Abstract:
A radio frequency transmitting and receiving module having a support housing that has a hexagonal face member mounted to the support housing. This face member has an antenna for transmitting and receiving radio frequency signals. Mounted within the support housing is circuitry for (a) conducting radio frequency signals to the antenna for transmission by the antenna, and (b) conducting radio frequency signals received by the antenna from the antenna for processing. Such a module, functioning as a hexagonal power unit core, can be fixed in a honeycomb cellular array employing “plug and play” assembly techniques.

Description:
FIELD OF THE INVENTION 
     The present invention relates, in general, to radio frequency transmitters and receivers and, in particular, to fully integrated modules that include an antenna and the networks for transmitting and receiving radio frequency signals over a broad frequency range as stand-alone systems or as modular components of linear, planar and application-specific phased arrays. 
     BACKGROUND OF THE INVENTION 
     Advances in the development of monolithic microwave integrated circuits (MMIC) combined with the application of multi-layer low temperature cofired ceramic (LTCC) technology has reduced dramatically the size of radio frequency networks, including the generation of solid state transmitter power. This, in turn, allows for a high level of integration and miniaturization of both the transmitting/receiving radio frequency paths and the ancillary control networks that can now be brought forward and integrated with the radiating aperture. 
     Among the benefits derived from such arrangements are (a) improved efficiency and lower power dissipation in the radio frequency paths, (b) decreased requirements on the power supply, (c) improved system reliability, (d) elimination of multiple housings and cumbersome interconnects, and (e) more flexible, conformal installations, particularly on space-limited platforms. 
     SUMMARY OF THE INVENTION 
     A radio frequency transmitting and receiving module, constructed in accordance with the present invention, includes a support housing and a hexagonal face member mounted to the support housing and having an antenna for transmitting and receiving radio frequency signals. Also included in this module is circuitry within and mounted to the support housing for conducting radio frequency signals to the antenna for transmission by the antenna and conducting radio frequency signals received by the antenna from the antenna for processing. 
     According to a second aspect of the present invention, radio frequency transmitting and receiving module includes a support housing having a first end plate, a second end plate, and means for securing together the first end plate and the second end plate. This module also has an antenna mounted to the first end plate for transmitting and receiving radio frequency signals and circuitry that includes a transmit/receive module on a first substrate and control electronics and power conditioning networks on a second substrate. The first and second substrates are within the housing and sandwiched between the first end plate and the second end plate. The circuitry conducts radio frequency signals to the antenna for transmission by the antenna and conducts radio frequency signals received by the antenna from the antenna for processing. 
     According to another aspect of the present invention, a radio frequency transmitting and receiving module, constructed in accordance with the present invention, is used in an array of such modules that are fixed in a desired pattern. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a first embodiment of a radio frequency transmitting and receiving module constructed in accordance with the present invention. 
         FIG. 2  is an exploded perspective view of the  FIG. 1  radio frequency transmitting and receiving module. 
         FIG. 3  is a perspective view, taken from the rear, of the  FIG. 1  radio frequency transmitting and receiving module. 
         FIG. 4  is a perspective view of a second embodiment of a radio frequency transmitting and receiving module constructed in accordance with the present invention. 
         FIG. 5  is an exploded perspective view of the  FIG. 4  radio frequency transmitting and receiving module. 
         FIG. 6  is a perspective view of an array of radio frequency transmitting and receiving modules constructed in accordance with the present invention. 
         FIG. 7  is a perspective view of parts of two  FIG. 1  radio frequency transmitting and receiving modules prior to being attached together in an array. 
         FIG. 8  is a perspective view of two  FIG. 1  radio frequency transmitting and receiving modules after being attached together in an array. 
         FIG. 9  is a block diagram of a preferred embodiment of the system architecture of a radio frequency transmitting and receiving module constructed in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1 ,  2 , and  3 , a radio frequency transmitting and receiving module  20 , constructed in accordance with the present invention, includes a support housing. For the embodiment of the invention being described, the support housing includes a hexagonal first end plate  22  at a first end of the support housing and a hexagonal second plate  24  at a second end of the support housing. Hexagonal end plates  22  and  24  are shown aligned. These end plates are secured together by suitable means, such as a plurality of screws (not shown), that pass through second end plate  24  and are received in fingers  22   a  of first end plate  22 . 
     A cowling  26 , also hexagonal, extends around the peripheral edges of first end plate  22  and second end plate  24 . As shown most clearly in  FIG. 2 , cowling  26  is composed of two parts  26   a  and  26   b  that are attached to first end plate  22  and second end plate  24  by suitable means, such as a plurality of screws, disposed at locations that secure the cowling parts to the end plates. 
     A radio frequency transmitting and receiving module, constructed in accordance with the present invention, further includes a hexagonal face member  28  mounted to the support housing. For the embodiment of the invention being described, hexagonal face member  28  is mounted to first end plate  22  of the support housing. 
     Hexagonal face member  28  has an antenna  30  for transmitting and receiving radio frequency signals. Antenna  30  preferably is a high-power, reflective-cavity backed spiral antenna composed of first and second interlaced spiral windings  30   a  and  30   b.    
     Various configurations of antenna  30  can be used. For the two interlaced spiral winding configuration illustrated in  FIGS. 1 and 2 , spiral windings  30   a  and  30   b  are Archimedean progressions that unfurl from a pair of radio frequency input terminals  32   a  and  32   b , respectively, with the final turn of each end portion of each spiral winding including a logarithmic progression. The final turn of the first spiral winding slowly widens to a maximum width and then slowly tapers to a minimum width at an end point. Other spiral configurations, such as sinuous, four square or multi-arm configurations can be used. 
     A radio frequency transmitting and receiving module, constructed in accordance with the present invention, also includes circuitry within and mounted to the support housing for conducting radio frequency signals to antenna  30  for transmission by the antenna and conducting radio frequency signals received by the antenna from the antenna for processing. This circuitry includes a transmit/receive module on a first substrate  33  and control electronics and power conditioning networks on a second substrate  34 . 
     First end plate  22  has a passage  36  for a radio frequency antenna launch  38  that is on first substrate  33  and treated as part of the transmit/receive module on first substrate  33 . Second end plate  24  serves as an external interface plate for a connector  40  to provide input radio frequency and connectors  42  and  44  to provide input control and DC power. Antenna launch  38  can be a twin-wire transmission line, including parallel conductors, that extend through first end plate  22  and are connected to radio frequency input terminals  32   a  and  32   b  of spiral windings  30   a  and  30   b , respectively. 
     A radio frequency transmitting and receiving module, constructed in accordance with the present invention, preferably includes a cooling fan  46  mounted to the support housing. As shown most clearly in  FIG. 3 , cooling fan  46  is mounted on second end plate  24  of the support housing. First end plate  22  of the support housing is perforated for cooling radio frequency transmitting and receiving module  20 . 
     In summary, the structure of the radio frequency transmitting and receiving module  20  described above includes a support housing having a first end plate  22 , a second end plate  24 , and a cowling  26 . Circuitry that includes a transmit/receive module on a first substrate  33  and control electronics and power conditioning networks on a second substrate  34  is sandwiched between the first end plate and the second end plate of the support housing and the cowling of the support housing envelopes the first end plate and the second end plate of the support housing, the circuitry, and cooling fan  46 . 
     The specific construction of a radio frequency transmitting and receiving module, constructed in accordance with the present invention, is dependent on the operating frequency of the module. At frequencies beyond the high frequency region, the radiating aperture  36  is significantly smaller than at lower frequencies and certain of the components, located within and supported by the support housing, are disposed differently. 
       FIGS. 4 and 5  illustrate a second embodiment of a radio frequency transmitting and receiving module  47  constructed in accordance with the present invention. The radio frequency transmitting and receiving module illustrated by  FIGS. 4 and 5  operates at frequencies higher that the one illustrated by  FIGS. 1 ,  2 , and  3 . The second embodiment of the present invention, while generally similar to the first embodiment illustrated, differs from the first embodiment in two respects. First, substrate  33 , that carries the transmit/receive module, and substrate  34 , that carries the control electronics and power conditioning networks, are disposed parallel to the axis of the radio frequency transmitting and receiving module rather than transverse to the axis of the radio frequency transmitting and receiving module as with the first embodiment. Second, the embodiment of  FIGS. 4 and 5  includes a pair of heat sinks  48  and  50 , attached, respectively, to substrate  33  that carries the transmit/receive module and to substrate  34  that carries the control electronics and power conditioning networks. 
     In all other respects, the radio frequency transmitting and receiving module  47  of  FIGS. 4 and 5  is similar to the radio frequency transmitting and receiving module  20   FIGS. 1 ,  2 , and  3 . The radio frequency transmitting and receiving module  47  of  FIGS. 4 and 5  includes a support housing having a first end plate  22 , a second end plate  24 , and a two-part cowling  26   a  and  26   b . Circuitry that includes a transmit/receive module on a first substrate  33  and control electronics and power conditioning networks on a second substrate  34  heat sinks  48  and  50  are sandwiched between the first end plate and the second end plate of the support housing and the cowling of the support housing envelopes the first end plate and the second end plate of the support housing, the circuitry, the heat sinks and a cooling fan. The end plates are secured together by suitable means, such as a plurality of screws (not shown), that pass through second end plate  24  and are received in fingers  22   a  of first end plate  22 . A hexagonal face member  28 , having an antenna  30 , is mounted to first end plate  22  of the support housing. 
       FIG. 6  is a perspective view of an array of radio frequency transmitting and receiving modules  60  constructed in accordance with the present invention. Modules  60  are fixed in a desired pattern by means that are illustrated in  FIGS. 1 through 4 ,  7  and  8 . 
     Referring to  FIGS. 1 through 4 ,  7  and  8 , second end plate  24  of a first module  62  has a first pair of rear mounting claws  64  on a first hexagonal edge and second pair of rear mounting claws  66  on a second hexagonal edge adjacent the first hexagonal edge. A second end plate  24  of a second module  68  has a pair of rear mounting pockets  70  on a hexagonal edge within which the first pair of rear mounting claws  64  are received. The second end plate of a third module (not shown) has a pair of rear mounting pockets on a hexagonal edge within which the second pair of rear mounting claws  66  are received. 
     First end plate  22  of module  62  (module  20  in  FIG. 1 ) has a first forward mounting claw  72  on a first hexagonal edge and a second forward mounting claw  74  on a second hexagonal edge adjacent the first hexagonal edge. A first end plate  22  of second module  68  has a forward mounting pocket  75  on a hexagonal edge within which first forward mounting claw  72  is received. The first end plate of the third module (not shown) has a forward mounting pocket on a hexagonal edge within which second forward mounting claw  74  is received. 
     The radio frequency transmitting and receiving modules  60  are arranged in an array by first aligning the proper mating surfaces of the modules so that they touch each other. Next, a jackscrew  76 , accessible at the second end plate as shown in  FIG. 3 , is advanced to raise and associated forward mounting claw into the forward mounting pocket of the mating radio frequency transmitting and receiving module with which the forward mounting claw is aligned. Then set screws  77  on the rear mounting claws, shown most clearly in  FIG. 3 , are loosened and the associated rear mounting claws are pivoted 90° into the rear mounting pockets in the adjacent radio frequency transmitting and receiving module with which the rear mounting claws are aligned. In the final step, the set screws  77  on the rear mounting claws are tightened, thereby providing mating tension with the forward mounting claw that has been received in the associated forward mounting pocket in the mating radio frequency transmitting and receiving module. 
     Once a given radio frequency transmitting and receiving module is given the position coordinates of its location in an array with respect to a reference module, an internal microprocessor translates the position for setting a true time delay network in execution of array beam steering. If simultaneous multiple beams are required, the microprocessor will account for array aperture segmentation. These functions can be exercised in both the transmit mode and the receive mode as required by the specific application. 
       FIG. 9  is a block diagram of a preferred embodiment of the system architecture of a radio frequency transmitting and receiving module constructed in accordance with the present invention. At the initial deployment of the radio frequency transmitting and receiving module, a microprocessor  80  determines whether the unit is operating as a stand-alone module or as part of a phased array. For stand-alone operation, a true time delay network  82  is by-passed. Channel selectors  84  are latched for either transmission or reception. In transmission, power amplifiers  86  are activated and respond appropriately to input radio frequency pulses and modulations. 
     There are two parallel channels  88  and  90  in this portion of the radio frequency path allowing for doubling the output power of a given radio frequency transmitting and receiving module. This results in practical advantages. First, each of the output transmitters  91  operates at a reduced power level, thus increasing the system reliability. Second, the heat generated within each radio frequency transmitting and receiving module is distributed for more efficient cooling. 
     The output from transmitters is fed to the radiating element (not shown in  FIG. 9 ). Because the radiating elements in the two embodiments of the invention being described are interlaced spiral windings, the relative phase of the two feeds are at 180°, an operating feature well-known in the art. For this purpose, a fixed 180° phase bit  92  is included in one of the radio frequency paths. In receive mode, the radio frequency progression is reversed via the channel selectors  84  and the received signal is available at the radio frequency port for system processing and analysis. 
     A significant feature of the dual transmit/receive paths in the system architecture is the capability of replacing the interlaced spiral windings antenna with a dual polarized antenna, such as a log periodic or sinuous antenna, and providing a polarization-diverse antenna module. 
     When the radio frequency transmitting and receiving module is deployed in a phased array, the array control electronics provides the beam steering commands to the true time delay network  82  both in transmission and reception. Receivers  94  within the module are combined at the input to true time delay network  82  and proceed via the radio frequency path to the array processor. 
     Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.