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: A package for a microwave circuit chip and associated microstrip antenna is formed of a multi-layer ceramic laminate within which is supported a microwave chip carrier and on an outer surface of which a microstrip antenna disposed. A first ceramic layer is supported on metallic base member and contains signal lines for interfacing the chip with the external world. Disposed atop the first ceramic layer is a second ceramic layer which forms a protective seal ring around the perimeter of the chip. A third ceramic cover layer is mounted atop the seal ring layer and contains one or more antenna elements on its outer surface. Signal line connections between the chip and the antenna elements are effected through tuned networks that extend from signal leads on the chip to conductors on the first ceramic layer. Signal connections from the first ceramic layer to the antenna on the cover may be formed by conductive vias through the ceramic seal ring layer or conductors along sidewalls of the seal ring layer and cover.

Abstract: A wideband hybrid horn antenna in which a circular section horn (1) is fed by a circular feed guide (3). A dielectric polyrod (7) is cantilever mounted in the throat end (4) of the horn (1) and is tapered to provide a match to the guide (3). Its forward section is tapered from the guide diameter down to about 2 mm just outside the mouth (11) of the horn (1). The various dimensions--horn diameter at throat and aperture, flare angle, polyrod diameter taper and extent--are all chosen to produce a balance of opposing effects on the beamwidth and thus provide a fixed beamwidth substantially independent of frequency over a wide band. A large bandwidth, from 8 to 16 GHz in the particular case, is thus obtained with a substantially constant beamwidth over the band.

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 photoconductive antenna modulator which optically modulates a radio frequency carrier signal from a dielectric waveguide antenna is disclosed. A photoconductor film is placed in proximity with the dielectric waveguide antenna such that the radio frequency carrier signal from the antenna must be conducted through the film when it is radiated into space. The carrier is then optically modulated by variably illuminating the photoconductor film with light which has wavelengths near the photoconductor film's spectral region of photoconductor sensitivity, which decreases the photoconductor film's transparency to the radio frequency carrier signal. By varying the strength of the illumination on the photoconductor film, one is able to optically modulate the radio frequency carrier signal propagated through the photoconductor.

Abstract: A device for exciting a waveguide with circular polarization from a plane antenna, said waveguide (10) being a rectilinear hollow waveguide closed at one of its ends (12), said antenna being excited by at least two coaxial ports (13, 14) fed in phase quadrature by a circuit including a hybrid coupler (15), and being constituted by a radiating plane metal pattern (11) disposed on the surface of an insulating substrate (18) closing the waveguide (10) perpendicularly to its axis of symmetry.

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 dual frequency feed for use with an antenna permits reception of signals in both a low frequency band and a high frequency band and is comprised of a single feed through which both signals are propagated, a high frequency probe which extends concentrically within the throat of the feed for receiving the high frequency signal, a wave guide connected to the throat of the feed including a pair of turnstile junctions with four wave guides interconnecting the turnstile junctions, and a single output port with a polarization rotation device for receiving the low frequency signal. The four interconnecting wave guides may be either co-axial cables or generally rectangular wave guides.

Abstract: The present invention relates to a two-frequency radiating device comprising a waveguide radiating in a first frequency range opening out into a radiating element operating in a lower, second frequency range. The invention is particularly applicable to antennas.

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: A hollow waveguide includes a conductive peripheral wall arrangement centered on a longitudinal axis. The waveguide is short-circuited at a first transverse plane. A center conductor is connected to the short-circuit and extends along the longitudinal axis to an abrupt open circuit termination at a second transverse plane. The arrangement is fed at a location between the first and second transverse planes to produce both a fundamental waveguide mode and a center-conductor coupled mode. The fundamental mode has an amplitude taper in the horizontal direction but not in the vertical direction. At the abrupt termination, a higher-order waveguide mode is generated which, when phase-shifted by 180.degree., provides an amplitude taper in a vertical direction. A radiating aperture located near the 180.degree. phase shift point produces a radiation pattern which is similar in both the verticla and horizontal planes.

Abstract: During multipath fading in a terrestrial digital radio system, off-axis arrival of signals excites higher-order modes in a horn reflector antenna. In the disclosed system specified ones of these higher-order modes and the fundamental mode are allowed to propagate in a main waveguide connected to the antenna. At least one of the higher-order modes is abstracted from the main waveguide and fed to a standby receiver while the fundamental mode is propagated intact to a main receiver.Error occurrences in the fundamental and higher-order modes due to multipath fading are substantially uncorrelated. Hence, upon detecting an error in the signals delivered to the main receiver, the system switches to the standby receiver thereby to provide in a single-antenna a significant improvement in performance against multipath fading.

Abstract: Scanning tip for electromagnetic radiation having wavelengths below about 3 cm comprising a waveguide (10) which acts as high-frequency hollow waveguide and which comprises a wall (12) of an electrically conductive material and the internal cross-section of which diminishes from a point at which it has a magnitude which permits unrestricted propagation of the radiation perpendicularly to the cross-sectioin to an end aperture (14) having a dimension (s) which is small in comparison with the wavelength of the radiation, having a rod (20) which comprises an electrically conductive surface which is electrically insulated with respect to an electrically conductive inner wall of the hollow waveguide and extends from the aperture (14) at least up to said location (z=0).

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 antenna is disclosed for increasing the gain of, or shaping the pattern of, a radiated radio frequency signal. The antenna includes a waveguide for directing the radio frequency signal or for receiving directively the radio signal, a first conductive reflector disposed beneath the waveguide and extending beyond the aperture of the waveguide for reflecting certain of the waves emanating from or entering the aperture of the waveguide, and a second reflector, which may be the mounting surface, disposed beneath the first reflector and extending beyond the first reflector for reflecting other of the waves emanating from or entering the aperture of the waveguide.

Abstract: A reflector antenna with a dish-shaped main reflector (10), and a self-supporting feed (11) for the transmission or reception of polarized electromagnetic waves. The feed (11) consists of a tube (12) which is attached to the middle of the main reflector (10) and is terminated by a subreflector (13) so that an intermediate space (14) is formed between the subreflector and the end of the tube. The part of the tube that is nearest the intermediate space (14) contains a cylindrical waveguide (15), or is the waveguide itself, and has an approximately circular or quadradic cross-section. Externally, the intermediate space (14) is bonded by a circular, cylindrical surface (16) with the same diameter as the outer diameter of the tube (12) this being called the aperture surface.

Abstract: A microwave measurement apparatus is disclosed for measuring an unknown property of a test material, such as moisture content, by transmitting microwave beams through such material so that a portion of the beam energy is absorbed by the moisture or other property. Two microwave input signals of different frequencies are used to form the microwave beams and the corresponding attenuated received signals are compared in order to compensate for the presence of a component in the test material, such as foundry molding sand, which is not being measured but which also absorbs microwave beam energy. To determine the density of the test material in the event of changes in such density, one of the microwave signals is used to measure the phase shift of the corresponding received signal and produce a phase shift output signal.

Abstract: A flat phased array antenna for reception of circularly polarized high frequency signals. The flat antenna array consists of a number of subarrays arranged in a matrix. In turn, each of the subarrays consist of individual antenna elements arranged in a matrix. In one embodiment, each subarray consists of four layers stacked one on top of the other. The top layer defines an array of miniature reception horns. Secured to the top layer is a second layer which constitutes the short-circuit plate of the antenna array. The short-circuit plate contains a plurality of through holes disposed about the surface of the circuit plate to permit passage of pairs of cylindrically shaped probes. The two remaining layers constitute the first power dividing layer and the second power dividing layer, respectively. Each of the layers includes transmission line waveguides.

Abstract: A process for joining first and second aluminum sheets in which the bonding surfaces of the aluminum sheets have their aluminum oxide layer replaced by a zinc layer and the zinc layers are plated with a non-alloy metal bonding material such as cadmium. The first and second aluminum sheets are then assembled and fastened together with an engaging means for holding the sheets together, and then the assembled sheets are placed in a vacuum. The sheets are subsequently heated in the vacuum thereby creating a bond of cadmium between them, removed from the vacuum, and then passivated.

Abstract: An improved biconical horn antenna having a broad azimuthal beamwidth and an asymmetrical elevation beam pattern. The antenna comprises two conical sections mounted against a grounded backplane with the tapered ends of the sections facing each other. The sections are of unequal size and have curved edges. The antenna is fed by a rectangular waveguide passing through the backplane between the tapered ends of the sections.

Abstract: A feed horn comprising a radiating portion having a circular aperture, a transition formed by progressively varying waveguide sections and a flange which provides a coupling with a rectangular waveguide is fabricated from moldable material and designed to be fixed in a support. The radiating portion of the horn is formed by a cylindrical flange having at least two concentric grooves which form two traps.

Abstract: A scanning antenna comprises a non-magnetic, electrically conductive radiation horn defining an antenna opening having a predetermined central line of focus, and at least one magnetically switchable conductive element such as a reed relay mounted to extend across the antenna opening perpendicular to and spaced from the central line of focus. A magnetic field generator such as an electromagnet is positioned to generate a magnetic field to control switching of the conductive element between its conductive and non-conductive states, and a control circuit controls operation of the magnetic field generator.

Abstract: A microwave transmit/receive terminal having an antenna and associated feed for receiving vertically and horizontally polarized signals and for transmitting a horizontally polarized signal employs a diplexer to be inserted between the feed and an orthomode coupler. The diplexer is formed of a cylindrical waveguide main body, a first port of which is coupled to the feed for receiving the orthogonally polarized receive signals and for coupling thereto the (horizontally polarized) transmit signal. A second port of the main body is coupled to the orthomode coupler for receiving the horizontally polarized signal to be transmitted and for coupling thereto the vertically polarized receive signals. A rectangular waveguide section is coupled to the cylindrical waveguide main body and forms a third port for coupling the horizontally polarized received signal away from said cylindrical waveguide main body.

Abstract: In an angle diversity receiving system, the primary and diversity signals are produced by a waveguide signal separator coupled to a single receiving antenna.The separator operates by converting selective higher order modes in the antenna into fundamental modes that will propagate in its two output waveguides. The result is a robust system that operates over a frequency band wide enough to cover both the 4 GHz and 6 GHz common carrier bands with both horizontally and vertically polarized signals, and that can use a wide variety of antennas.

Abstract: A versatile dual band satellite system includes a main conductive mounting plate member with a central opening of a predetermined size, and a KU band pick-up unit mounted in the plate to face a satellite antenna. A dielectric funnel support is mounted on the side of the mounting plate toward the antenna, and includes a central opening of the same size as that in the mounting plate, for receiving a C-band pick-up unit. The system includes appropriate microwave chokes and microwave impedance-matching structure, to improve the rejection of spurious or off-axis signals, and to maximize signal strength at the input of both the KU band and the C-band units. With the mounting openings in the main mounting member and in the dielectric funnel support being identical, full interchangeability of parts is practical, and an initial installation may include the C-band unit mounted in the mounting plate to face the antenna.

Abstract: A fin line circuit card containing a fin line slot feeds a dipole antenna ich extends a quarterwave outside the waveguide and provides an energy beam focal point at or near the open end of the waveguide. The dipole antenna thus maintains a wide and nearly constant beamwidth, low VSWR and a circular symmetric radiation pattern for use in electronic warfare direction finding and surveillance applications.

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 horn antenna arrangement comprising an H-plane sectoral horn 19 in combination with a feeder waveguide 2 in which radio-frequency energy is launched and propagated in the fundamental rectangular waveguide TE(1,0) mode and provided with a mode-converting section 25 of suitably shaped waveguide of reduced height in which the fundamental TE(1,0) rectangular type mode in, e.g. a planar arcuate input cross section 26, is smoothly and gradually converted into the fundamental TM(0,1) mode of an H-plane sectoral horn in an output cross section 30 which is cylindrically curved about the z axis forming the central axis of sectoral flare for the horn 19, substantially without generating any higher horn modes.

Abstract: An electrically-conductive flexible probe is mounted within a wave guide that receives radio-frequency electromagnetic radiation. A leading portion of the probe has an orientation that is adjustable between two positions that are angularly displaced with respect to each other by 90.degree.. A permanent bar magnet is connected to the leading portion of probe, and an electromagnet is mounted adjacent to the bar magnet so as to be capable of being magnetically coupled to the bar magnet.

Abstract: A horn antenna for radiating or receiving a microwave is provided with a plurality of axially spaced radial fins fixedly mounted on the outer surface of the horn, which fins form a plurality of radial grooves and a front axial groove each having a depth of approximately equal to a quarter of a wavelength of the microwave. Those fins and grooves form a choke surface-wave structure which improves the radiation pattern and reduces undesired radiation and side lobe. A multimode horn arrangement for a higher frequency wave is employed for the horn so that two different frequency waves are efficiently radiated or received at a single horn antenna with a reduced side lobe and an excellent cross polarization characteristic.

Abstract: A microwave receiving device of this invention includes a primary radiator and a low-noise converter arranged integrally therewith. One end of a chassis of the microwave receiving device is connected to a flange having an opening shape designed to provide a predetermined directivity characteristics. A waveguide as a primary radiator having a circular cross section is arranged along substantially the entire length of the chassis. A circularly polarized wave generator is arranged in the waveguide to convert a circularly polarized wave propagating through the waveguide into a vertically polarized wave. The vertically polarized wave converted by the circularly polarized wave generator is converted into an electrical signal by a probe. The probe is connected to microwave circuit boards mounted in the chassis. A microwave circuit serving as a low-noise converter is formed on the circuit boards. The electrical signal from the probe is processed by the microwave circuit formed on the circuit boards.

Abstract: A feed horn employing a novel compensator design which substantially reduces off-axis cross polarized components of circularly polarized energy over a wide range of angular directions. The compensator comprises a plurality of L-shaped compensating conductors disposed in a generally symmetrical fashion about a longitudinal axis of the feed horn. The conductors extend inwardly from the output aperture of the feed horn and then radially outwards a predetermined distance away from the axis toward the horn sidewall. The conductors are disposed at an angle relative to the axis, which angle is generally defined by an cone whose apex is the same as the apex of the feed horn. A nonconducting support structure supports the conductors within the feed horn. A dielectric matching member is disposed in the feed horn to eliminate unwanted energy reflections.

Abstract: Methods and apparatus for determining operating parameters, such as rain margin, of an antenna by attenuating the received signal by, for example, the use of calibrated attenuation pads, the method comprising placing such pads in front of the horn of the antenna feed until impulses appear on the screen of a T.V. or monitor connected to the antenna. The antenna alignment is peaked by determining the orientation of the antenna that yields the minimum impulses. The rain or impulse noise margin is determined by summing the attenuation factors of the pads with the increase in delta G/T due to the attenuation. The tuning of the receiver can be checked by observing the number of black and white impulses. The positioning of the antenna with respect to the polarization of the signal can be checked by determining the rotational position of the feedhorn which yields the minimum number of impulses. The descrambler dropout margin and clear sky carrier-to-noise ratio are determined by the addition of proper constants.

Abstract: An integrated circuit antenna structure for transmitting or receiving millimeter and/or submillimeter wave radiation having an antenna relatively unimpaired by the antenna mounting arrangment is disclosed herein. The antenna structure of the present invention includes a horn disposed on a substrate for focusing electromagnetic energy with respect to an antenna. The antenna is suspended relative to the horn to receive or transmit the electromagnetic energy focused thereby.

Abstract: Circular open ended waveguide feeds for compact ranges. Feeds according to the present invention employ smaller apertures for a given frequency of operation than a standard compact range feed. According to a first embodiment of the invention, a circular open ended waveguide feed is constructed to operate with its lowest desired frequency of operation at approximately 1.01 times the cutoff frequency. A second embodiment includes a circular open-ended waveguide loaded with ridges to lower the cutoff frequency further and thus further reduce aperture size for a given bandwidth to radiate a broader beamwidth.

Abstract: A nearly square waveguide below cutoff has a microstrip substrate disposed diagonally therein. A first shunt capacitance is provided by either a conductor formed on the microstrip substrate or a conductor disposed in the waveguide perpendicular to the microstrip substrate. A dielectric window is disposed in the end to provide a shunt capacitance at the opposite end of the waveguide.

Abstract: A fast-flared horn antenna for use in a microwave detector comprises an upwardly flared top wall, a downwardly flared bottom wall, and outwardly flared side walls extending between the top wall and the bottom wall. The curvature and the first derivative of the curvature of the flares of the top, bottom and side walls are continuous. Flared and vanishing first and second ridges are formed into the bottom wall and the top wall respectively, the curvature and the first derivative of the curvature of the flares of the first and second ridges are also continuous and sized such that the first and second ridges vanish into the bottom and top walls and the side walls at the same plane. The horn antenna may be sized such that the ridges vanish at the front edge of the aperture of the horn antenna or the ridges may vanish within the horn antenna.

Abstract: Multi-element microwave plane antenna formed from at least two metallic sheets (156, 157) on which separating studs (4, 19) are silk-screen printed and on which is inserted at least one block (50) of waveguides (2). The assembly of two such sheets forms a sandwich enclosing a printed circuit (195) carrying microwave lines which emerge into the waveguide.

Abstract: A directive communications antenna comprising upper and lower plates, each having a leading edge, and a parabolic reflecting cylinder disposed between and axially intersecting the plates so as to form a cavity having a focus line. The cavity is open adjacent the plate leading edges. Upper and lower lip plates respectively extend along the leading edges of the upper and lower plates with both lip plates projecting upwardly therefrom. A feed assembly comprised of a feed probe and a sub-reflector is positioned within the cavity.

Abstract: A hybrid-mode feed horn for feeding a reflector from the primary focus has a flange provided with grooves in an inner funnel-shaped surface thereof. The horn flange is formed to enable illumination of deep reflectors with a high aperture efficiency, low spill-over and high sidelobe suppression. The half opening angle .theta.o of the horn flange (7) is specified in the region 70.degree.<.theta.o<80.degree.. An offset of the feeding waveguide (3) in relation to the horn throat plane (21) is adjustable.

Abstract: A radar antenna element comprises a lower band waveguide and an array of parallel, dual-polarized, higher band waveguides and dipoles mounted within or directly adjacent an aperture of the lower band waveguide. The lower band waveguide and each higher band waveguide have one cross-sectional dimension less than 0.5 wavelength. A choke section, tuned dielectric or absorber isolates signals of the higher band waveguides from signals of the lower band waveguide. An array of such radar antenna elements locates a radar target with lower band signals and tracks that target with higher band signals, for instance.

Abstract: An array antenna is shown, the disclosed antenna having an effective cross-sectional area which is lower than its physical cross-sectional area. The reduction in effective cross-sectional area is effected by: (a) fabricating the reflector for the array antenna from spaced wires; and, (b) curving the entire array and its reflector.

Abstract: A feedhorn for a satellite dish which is far more efficient picking up the transmitted microwave signal from a satellite so as to permit the satellite dish to be substantially decreased in physical size. The feedhorn is constructed to pick up either the C-Band or the Ku-Band, each in either the horizontally polarized mode or the vertically polarized mode. The feedhorn utilizes dipoles for picking up the microwave signal which are then transmitted by a coaxial cable to a printed circuit board assembly. The received signal from the printed circuit board assembly is then transmitted through a receiver. The selection of the particular band of frequency that is to be transmitted from the feedhorn and the selection of the horizontal mode or the vertical mode is to be accomplished by a remote actuator such as is commonly used with a conventional television receiver.

Abstract: An electric wave operating device for efficiently coupling electromagnetic energy from a waveguide into a dielectric element or vice versa. A waveguide horn portion is chosen for radiating in the primary HE.sub.11 mode and designed to have a predetermined HE.sub.11 mode farfield radiation pattern. A dielectric member is securely disposed with one end in the plane of the aperture of the waveguide horn with the dielectric member having a predetermined HE.sub.11 mode farfield radiation pattern substantially equal to the farfield radiation pattern of the horn.

Abstract: Multi-element microwave plane antenna for receiving satellite television signals with two simultaneous polarizations. The antenna is provided with two systems of lines (1) whose ends (3, 30) form probes emerging into wave-guides (2). The probes of one system (3) are perpendicular to those of the other system (30). Between the two systems of lines there is placed only a thin sheet (150) bored with cross-shaped cut-outs (6), and provided with separating studs made from a silk-screen-printed insulating material.

Abstract: A drive system for a twistable septum in a feedhorn for use in satellite communications antenna systems. The drive system includes a flexible drive rod, coupled to a drive motor, which bends to accommodate off-center coupling with the septum drive wheel.

Abstract: The invention comprises a switching mechanism for a micro wave signal dish receiver apparatus. The mechanism has means for switching a wave guide of a 12 GHZ frequency signal into and out of concentric alignment with the center of a 4 GHZ wave guide of the apparatus. The 12 GHZ wave guide when switched out of alignment is retracted so as not to interfere with the 4 GHZ wave guide while the 4 GHZ wave guide is made operative to receive a signal of that frequency. The mechanism can project the 12 GHZ guide into the center of the 4 GHZ wave guide to receive a signal of a 12 GHZ frequency at the same focal point substantially as the focal point of the 4 GHZ, without the 4 GHZ wave guide interfering with the 12 GHZ wave guide operation.

Abstract: A planar microwave antenna of the suspended line feed type has a substrate sandwiched between a pair of conductive plates, each of the plates having aligned openings defining radiation elements. The substrate is held in place by holding portions surrounding the openings and wide grooves between the openings house a plurality of parallel suspended lines.

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.