallizations for the vias of the four center conductors1881. . .1884of the four coaxial transmission line elements1861. . .1864.

With respect toFIG. 14H, shown thereat are the three branch couplers2341,2342and2343, referred to above. These couplers operate to connect an RF via waveguide probe242within the backside waveguide238to four RF feed elements2441. . .2444which vertically route RF to the four RF coaxial transmission lines1861. . .1864in the tile structure shown inFIGS. 14D–14G. The three branch line couplers2341,2342,2343are also connected to respective dagger type resistive load members2461,2462and2463shown in further detail inFIG. 18. All of these elements are bordered by a fence of metallization248. As in the metallization ofFIG. 14G, the right hand side of the layer14H also includes a set of metal metallization tracks250for DC control and bias signals.

FIG. 14Ishows an underlying via layer252including a pattern254of buried vias255which are used to further implement the fence248shown inFIG. 14Ialong with vias for the center conductors1881. . .1884of the coaxial lines1861. . .1864. The dielectric layer252also includes three parallel columns of vias256which interconnect with the metallization patterns240and250shown inFIGS. 14G and 14H.

The back side or lowermost dielectric layer of the beam control tile60is shown inFIG. 14Jby reference numeral258and includes a ground plane260of metallization having a rectangular opening defining a port262for the backside waveguide238. A grid array262of circular metal pads264are located to one side of layer258and are adapted to mate with a “fuzz button” connector element on a board80shown inFIG. 2so as to provide a solderless interconnection means for electrical components in the tile60. Also located on the bottom layer258are four control chips2661. . .2664which are used to control the T/R chips1661. . .16616shown inFIG. 14B.

Having considered the various dielectric layers in the beam control tile60, reference is now made toFIG. 15where there is shown a layout of one transmit/receive (T/R) chip166of the sixteen T/R chips1661. . .16616which are fabricated in gallium arsenide (GaAs) semiconductor material and are located on dielectric layer182shown inFIG. 14C. As shown, reference numeral268denotes a contact pad of metallization on the left side of the chip which connects to a respective signal divider190of the four signal dividers1901. . .1904shown inFIG. 14C. The contact pad268is connected to a three-bit RF signal phase shifter270implemented with microstrip circuitry including three phase shift segments2721,2722and2723. Control of the phase shifter270is provided DC control signals coupled to four DC control pads2741. . .2744. The phase shifter270is connected to a first T/R switch276implemented in microstrip and is coupled to two DC control pads2781and2782for receiving DC control signals thereat for switching between transmit (Tx) and receive (Rx) modes. The T/R switch276is connected to a three stage transmit (Tx) amplifier280and a three stage receive (Rx) amplifier282, respectively implemented with the microstrip circuit elements and P type HEMT field effect transistors2841. . .2843and2861. . .2863. A pair of control voltage pads2881and2882are utilized to supply gate and drain power supply voltages to the transmit (Tx) amplifier280, while a pair of contact pads2901and2902supply gate and drain voltages to semiconductor devices in the RF receive (Rx) amplifier282. A second T/R switch292is connected to both the Tx and Rx RF amplifiers280and282, which in turn is connected via contact pad294to one of the sixteen transmission lines1741. . .17416shown inFIG. 14Cwhich route RF signals to and from the waveguides1761. . .17616.

FIGS. 16,17A and17B are illustrative of the microstrip and stripline transmission line components forming the transition from a T/R chip166in a beam control tile60to the waveguide probe175at the tip of transmission line element174in one of the waveguides123of the sixteen waveguides1231. . .1234(FIG. 14B). Reference numeral125denotes a back short for the waveguide member123As shown, the transition includes a length of microstrip transmission line296formed on the T/R chip166which connects to a microstrip track section298via a gold bond wire300in an air portion302of the beam control tile60where it then passes between a pair of adjoining layers304and306of LTCC ceramic material including an impedance matching segment173where it connects to the waveguide probe175shown inFIG. 17A. As shown inFIGS. 16 and 17A, the waveguide123is coupled upwardly to the antenna faceplate68through the relocator panel69.

Considering brieflyFIG. 18, it discloses the details of one of the dagger load elements246of the three dagger loads2461,2462and2463shown inFIG. 14Hconnected to one leg of the branch line couplers2341,2342, and2343. The dagger load element246consists of a tapered segment308of resistive material embedded in multilayer LTCC material310. The narrow end of the resistor element308connects to a respective branch line coupler234of the three branch line couplers2341,2342, and2343shown inFIG. 14Hvia a length of stripline material312.

Referring now toFIGS. 19A and 19B, shown thereat are the details of the manner in which the coaxial RF transmission lines1861. . .1864, shown for example inFIGS. 14B–14G, are implemented through the various dielectric layers so as to couple arms2451. . .2454of the branch line couplers2341. . .2343ofFIG. 14Hto the signal dividers1901. . .1904shown inFIG. 14B. As shown, a stripline connection314is made to a signal divider190via multiple layers316of LTCC material in which are formed arcuate center conductors188and the outer conductors184of a coaxial waveguide member186and terminating in the stripline245of a branch line coupler234so that the upper and lower extremities are offset from each other. Reference numeral204denotes the capacitive matching element shown inFIG. 14C.

Considering now the remainder of the planar components of the embodiment of the invention shown inFIG. 2,FIG. 20, for example, discloses the underside surface146of the outer heat sink member76, previously shown inFIG. 12. However,FIG. 20now depicts sixteen beam control tiles601,602, . . .6016mounted thereon, being further illustrative of the array62of control tiles shown inFIG. 2. Beneath the beam control tiles601. . .6016are the five spring gasket members781. . .785shown inFIG. 11.FIG. 20now additionally shows a set of four fuzz button connector boards801,802, . . .804in place against sets of four beam control tiles601. . .6016of the array62.

FIG. 21further shows the DC printed wiring board84covering the fuzz button boards801. . .804shown inFIG. 20.FIG. 21additionally shows a pair of dual in-line pin connectors851and852.FIG. 22is illustrative of the underside of the DC wiring board84with the four fuzz button boards801,802,803, and804shown inFIG. 20.

Referring now toFIG. 23, shown thereat is the set of fourth BeCu spring gasket members821,822,823, and824which are mounted coplanar and parallel with the fuzz button boards801,802,803and804shown inFIG. 20. Each of gasket members821. . .824include four rectangular openings831. . .834which are aligned with the four sets of rectangular openings871,872,873, in the DC wiring board84. A cross section of the sub-assembly of the components shown inFIGS. 21–23is shown inFIG. 24.

Mounted on the underside of the DC wiring board84is the inner heat sink member86which is shown inFIG. 25together with the RF manifold52which is bonded thereto so as to form a unitary structure. The inner heat sink member86comprises a generally rectangular body member fabricated from aluminum and includes a cavity88with four cross ventilating air cooled channels871.872,873and874formed therein for cooling an array of sixteen outwardly facing dielectric waveguide to air waveguide transitions891. . .8916as well as DC chips and components mounted on the wiring board84which are also shown inFIG. 26which couple to the waveguides238(FIG. 14K) of the wave control tiles601. . .6016.

The details of one of the transitions89is shown inFIGS. 27A and 27B. The transitions89as shown include a dielectric waveguide to air waveguide RF input portion91which faces outwardly from the cavity88as shown inFIG. 25and is comprised of a plurality of stepped air waveguide matching sections93up to an elongated relatively narrow RF output portion95including an output port97. Output ports971. . .9716for the sixteen transition891. . .8916are shown inFIG. 26and which couple to a respective backside dielectric waveguide238such as shown inFIG. 14Kthrough spring gasket members82of the sixteen beam control tiles601. . .6016. Reference numerals238and242shown inFIGS. 27A and 27Brespectively represent the waveguides and the stripline probes shown inFIG. 14I.

Considering now the RF manifold section52referred to inFIG. 1, the details thereof are shown inFIGS. 25 and 28. The manifold52coincides in size with the inner heat sink member86and includes a generally rectangular body portion51formed of aluminum and which is machined to include two channels531and532formed in the underside thereof so as to pass air across the body portion51so as to provide cooling. As shown, the manifold member52includes four magic tee waveguide couplers541. . .544, each having four arms571. . .574as shown inFIG. 28coupled to RF signal ports561. . .564and which are fabricated in the top surface63so as to face the inner heat sink52as shown inFIG. 25. The RF signal ports561. . .564of the magic tee couplers541. . .544respectively couple to an RF input/output port35shown inFIG. 29of a transceiver module32which comprises one of four transceiver modules321. . .324shown schematically inFIG. 1.

The transceiver module32shown inFIG. 29is also shown including terminals34,36and38, which couple to transmit, local oscillator and IF outputs shown inFIG. 1. Also, each transceiver module32includes a dual in-line pin DC connector37for the coupling of DC control signals thereto.

Accordingly, the antenna structure of the subject invention employs a planar forced air heat sink system including outer and inner heat sinks76and86which are embedded between electronic layers to dissipate heat generated by the heat sources included in the T/R cells, DC electrical components and the transceiver modules. Alternatively, the air channels531,532, and871,872,873, and874included in the inner heat sink86and the waveguide manifold52could be filled with a thermally conductive filling to increase heat dissipation or could employ liquid cooling, if desired.

Having thus shown what is considered to be the preferred embodiment of the invention, it should be noted that the invention thus described may be varied in many ways. Such variations are not regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.