Integrated antenna-converter system in a unitary package

Abstract: Monolithic microwave integrated circuit (MMIC) technology is advantageously used to fabricate microwave circuitry for an antenna-converter system to enable an antenna (102) and its associated converter circuits (109) to be integrated together into a unitary package (100). Small reliable radio frequency (RF) circuits, polarization switch matrix circuits, intermediate frequency (IF) circuits and power and control circuits for the converter are manufactured and integrated onto a plurality of small area microwave circuit disks (120-121) using MIC/MMIC technology. The plurality of converter circuit disks are sandwiched together and directly mounted flat against the back of the antenna to form a unitary package. The disks for the converter circuits are further sized such that the circuit disks fit within an envelope volume defined by the size and shape of the antenna.

Description: TECHNICAL FIELD The present invention relates to the packaging of antennas and associated converter circuits and, in particular, to an integrated antenna-converter system implemented in a unitary package by fabricating the converter circuits using microwave integrated circuit and monolithic microwave integrated circuit technologies on a plurality of substrates mounted directly to the back of the antenna. BACKGROUND OF THE INVENTION Conventionally, an antenna and the various components of its associated converter circuitry (such as radio frequency receivers, polarization switch matrix circuits, intermediate frequency receivers and power and control circuits) were each designed as separate packages. The distinct, separate packages of the antenna-converter system were then interconnected with each other to form an assembled antenna-converter system through the use of cables and connectors. This conventional assembly method, however, has proven to provide unsatisfactory performance for several reasons. For example, the use of cables and connectors for interconnecting the separate antenna and converter packages often results in degraded system performance due to signal losses in the cables and decreased system reliability. Furthermore, the use of separate packages for the antenna and various converter circuits increases the required size and overall weight of the antenna-converter system. US-A-4,411,022 discloses an integrated circuit mixer while EP-A-0 377 155 discloses an antenna incorporating a plurality of concentric waveguide cavities. SUMMARY OF THE INVENTION The invention relates to an integrated antenna-converter, comprising: an antenna section having means for receiving and radiating electromagnetic signals in the form of electromagnetic waves; a converter circuit section including means for processing electromagnetic signals, the converter circuit section implemented on at least one circuit board individually, mechanically and electrically connected to the means for receiving and radiating electromagnetic signals, wherein the at least one circuit board for the converter circuit section directly mount to the antenna section; and polarization matrix switch means comprising a circuit board electrically connected to a circuit board of a feed network circuit means for the converter circuit section characterized in that the circuit board for the polarization matrix switch means is mounted to at least one circuit board for the converter circuit section and mounted to the antenna section to fabricate, in a unitary package, an integrated antenna-converter. BRIEF DESCRIPTION OF THE DRAWINGS A more complete understanding of the integrated antenna-converter in a unitary package of the present invention may be had by reference to the following Detailed Description when taken in conjunction with the accompanying Drawings wherein: FIGURE 1 is an exploded schematic view of the integrated antenna-converter in a unitary package of the present invention; FIGURE 2 is an assembled view of the unitary antenna-converter package as shown in FIGURE 1; FIGURE 3 is a front view of the coaxial waveguide antenna utilized in the unitary antenna-converter package of the present invention; and FIGURE 4 is a side cross-sectional view of the integrated coaxial waveguide antenna and converter circuit disks of the unitary antenna-converter package of the present invention. DETAILED DESCRIPTION OF THE DRAWINGS Reference is now made to FIGURE 1 wherein there is shown an exploded schematic view of the integrated antenna-converter in a unitary package 100 of the present invention. The unitary package 100 is comprised generally of an antenna section 102 integrated with, and mounted to a converter section 104 in a manner to be described. The antenna section 102 contains the hardware required for receiving and generating electromagnetic waves carrying electromagnetic signals in one or more predetermined frequency ranges. The converter section 104 contains the circuitry required for implementing the radio frequency, intermediate frequency, polarization switch matrix and power-control circuits associated with receiving, generating and processing electromagnetic signals received and output by the antenna section 102 in the form of propagating electromagnetic waves. The antenna section 102 is preferably a multi-cavity coaxial waveguide antenna 106 having a plurality of cavities 108 each sized for propagating electromagnetic waves in a different range of frequencies. The cavities 108 are defined by a plurality of conductive cylinders 110, each having an open end 112 and a closed end 114 (see also FIGURE 4). Multiple, sized cavities 108 form an antenna 106 capable of operation over multiple frequency ranges. The conductive cylinders 110 are concentrically positioned with respect to each other to share a common axis 116. Each closed end 114 of a conductive cylinder 110 for the coaxial waveguide antenna 106 is terminated by a shared conductive plate and a plurality of probes (shown in FIGURES 3 and 4). The probes generate and receive, in the cavities 108, electromagnetic signals in the form of electromagnetic waves propagating in the frequency range dictated by the size of the cavity. It will, of course, be understood that the antenna section 102 may include only a single cavity 108 for propagating electromagnetic signals in a single frequency range, or have a different waveguide shape (for example, multi-cavity rectangular), if desired. With the advent of monolithic microwave integrated circuit (MMIC) manufacturing techniques, it has become possible to integrate the necessary circuits for the converter section 104 of an antenna-converter system on one or more small area substrates 118 (for example, the circuit disks shown in FIGURE 1). Such fabrication of integrated microwave circuits enables the circuit designs implemented on each disk substrate 118 to be connected to each other and to other disks with a fewer number of interconnects than with conventional signal degrading, RF cable interconnect designs. Furthermore, interconnection of the disks 118 provides a circuit package containing all necessary converter circuits occupying a relatively small volume. In the antenna converter implementation disclosed herein, MIC/MMIC fabrication allows for integration of all necessary circuits of a radio frequency feed network for the converter section 104 on a single small area feed network disk 120. Polarization switch matrix control circuits, intermediate frequency converters, and power and control circuits for the converter section 104 are similarly capable of integration on a polarization switch matrix disk 122, intermediate frequency disk 124 and power and control circuit disk 126, respectively. Each MMIC implemented disk 120-126 has a center 128 that is aligned with the axis 116 for the plurality of concentric cylinders 110 comprising the coaxial cavity antenna 106. The concentric cylinders 110 and disks 118 of the antenna section 102 and converter section 104 as shown in FIGURE 1 are assembled along axis 116 with the disks of the converter section 104 sandwiched together and mounted directly to, and flat against the back of the antenna section 102 to fabricate the integrated antenna-converter in a unitary package 100 shown in FIGURE 2. Furthermore, with MMIC implementation of the circuits, the circular area provided for each disk substrate 118 is chosen such that the perimeter of the substrate does not extend outside an envelope, shown generally by broken lines 130, for the antenna section 102. The envelope 130 is an imaginary volume extending in a rearward direction from the back of the antenna. The size and shape of the envelope 130 is dictated by the size and shape of the outer surface of the antenna section 102. With a coaxial antenna 106 as shown, the envelope 130 is a cylindrical volume defined by the outer surface of the outermost concentric cylinder 110. It is within this cylindrical volume that the sandwiched disk substrates 118 for the converter circuit section 104 must fit to form the unitary package. A connector 132 is provided to feed power and control signals to the converter circuit disks 120-126 to enable operation of the unitary antenna-converter package 100. Reference is now made to FIGURE 4 wherein there is shown a side cross-sectional view of the integrated antenna-converter in a unitary package 100 of the present invention. The antenna section 102 of the package 100 is a coaxial waveguide antenna 106 comprised of a plurality of concentric conductive cylinders 110, each cylinder having an open end 112 and a closed end 114. The termination for the closed end 114 of the assembled concentric cylinders 110 is a conductive plate 136. The size of each cavity 108 of the antenna 106 is selectively chosen to propagate electromagnetic waves in a predetermined range of frequencies. For example, in the embodiment shown in FIGURE 4, the sizes of the cavities are selected such that cavity 108(1) operates over the 2-3.5 GHz range, cavity 108(2) over the 3.5-6 GHz range, cavity 108(3) over the 6-10 GHz range and cavity 108(4) over the 10-18 GHz range. The embodiment shown is thus capable of operation over a broad range of frequencies from two to eighteen gigahertz. The probes 134 at the closed end of each cavity 108 receive and radiate electromagnetic waves only in the frequency range dictated by the size of the cavity. To process the electromagnetic signals received by the probes 134 or generate a signal for radiation by the probes, the probes associated with each cavity 108(1)-108(4) are connected to a separate feed network disk 120(1)-120(4), respectively. Each feed network disk 120 contains circuits designed to operate over the frequency range for the cavity 108 electrically coupled thereto. Thus, each feed network disk 120 includes MMIC implemented modulation and demodulation circuitry (including a radio frequency converter and several sub-bands of a converter). It will, of course, be understood that the requisite radio frequency converter circuits for all operating frequencies of the antenna section 102 may be MMIC implemented on a single disk 120, as shown in FIGURES 1 and 2, if the area needed for the circuits results in a disk size that fits within the volume of the antenna envelope 130 (see FIGURE 1) when mounted to the back of the antenna. The connection between each antenna cavity 108 and associated feed network disk 120 is made using a short piece of coaxial line 138 with the inner and outer coaxial conductors at one end connected to the probe 134 and plate 136, respectively. At the other end of the line 138, the inner and outer conductors are connected to a microstrip line on the feed network disk 120 using a right angle coax-to-microstrip transition (generally indicated at 140). When the microwave circuits on the disks are implemented with striplines, similar interconnect methods may be used. The converter section 104 further includes polarization switch matrix circuits, intermediate frequency converter circuits and power and control circuits implemented on one or more disks 142 using MIC/MMIC technology. The connections between the feed network disks 120 and the remaining converter disk(s) 142 are made using short pieces of coaxial line 138 with the ends of the line connected to the microstrip lines of each disk using right angle coax-to-microstrip transitions 140. Connections between the various disks utilized in the converter section 104 and external power supply, command and control, and processing circuits may be made via a connector 132 and/or a coaxial line 138 as desired or needed.

Claims: An integrated antenna-converter, comprising: an antenna section (102) having means for receiving and radiating electromagnetic signals in the form of electromagnetic waves; a converter circuit section (104) including means for processing electromagnetic signals, the converter circuit section (104) implemented on at least one circuit board (120-126) individually, mechanically and electrically connected to the means for receiving and radiating electromagnetic signals, wherein the at least one circuit board (120-126) for the converter circuit section (104) directly mount to the antenna section (102) ; and polarization matrix switch means comprising a circuit board (122) electrically connected to a circuit board (120) of a feed network circuit means for the converter circuit section (104), characterized in that the circuit board (122) for the polarization matrix switch means is mounted to at least one circuit board (120-126) for the converter circuit section (104) and mounted to the antenna section (106) to fabricate, in a unitary package (100), an integrated antenna-converter. The integrated antenna-converter as in Claim 1 further comprising: intermediate frequency circuit means comprising a circuit board (124) electrically connected to the circuit board (122) for the polarization matrix switch means, the circuit board (124) for the intermediate frequency circuit means mounted to the circuit boards (122, 120) for the polarization matrix switch means and the feed network circuit means and mounted to the antenna (106) to fabricate, in a unitary package (100), an integrated antenna-converter. The integrated antenna-converter as in Claim 2 further comprising: power and control circuit means comprising a circuit board (126) electrically connected to the circuit board (124) of the intermediate frequency circuit means, the circuit board (126) for the power and control circuit means mounted to the circuit boards (124, 122, 120) for the intermediate frequency circuit means, the polarization matrix switch means and the feed network circuit means and mounted to the antenna (106) to fabricate, in a unitary package (100), an integrated antenna-converter. The integrated antenna-converter as in one of the proceeding claims wherein the antenna (106) comprises a waveguide antenna having a plurality of waveguide cavities (108) each sized for propagating electromagnetic signals in a predetermined frequency range. The integrated antenna-converter as in Claim 4 wherein the waveguide antenna further includes a plurality of concentric conductive hollow cylinders (110) terminated at one end by a conductive plate (136), each cylinder (110) having a predetermined diameter defining a plurality of cavities (110) sized for propagating electromagnetic waves in the predetermined frequency ranges. The integrated antenna-converter as in Claim 5 wherein the means for receiving and radiating electromagnetic signals comprises: a plurality of electric field probes (134) positioned within each cavity (108) of the waveguide antenna (106) at the end terminated by the conductive plate (136). The integrated antenna-converter as in one of the preceeding claims wherein the antenna (106) size and shape defines an antenna envelope volume (130) extending away from the antenna (106), and wherein each circuit board (120-126) has a perimeter -that fits within the defined antenna envelope volume (130) when mounted to the antenna (106). The integrated antenna-converter as in Claim 1 wherein each circuit board (120-126) of the converter circuit means (104) comprises a monolithic microwave integrated circuit with each electromagnetic probe (134) connected to the converter circuit means (104) on a circuit board (120-126) by means of a coaxial line (138) extending between the cavity (108) and the circuit board (120-126).

Inventors: AGARWAL KRISHNA KUMAR, SHEA DONALD FRANK, AGARWAL, KRISHNA KUMAR, SHEA, DONALD FRANK
Applicants: E SYSTEMS INC, E-SYSTEMS INC.
Application year: 1993
Main classification: H01Q1
IPC codes: H01Q1, H01Q5, H01Q13