Abstract: A planar array antenna having a switching matrix that couples an RF signal to two distributed ferrite scanning line feeds that feed a planar continuous transverse stub array antenna. The scanning line feeds couple RF energy to the antenna from opposite sides to form a total of four beams offset in space that each cover different angular scan sectors. The antenna has reduced complexity and lower design and production costs. The use of dual ferrite scanning line feeds, the switching matrix, and the continuous transverse stub antenna to obtain wide-angle scanning provides significantly improved performance. The present invention uses the two distributed ferrite scanning line feeds to obtain greater scan coverage at upper millimeter-wave frequencies, where realizable ferrite materials are less active and provide diminished scan capability. The scanning line feeds and planar array antenna may be designed so that the four scan sectors are contiguous, to increase the angular scan coverage of the antenna.

Abstract: A phased-array antenna structure is provided that includes an antenna waveguide structure with a plurality of waveguides. The antenna waveguide structure propagates the received or transmitted electromagnetic (EM) signals within the plurality of waveguides to a corresponding active array module. Each active array module amplifies and adjusts the phase of a received or transmitted EM signal. The active array modules are coupled to an interconnect structure that provides EM signal propagation paths, as well as power and digital signal paths, to and from the active array modules. A plate is coupled to the interconnect structure and the antenna waveguide structure to support the antenna waveguide structure, the electronic modules, and the interconnect structure, thereby forming a rigid unit and keeping the electronic modules in alignment with their corresponding waveguides in the antenna waveguide structure.

Abstract: A feeder horn for two-way satellite telecommunications includes a center transmitter/receiver horn (10) and at least three separate measuring (11, 12, 13) which are positioned symmetrically relative to the symmetry (O) of the feeder horn.

Abstract: A siamese feedhorn for a satellite receiving antenna capable of simultaneously receiving signals from satellites in different geostationary satellite positions. The siamese feedhorn preferably includes a first waveguide section mated with a second waveguide section. The first waveguide section is preferably positioned at the antenna's focal point to receive signals from within the antenna's beamwidth. The second waveguide section is positioned at an offset distance from the focal point to receive signals from a satellite in a different geostationary position.

Abstract: A pyramidal horn antenna that decreases ringing in radar systems that are placed against a solid volume of e.g. concrete or wood for finding an object in or behind the solid volume. The antenna includes a solid, pyramid-shaped dielectric, the pyramid shape including a rectangular base and four triangular sides that extend from the base to meet at the apex of the pyramid. Two conductive triangular plates overlay opposite ones of the four sides of the pyramid, each of the plates including an electrical connection for coupling the plate to a radar system. The pyramid-shaped dielectric has a dielectric constant that approximates the dielectric constant of the solid volume, and therefore provides an impedance match between the antenna and the solid volume.

Abstract: A single integrated antenna feed transmits and receives electromagnetic waves in the C, X, and Ku frequency bands. This antenna feed includes an inner metal tube which lies along a central axis, and an outer metal tube which surrounds and is coaxial with the inner metal tube. Through the inner tube, a passageway is provided which is sized to carry electromagnetic waves in the X-band and Ku-band, but reject electromagnetic waves in the C-band. Between the inner tube and the outer tube, another passageway is provided which is sized to carry electromagnetic waves in the C-band. An I/O port for the X and Ku-bands is provided by a first end of the inner tube, and an I/O port for the C-band is provided by a corresponding first end of the outer tube. This first end of the outer tube lies proximate to but not past the first end of the inner tube. A solid dielectric is inserted into and fills the first end of the inner tube; and, a hollow metal cone is attached to the first end of the outer tube.

Abstract: An assembly of antenna elements is mounted in a unitary structure for transport on a satellite encircling the earth. Each element comprises a horn shaped radiator with opposed arcuate sidewalls, a rectangular waveguide feed, and a transition interconnecting the feed to a throat of the horn. The assembly services a plurality of portions of a communication band within the electromagnetic spectrum. The throats of respective horns are dimensioned for specific frequencies of the respective portions of the communication bands. The antenna elements may provide telemetry and control functions for the satellite. A side-by-side arrangement of the horns permits use of a common meanderline polarizer for conversion of a linearly polarized wave to a circularly polarized wave for each antenna element.

Abstract: A unitary waveguide element is employed in a light weight waveguide antenna. The waveguide element has a waveguide portion having a front wall with slots formed across it at predetermined locations, a continuous back wall, and substantially continuous broad walls. A first flange is formed on one of the broad walls lying in a plane that extends in the width direction. A pair of flanges are formed on the other broad wall that lie in planes that are displaced slightly from the first flange, so that when the waveguide element is superposed onto the next successive element, these flanges overlap with the second flanges straddling the first flange. The flanges are then bonded with epoxy or an equivalent agent. A rivet box is formed on the proximal side of the back wall and permits attachment of the waveguide element in precise alignment to a predrilled backing plate with rivets or other suitable fasteners. The rivets do not penetrate into the waveguide portion of the element.

Abstract: Planar microwave antennas are described of the type formed from a plurality of moulded planar layers. A first layer defines horn elements and two underlying layers define waveguide channels communicating with the horn elements. The waveguide channels are formed at the interface between layers by aligned channels in the abutting surfaces. The surfaces of at least the horns and waveguide channels are metallised, and the layers may be secured together by rib welding.

Abstract: A device for distributing a microwave signal in an array antenna to a number of radiating elements includes a main branching point at which the microwave signal is distributed to a first and a second antenna section. Each antenna section has a number of branching points connected in series, each of which distributes the microwave signal supplied to the branching point between a waveguide, connected to the branching point, and the next branching point connected in series. A number of parallel branches are connected to the waveguide. These parallel branches distribute the microwave signal supplied through the waveguide between the radiating elements.

Abstract: A multiband phased-array antenna interleaves tapered-element radiators with waveguide radiator to facilitate the simultaneous radiation of antenna beams across a bandwidth in excess of two octaves. The launch ends of the waveguide radiators collectively define a ground plane. The tapered-element radiators have pairs of tapered wings which are extended past the ground plane by a distance which is selected to establish a predetermined tapered wing radiation impedance. The radiators of each type are spaced apart by a span which insures that they will not generate grating lobes at the highest frequency which they respectively radiate.

Abstract: A microwave cavity filter (30, 30A) is formed of a section of waveguide (36, 114) terminated by end walls (38, 40, 44, 166, 168, 176) to form cavities (32, 34, 32A, 34A) wherein ridges (100, 102, 118, 120) are disposed longitudinally within a cavity and extend from the cavity wall partway to a central region (104, 124) of the cavity. In a preferred embodiment of the invention, the ridges are disposed symmetrically about a central plane (144), each ridge having a first component (106, 122) perpendicular to the central plane and a second component (108, 126) parallel to the central plane. A cross-sectional shape of a filter cavity may approximate a semicircle wherein one wall section (88, 130) of the filter cavity is disposed within a diametric plane (216) of the cavity. The end walls of the cavities may be constructed as iris plates with apertures (82, 182, 184, 186, 190) for coupling energy of selected modes of electromagnetic resonance within the respective cavities.

Abstract: A plurality of dual mode, dielectric resonator loaded cavity filters may be coupled to respective ones of a plurality of radiators of an array antenna, such as a phased array antenna. Each of the filters is provided with a thin annular, electrically conductive ring disposed on a resonator surface facing the corresponding radiator of the antenna. The ring greatly increases the coupling of electromagnetic power for circularly and linearly polarized waves between the filter and the radiator for radiation of the power from the radiator into space, as well as during reception of radiation from outer space. The filter is operative also, if desired, to provide such coupling of electromagnetic power to a waveguide, as well as directly into the external environment. The ring may be located at the opening of the cavity through which the power is coupled between the filter and the radiator or the waveguide or the empty space.

Abstract: A module formed by an array of pipes is provided for installation in front of existing radar and sonar transducers. A preferred array is formed by a section of honeycomb material in which each pipe has a hexagonal cross section and is mounted in an insulating sheath. Each pipe acts as a radiator of energy from a transducer that combine in phase to produce a beam narrower than the beam from the transducer. The module is effective to improve the range and resolution of forward-looking radar and sonar devices.

Abstract: A microwave radar antenna that substantially comprises molded or extruded thermoplastic components that are assembled into completed assemblies, are then metallized by either electroless copper or are electroplated with copper to achieve RF conductivity. The finished subassemblies are joined together forming the completed antenna. The molded, metallized, plastic antenna uses a thermoplastic material, such as polyetherimide, or suitable high strength, high temperature thermoplastic that is used to injection mold or extrude detailed microwave components. The molded components are assembled, using epoxy adhesives, solvents or other mechanical method into microwave subassemblies. These subassemblies are then either electroless copper plated or electroplated to provide RF conductivity. The metallized subassemblies are then joined together using mechanical methods to form a completed radar antenna, replacing heavier more costly metal radar antennas.

Abstract: A feed structure (24) is disclosed for reception of orthogonal linearly polarized signals from communication satellites. The structure includes probes (34, 36) extended through the back wall (32) of a cavity (28) with associated transmission members (50, 52) and an associated isolation member (54). The teachings of the invention are extended to structures having the probes extended through the side wall (100) of a cavity. The teachings of the invention are further extended to dual band feed structures (124, 220 and 320). The structures are particularly suited to enhance high signal to noise ratios because of short path lengths to external receiver circuits and to enable realization in simple economical one piece castings.

Abstract: A dual band signal receiver is provided with relatively coaxial antenna assemblies electromagnetically coupled to respective upper and lower band rectangular waveguides and ports through suitable polarization switching assemblies. The upper band rotatable antenna assembly consists of a dipole feed having driven dipole elements, parasitic dipole elements and a corner reflector element electromagnetically coupled to the upper band rectangular waveguide by a suitable transmission line extending substantially along the longitudinal axis or centerline of the lower band cylindrical waveguide.

Abstract: A unitary array of efficient directional corrugated feed horns, each having a desired corrugated horn cross-section within close tolerances, as well as accurate positioning and orientation relative to each other. The unitary array structure is comprised of a plurality of thin platelets which are laminated together in a selected sequence. The unitary array design provides a mechanical structure to support millimeter and sub-millimeter wavelength electronic devices for reception or transmission of electromagnetic energy and cooling fluid circulation channels within the array to remove unwanted heat generated by the attached electronic devices. The design of the present invention affords a relatively lightweight structure through removal of unneeded materials by forming cavities within the structure while leaving sufficient material for the bonding of the platelet assembly.

Abstract: An array of five, ridge waveguide horns provides monopulse operation over a wo octave range. A unique coax-to-ridge waveguide input coupler and an extended ridge matching section at the radiating apertures provide the extended frequency range. The horn assembly is lightweight, compact and suitable for array applications. A five horn monopulse primary feed array is exemplified.

Abstract: An antenna having antenna modules for an extremely wideband active monopulse phased array system, the modules including a housing provided with four radiators of the rectangular open-ended waveguide type and with an electric circuit. With the antenna modules being suitably stacked, the radiators constitute a substantially continuous antenna surface, the radiators being positioned at the points of intersection of a system of equilateral triangles which make up the antenna surface. After preamplification, phase shift and down-conversion to an intermediate frequency, received signals from a large number of antenna modules are combined to yield a sum beam, an azimuth difference beam and an elevation difference beam.

Abstract: An antenna for the radiation of ultra-wideband pulsed electromagnetic radiation. The invention is a high gain, transverse electromagnetic parallel-plate, open-sided transmission-line array horn antenna utilizing a binary tree-based design, which produces a multiple number of paralleled horns and final radiation apertures, connected to a single signal feed waveguide. This invention antenna structure produces an equal path length for the signals in each of the paralleled branches, virtually eliminating phase error in the E plane and producing high gain characteristics over most of the desired radiation frequency range.

Abstract: Monolithic microwave integrated circuit (MMIC) technology is advantageously used to fabricate microwave circuitry for an antenna-converter system to enable an antenna and its associated converter circuits to be integrated together into a unitary package. 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 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.

Abstract: A shaped beam antenna system which provides a desired shape of beam, comprises a reflector and at least one primary radiator located essentially at focus of said reflector. Reflection surface of the reflector is a dense set of parabolas in which vertexes of said parabola shift on a predetermined locus which is preferably a three dimensional space curve, but not a plane curve. A second feature of the shaped beam antenna system is the primary radiator which is composed of a plurality of primary radiators positioned closely to each other.

Abstract: A waveguide feeding array antenna is provided to be capable of separating and taking up each of the polarization components of the horizontal and vertical polarized waves received concurrently at an opening of each of a plurality of waveguides arranged to form a network, by means of a taking-up equipment disposed in the waveguide circuit. The both polarization components can be made thereby to be effectively separated from and composed with each other while realizing the simplification and economization of the waveguide network.

Abstract: A millimeter wave imaging system receives millimeter wave radiation and provides video imaging signals based thereon. The system comprises an imaging lens for receiving incoming radiation; a focal plane antenna array disposed at the focal plane of the lens on which radiation received by the lens is focussed; and signal processing and display circuitry for processing the output of the antenna array and for producing and displaying corresponding video imaging signals. The focal plane antenna array comprises a planar array of a plurality of conical horns and circular waveguides which, in use, are disposed at the focal plane of the lens; and a microstrip detector assembly coupled to the waveguides for detecting the radiation received thereby. The microstrip detector assembly comprises a dielectric substrate having a plurality of microstrip conductors embedded therein, each microstrip conductor being coupled to a respective one of the waveguides, and a diode detector being connected to each microstrip conductor.

Abstract: A feed structure (24) is disclosed which facilitates reception of orthogonal linearly polarized signals from communication satellites. The structure includes probes (34, 36) combined in a cavity (28) with transmission members (50, 52) and an isolation member (54). The structure is particularly suited to enhance high signal to noise ratios because of short path lengths to external receiver circuits and to enable realization in simple economical one piece castings. The teachings of the invention are shown extended to dual band feed structures (124).

Abstract: An improved microwave radar antenna including a plurality of linear waveguides arranged in a two dimensional array with each linear waveguide having a mounting flange along the bottom narrow edge of the waveguide for attachment to the ground plane of the antenna by the conductive epoxy. Also disclosed is a method of manufacturing an improved microwave antenna where flanged linear waveguides are milled to provide for radiator slots and then are affixed to a attentive ground plane along the flanged edge of the waveguide by a conductive epoxy.

Abstract: A multiple beam array antenna that is designed with an aperture shape which conforms to the particular coverage area to which the antenna is directed. The antenna consists of individual horn antennas (20) that are nested together to form the array (14). The outer walls (50) of the peripherally disposed horn antennas (40) are individually shaped such that the combined shape of the outer walls (50) of the peripherally disposed horn antennas (40) determine the perimeter shape of the aperture (12) of the horn array (14). Where the desired coverage area is circular, elliptical or irregularly shaped, the shape of the perimeter of the aperture (12) of the horn array (14) is similarly circular, elliptical or irregularly shaped, respectively.

Abstract: A dual frequency feed assembly employing a pair of coaxial circular wave guide cavities, each with respective probe. The higher frequency cavity, e.g. Ku band, is located within the lower frequency, e.g. C band cavity. A common motor is used to drive the two probes which have a common axis A. The lower frequency probe is coupled through the rear wall of the assembly to a rectangular waveguide. The higher frequency probe is also coupled through the rear wall of the assembly but via a coaxial line which is diverted from the axis A to exit beside the lower frequency waveguide. The two rectangular waveguides and the drive motor for the probes are all mounted on the rear of the assembly. In one embodiment of the invention the coaxial line extends from its probe to a housing on the body containing a signal processing circuit board. Connection to that board is made directly eliminating the need for any waveguide transmission line.

Abstract: A planar antenna of the kind comprising feed lines disposed in a flat circuit and cooperating by hyperfrequency coupling with a metal ground plane plate pierced by apertures has the feed lines presenting a termination juxtaposed with each aperture. A lower ground plane plate is disposed at a distance of approximately a quarter wavelength from the apertured metal plate. The apertured metal plate comprises a metal coating deposited on a dielectric substrate. The feed line comprise central conductors disposed in channels which open into the apertures. The array of apertures, channels and conductors can be produced on the dielectric substate by single face printed circuit techniques. The antenna may be used for the reception of direct broadcasts from satellites.

Abstract: A waveguide array comprising a plurality of waveguides which are each outwardly tapered at the aperture of the array in accordance with a predetermined criteria chosen to increase waveguide efficiency. The tapering serves to gradually transform a fundamental Bloch mode, propagating through the waveguide array, into a plane wave in a predetermined direction, and then to launch the plane wave into free space in the predetermined direction. In another embodiment, the waveguides are positioned relative to one another in order to satisfy the predetermined criteria.

Abstract: The I.F.F. sum and difference channels are obtained by means of the reflector of the radar, illuminated by primary radiating elements associated with the horn of the primary source of the radar. Furthermore, the signals of the I.F.F. sum and difference channels are suitably mixed to obtain a reduction in the level of the cross-polarized signals.

Abstract: A TO-style plug-in package for MMICs and associated antenna structure is comprised of a microwave circuit component carrier having a generally cylindrically shaped conductive header upon which one or more MMICs are supported. An aperture through the header contains a conductor pin supported within a glass seal interface, so as to form a hermetically sealed matched impedance transmission line through the package. The conductor pin is connected to a bonding pad of a microwave circuit component on the header. A generally cylindrical conductive cover engages the header and encloses a cavity within which the microwave circuit components are supported. A microstrip antenna is supported on a dielectric layer overlying an outer surface of the conductive cover and is connected to a further conductor pin that extends through a glass-sealed aperture in the cover and forms a matched impedance transmission line from the antenna to the header.

Abstract: A plurality of conical transmission lines are concentrically nested to form n output antenna for pulsed-power, radio-frequency, and microwave sources. The diverging conical conductors enable a high power input density across a bulk dielectric to be reduced below a breakdown power density at the antenna interface with the transmitting medium. The plurality of cones maintain a spacing between conductors which minimizes the generation of high order modes between the conductors. Further, the power input feeds are isolated at the input while enabling the output electromagnetic waves to add at the transmission interface. Thus, very large power signals from a pulse rf, or microwave source can be radiated.

Abstract: A constant E-plane beamwidth antenna (10), includes a rectangular feeder (12) communicating with a partly cylindrical sectoral horn (14) via a transition (30) positioned in the throat of the sectoral horn. The transition (30) has a plurality of electrically conductive partitions (32) positioned perpendicular to the electric field of a mode propagating, in use, in the sectoral horn (14). The disposition of the electrically conducting partitions is arranged to transport modes which have a constant plane across the surface on one side of the transition into modes which have a constant phase across the surface on the other side of the transition. The transition (30) may be used to control the E-plane beamwidth of an H-plane constant beamwidth horn. Optionally the spaces between the electrically conductive partitions (32) may be filled with a low loss dielectric material.

Abstract: A dual band integrated feedhorn includes a housing having a rotatable support for a C band coaxial waveguide, a clamp for a Ku band waveguide, a Ku band waveguide slideably mounted in the clamp for focus adjustment, and a pair of low noise blocks connected to the waveguide output probes for downconverting their incoming modulated carrier C and Ku band signals to modulated IF signals. A servo drives the support member to position the waveguides energy output coupling probes to match the polarization of the incoming RF energy; thus, eliminating the need for polarizers and reducing insertion loss significantly. The reduced insertion loss enables defocusing of the Ku band waveguide to widen the half power beamwidth to improve aiming accuracy without decreasing the gain and degrading performance. A position adjustable scalar and a pair of power modules are attached exteriorly of the housing. The scalar is positioned adjacent the end of the C band waveguide for focusing the C band waveguide.

Abstract: A horn radiator assembly includes two horn radiators each of which is formed as a conical horn and a waveguide of constant cross section connected to the small end of the horn as a feed and providing a signal port. The first of the horn radiators is of relatively large cross section and serves to radiate electromagnetic waves at a relatively low frequency. The second of the horn radiators is of relatively small cross section and serves to radiate electromagnetic waves at a relatively high frequency. The second radiator is nested within the first radiator, and is positioned with its radiating aperture coplanar with the radiating aperture of the first radiator. In the second radiator, the waveguide feed is provided with a bend allowing the waveguide feed to pass through a wall of the first radiator. A strut may be affixed to the bend to provide a symmetrical transverse support within the first radiator for the second radiator.

Abstract: An antenna is constructed of an array of contiguous circular cylindrical radiators each of which extends forwardly of a radiator assembly producing two circularly polarized waves of opposite direction of rotation of their respective electric fields. The radiators measure one wavelength at the transmit frequency band, and approximately 1.5 wavelengths in diameter at the receive frequency band. A section of cylindrical waveguide in the back of each radiator assembly encloses a microwave structure for generating the circularly polarized waves, the microwave structure including an orthomode transducer at the back of the assembly and an electric field rotator disposed forward of the orthomode transducer. In each radiator assembly, there is disposed between the rotator and the radiator a transition between smaller diameter waveguide to larger diameter waveguide. The transition may have the form of a step or a flare for a more gradual transition. The transducer produces a higher order TM.sub.

Abstract: An improved corporate feed network for distributing radio frequency energy to elements of an antenna array is shown. The corporate feed network comprises an improved feed coupler, including a quadrature hybrid junction for dividing radio frequency (R.F.) energy from an input port into the two waveguides and a plurality of secondary waveguides disposed orthogonally to the first and second waveguides, each of the secondary waveguides having narrow walls common to broad walls of the first and second waveguides with apertures formed through common sections of such walls, the common sections being offset to impart directional characteristics to the corporate feed network.

Abstract: A fabricated dielectric aperture assembly includes a first layer of electrically conductive material having an opening therethrough to define a first aperture, a second layer of electrically conductive material spaced from the first electrically conductive layer and having an opening therethrough to define a second aperture and a plurality of solid dielectric layers interposed between the first and second layers of electrically conductive material. The first and second layers of electrically conductive material with the multiple layers of dielectric material interposed therebetween form a generally laminar assembly. A grid-like structure is embedded in the laminar assembly and extends between the first and second electrically conductive layers. The grid-like structure has an inner wall, an outer wall portion, an interior bounded by the inner wall and a plurality of openings extending from the inner wall to the outer wall.

Abstract: An antenna has a resonant cavity defined by electrically conducting plates and a sidewall, and has sixteen helical antenna elements each with five turns in the helical section and a probe at the opposite end, the stem of probe passing through an aperture in upper plate so that its end is within the resonant cavity common to all elements in that module.The cavity has a cross-section parallel to the plates essentially square in shape except for the presence of four inwardly-protruding buttresses, one situated mid-way along each side of the cavity to promote the formation of standing waves of different mode, and thereby enhance the frequency range of the array.

Abstract: A dual frequency feed assembly for antenna systems employing a pair of rotatably mounted probes each in respective coaxial cavities. The smaller cavity is supported by the rotating means for the larger probe and the smaller probe rotates with the larger probe driven by a common motor. The higher frequency signal is taken from the side wall of the lower frequency cavity. In an alternate embodiment, the smaller cavity is supported by a spider which rotates the smaller probe by means of external gearing and a separate motor. Other embodiments show coaxial lines which enter from the front face of the assembly and allow rotation of the smaller probe.

Abstract: A dual frequency antenna feed is formed from a central, circular waveguide onnected to the flat boundry of circular, disk-shaped resonant cavity. A second circular waveguide is connected one end of a disk-shaped resonant cavity. Energy of one frequency enters and exits the cavity along the common axis of the waveguides. Energy of the second frequency is introduced to the same resonant cavity by way of a plurality of bandpass filters, also connected to the cavity. This energy enters by way of slots in the cylindrical walls of the cavity. The central circular waveguide is propagating at one frequency but cut off at the second frequency. These bandpass filters are at this pass band for the second frequency, but at the rejection band for the first frequency. Therefore, the isolation between these two input ports are obtained.

Abstract: Close tolerance waveguide assemblies for use in antenna arrays is disclosed. In particular, the waveguide assemblies are configured along the zero electrical current lines in the antenna array. Such waveguides are particularly useful in antenna arrays for radar systems operating at the microwave and millimeter-wave frequencies. In the invention, antenna array assemblies, such as rectangular or ridged waveguide assemblies, are configured by combining plates which are formed into a plurality of equal length members protruding from and perpendicularly disposed to a structural member, wherein each such protruding member has two formed or unformed ends.

Abstract: A dual frequency band microwave antenna feed for a parabolic reflector has a circular waveguide for a low frequency band and a smaller circular waveguide for a higher frequency band disposed in and concentric with the low band guide. A twisted conductive baffle is disposed in each guide to permit 90.degree. rotation of linearly cross-polarization signals and a pair of in-line ports is attached to each guide for output of such pairs of cross-polarization signals.

Abstract: A dual-band linear cross-polarized antenna waveguide comprising a coaxial pair of waveguides, with the higher frequency band waveguide contained completely within the TE.sub.01 mode null of the lower frequency band. The lower frequency waveguide completely surrounds and is concentric to the higher frequency waveguide.

Abstract: A directional antenna is provided having an array of directional antenna elements arranged in at least one row. The directional antenna elements are activated in accordance with a predetermined pattern. The signal amplitudes on the receiving side are time-shifted to simulate a low-frequency signal for detection of deeper-lying anti-tank mines. Each directional antenna element has a pair of flat strips which lie close to each other at the base side and which proceed in parallel before diverging to a greater width toward the aperture side.

Abstract: An angular-diversity radiating system is described for tropospheric-scatter radio links which comprises a paraboloid and two antenna horns in which the distance between the antenna horns is adjustable in order to vary the diversity angle depending on the transmissive characteristics of the troposphere of the link involved to always have the optimal diversity angle under all link conditions.The radiating system includes four wave guides connected to the two antenna horns to permit the use of single and double polarization for both the antenna horns and the use of both the antenna horns, or alternatively only one, for receiving and transmitting signals.

Abstract: An array of flared horn antennas is adapted to be fed from circular waveguide. The apertures of the horns are closely spaced. Prior art horns with circular apertures leave gaps in the aperture. The gaps are eliminated, and the gain of the array is increased by about 1/2 dB by tapering the horns from a circular cross-section at the feed end to a hexagonal cross-section at the radiating aperture end.

Abstract: A high-frequency antenna unit module for receiving or transmitting a rectilinearly polarized wave including radiating elements in the form of horns and a waveguide supply network. The module has four horns with square apertures which form a bidimensional network in a plane parallel to a reference plane P. The supply network is of the "planar" type having first pairs of opposing sidewalls extending in a direction parallel to P, and of the "tree-structured" type because all of the horns are fed in-phase by T-shaped power dividers. The waveguide sections have sidewall dimensions a and b, where a>b and a=.lambda..sub.c /2. The dimension b is the width of each of the opposing sidewalls extending parallel to P, and a is the height of opposing sidewalls extending perpendicularly to P and connecting each of the first pairs of sidewalls. The network is suitable for propagating the TE.sub.01 mode along which the electric field vector E propagates in parallel with the plane P.