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 fixed feed dual reflector scanning antenna system 10 having a low moment of inertia is disclosed herein. The inventive dual reflector antenna system 10 includes an antenna feed structure 16 for emitting electromagnetic radiation. The antenna system 10 further includes a subreflector 12 for redirecting the emitted radiation. The subreflector 12 is intersected by a subreflector longitudinal axis L.sub.s at a rotation point proximate a vertex 20 of the subreflector 12. A main antenna reflector 14 circumscribing a main longitudinal axis L.sub.m projects radiation redirected by the subreflector 12 as an antenna beam. A mechanical arrangement 22 rotates the subreflector 12 about the rotation point so as to vary the angular orientation between the subreflector longitudinal axis L.sub.s and the main longitudinal axis L.sub.m. In this manner the antenna beam is scanned relative to the main longitudinal axis L.sub.m.

Abstract: In a reflective angle of a radar, auxiliary elementary sources are positioned beneath the main source. By the division of the measurement signals of the measurement channel of the main source and of the auxiliary measurement channel, a monotonous characteristic is obtained, enabling the elevation angle to be measured with high precision. FIG. 1.

Abstract: A multibeam antenna system in which an antenna aperture element is deliberately selected to produce a divergent beam at a desired angular beamwidth. The antenna aperture may, for example, take the form of a hyperboloid reflector, a diverging lens, or a defocused paraboloid reflector. For the divergent secondary beams produced in these configurations, the angular beamwidth may be conveniently controlled by varying the mangification of the aperture or the degree of defocusing, without significantly affecting the gain or efficiency of the system. The degree of beam overlap may be independently controlled by scaling the size of the aperture, without significantly affecting the beamwidth, the gain or the efficiency.

Abstract: A reflector antenna is constructed for operation in at least two frequency ranges. For this purpose the concave surface of the antenna reflector body, which preferably has a paraboloid configuration, is provided with surface zones arranged in regular arrays or patterns. These surface zones provide antenna or reflector elements which are reflecting or transparent with regard to a particular frequency range or band width, while other surface zones of the antenna reflector surface are transparent or reflecting in another given frequency range or band widths. Thus, depending on the configurations and dimensions of these different surface zones one and the same antenna is capable of handling frequencies in a plurality of different band widths and different apertures.

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 multi-reflector antenna is disclosed which is arranged so that a main reflector surface, a subreflector surface and a primary radiator are electro-magnetically coupled together. When the main reflector is represented by a coordinate z=z(.rho., .psi.) using cylindrical coordinate system (z, .rho., .psi.) in which the direction of radiation of a main beam of the main reflector surface is in correspondence with the z-axis and the subreflector surface is represented by a coordinate r=r(.theta., .phi.) in a vector system using a spherical coordinate system (r, .theta., .phi.) in which the Snell's reference direction of the primary radiator is set to .theta.=0, the said z(.rho., .psi.) and r(.theta., .phi.) are so determined as to satisfy the law of reflection, a condition of constant path length and the following relation:.psi.=-.phi.+.psi..sub.0.rho.=.rho..sub.0 tan.theta./2where .psi..sub.0 and .rho..sub.0 are constants. The primary radiator is comprised of a plurality of horns.

Abstract: A reconfigurable beam antenna system (12) comprises focusing means, a plurality of antenna elements (A, B, C, and D), a feed network (14), and a variable beam controlling means (16). The focusing means has a reflecting surface (18) which is adapted to reflect a plurality of electromagnetic energy signals. The feed network (14) comprises a plurality of feed ports (I1, I2, I3, and I4), a first plurality of hybrid couplers (30 and 32) connected to the feed ports, a plurality of phase shifters (34 and 36) connected to the first plurality of hybrid couplers, a second plurality of hybrid couplers 38 and 40 connected to both the first plurality of hybrid couplers and the phase shifters, and a plurality of antenna ports (01, 02, 03 and 04) connected to both the second plurality of hybrid couplers and the antenna elements (A, B, C, and D).

Abstract: A satellite communications system employs separate subsystems for providing broadcast and point-to-point two-way communications using the same assigned frequency band. The broadcast and point-to-point subsystems employ an integrated satellite antenna system which uses a common reflector (12). The point-to-point subsystem achieves increased communication capacity through the reuse of the assigned frequency band over multiple, contiguous zones (32, 34, 36, 38) covering the area of the earth to be serviced. Small aperture terminals in the zones are serviced by a plurality of high gain downlink fan beams (29) steered in the east-west direction by frequency address. A special beam-forming network (98) provides in conjunction with an array antenna (20) the multiple zone frequency address function. The satellite (10) employs a filter interconnection matrix (90) for connecting earth terminals in different zones in a manner which permits multiple reuse of the entire band of assigned frequencies.

Abstract: A frequency selective screen (18) is employed as a diplexer to separate each of one or more radio frequency signals into first and second bands of frequencies by allowing the first band of frequencies to pass therethrough and reflecting the second band of frequencies. The screen (18) includes an array of discrete, electrically conductive elements (32), preferably copper, formed on a substrate (33) such as a layer of polyimide. The conductive elements (32) possess a geometry which results in an equivalent electrical circuit (50) that exhibits parallel resonance, high impedance within the first band of frequencies and series resonance, low impedance within the second band of frequencies, thereby transmitting the signal in the first frequency band and reflecting the signal in the second frequency band.

Abstract: An angular-diversity radiating system is described for tropospheric-scatter radio links which accomplishes a symmetrical Cassegrain optic in transmission and is parabolic with a central focus in reception, respectively. This is accomplished by a subreflector formed of parallel metal conductors and shaped with a hyperbolic profile which is centered on the axis of the main reflector at a predetermined distance between the transmitting horn and the receiving horns. The electromagnetic waves leaving the transmitting horn and directed toward the subreflector are polarized with the electric field vector parallel to the metal conductors of the subreflector such as to be reflected toward the main reflector which reradiates them. The electromagnetic waves received are polarized orthogonally to the transmitted waves and thus pass undisturbed through the subreflector to reach the receiving horns.

Abstract: A steerable multibeam five element cross-feed cluster antenna (16) system. The feed power is divided into five branches. Each branch includes a switching network (12A-12E) comprised of a plurality of time delay elements (90A; 92A) each individually controlled by a respective electromagnetic latching switch (56A,B; 58A,B; 60A,B; 62A,B; 46A,B). Frequency independent individual two-dimensional beam steering at IF scanning frequencies is thereby provided wherein discrete incremental time delays are introduced by the switching networks into each branch and the signals recombined thereafter to form each beam. The electromagnetic latched switching reduces power consumption and permits higher power switching and reciprocal coincident transmit and receive operation. Frequency independence due to incremental time delay switching permits coincident reciprocal operation and steering for transmit-receive signal paths carrying different transmit-receive frequencies.

Abstract: An antenna system includes a reflector which is a part of a paraboloid of revolution or parabolic cylinder, a primary radiator for clockwise circularly polarized wave, and a primary radiator for counterclockwise circularly polarized wave. The reflector is of geometrically asymmetrical shape to effect different reflection properties for clockwise and counterclockwise circular polarizations. The primary radiators are fixed at two different positions in the vicinity of the focus of the paraboloid reflector.

Abstract: An antenna feed structure for use with a parabolic reflector in amplitude-comparison monopulse radar applications employs a dedicated transmit feed centered within a four-port receive array of conventional element spacing to eliminate the need for a circulator or other transmit/receive device while retaining satisfactory receive array performance. Isolation pins placed around the transmit port act to decouple it from the receive ports, and a double waveguide run to the transmit port reduces uneven heating and related phase imbalance in adjacent receive waveguide runs.

Abstract: The invention provides an antenna for transmitting or receiving closely spaced multibeams with very low level sidelobes comprising, for each beam feed, a primary feed feeding one or more main elements surrounded by secondary elements some of which are shared between several adjacent beam feed, the power supplied by the primary feed being distributed to the different elements by means of couplers. According to the invention, each shared element is fed by each of the power transmission lines feeding the main element (E1, E'1) of said adjacent beams through a coupler, each transmission line of a secondary radiating element (L2, L'3) comprising at least two couplers (C1, C2) in series.

Abstract: An apparatus and a method for achieving simultaneous circular polarization of a four-beam doppler antenna wherein four different grid layers are positioned into a radome. The first grid layer, besides radiating a linear polarized beam, is used to partially reduce contaminants of the linearly polarized beam by means of cross-hatch strips. The second grid layer is used to further purify the linear polarized beam such that an essentially purified linear polarized beam is obtained. The third grid layer, designed according to certain equations, is used to convert the purified linearly polarized beam into a partially circularly polarized beam. And the fourth grid layer is used to make sure that the circularly polarized beam is perfectly matched.

Abstract: A reflector antenna is disclosed which generates two or more beams which are separated angularly in the elevation plane, as in multi-beam antennas, and are shaped so as to provide, when combined, any desired pattern of coverage. The antenna includes a horn which receives separated inputs and radiates toward a reflector primary beams displaced from one another by a predetermined angle but having a single phase center.

Abstract: The isolation of mainbeam and sidelobe jamming signals from the desired signal being relayed by microwave communication links is accomplished by an antijamming antenna comprising a flat radome, a curved reflector and a transmit dipole. Positioned adjacent the dipole is a monopulse feed and comparator for main-beam jammers (dual-plane monopulse, multi-mode multilayer feed). Also forming part of the integrated antenna are auxiliary units for near-sidelobe and far-sidelobe jammers. An alternative embodiment includes a Cassegrain grating sub-reflector. Since the direction of the desired incoming signal in microwave communication links is precisely known, the antijamming antenna uses azimuth and elevation monopulse to make a spatial distinction between the desired incoming signal and the jamming signals.

Abstract: The present invention relates to an antenna arrangement for correcting for astigmatism is a beam which is linearly scannable in a first principal plane of the antenna arrangement. The antenna arrangement comprises a parabolic or torus main reflector and a feed arrangement for producing first and second astigmatic phase centers which lie along first and second focal lines, respectively, in the first principal plane and match first and second astigmatic phase centers required by the main reflector to produce a linearly scannable plane wave.

Abstract: An aperture transformation sidelobe canceller includes a plurality of auxiliary feed elements disposed in the vicinity of, but critically offset from, a main feed horn. The signal paths for the auxiliary feed horns are coupled through a low loss cascade RF variable direction coupler network to be combined with the RF signal path for the main antenna feed. The combined signal path is coupled to a performance monitoring processor which, in turn, adjusts the coupling action of each variable directional coupler to achieve the necessary weighting and combining of the auxiliary feed signal paths. The critically offset auxiliary feed elements provide the capability of achieving very broadband and deep nulls from the simple variable directional coupler network. The null availability makes it possible to null the entirety of the main elements sidelobe region, including backlobe and even the first sidelobe region of the antenna pattern, as the offset auxiliary feed horns provide substantial coverage in this region.

Abstract: An antenna system in which primary radiators are disposed on the radiation side of beams from a main reflector and in opposition to a subreflector and in which the subreflector and the primary radiators are disposed in positions offset from beam blocking positions.

Abstract: This invention relates to a multi-beam antenna and a method of configuring the same, where the antenna consists of a main reflector, a plurality of horns for exciting the main reflector, and separate sub-reflectors for correcting phase errors of respective beams caused by reflection at the main reflector, or an integrated sub-reflector which is substituted for said separated sub-reflectors.

Abstract: The present invention is directed to a multibeam antenna reflector distortion compensation system comprising at least one remote reference radio frequency transmitter cooperating with a feed cluster of a beam forming network which includes one central and at least two peripheral feed elements, means for producing error signals including a circuit for consecutively connecting each peripheral cluster feed element to one input of an adding circuit, and the central feed element to the other input after appropriate attenuation and phase compensation of the central feed signal, and means for down-converting linear and non-linear distortion correction signals based on the down-converter output.

Abstract: This invention relates to an antenna system for a jamming transmitter which is intended to protect a remote object which is remote from the jamming transmitter as well as itself or an object in the immediate vicinity of the jamming transmitter. Known jammer antennas for this purpose radiate either a pencil beam which presents considerable problems in the alignment and orientation and tracking in two planes or alternatively such known antennas are designed as omni directional antenna which however have low antenna gain and are easily detected. In the present invention the difficulties of the prior art are eliminated in that a separate antenna is provided for external or foreign protection and a separate antenna for self protection which antennas produced in the first plane a sharply focused pattern and in a plane perpendicular thereto a radiation pattern (7, 8) which is optimized for external or foreign protection or self protection, respectively.

Abstract: A reflector type radio frequency antenna having: a feed for producing a difference radiation pattern with a cone-shaped null region; and, a reflector having a surface disposed to reflect a portion of the energy in the difference radiation pattern and having the edge disposed in the cone-shaped null region. With such arrangement, since the edge of the reflector is disposed in the null region of the difference radiation pattern such edge is not radiated with energy which could otherwise illuminate such edge, scatter, and thereby generate unwanted side lobes in the free space antenna pattern.

Abstract: The present invention relates to a multibeam antenna arrangement having minimal primary aberration of astigmatism and coma over a wide area of the focal surface of the antenna. The present antenna comprises a plurality of N reflectors arranged confocally in a sequence along a feed axis of the antenna and at least one feed disposed in the vicinity of a focal point on the focal surface. The reflectors and the at least one feed are further arranged to provide an equivalent centered antenna arrangement with the longitudinal axis of the feed substantially parallel to an equivalent axis of the centered arrangement for eliminating astigmatism. Primary coma is then eliminated by deforming two of the N reflectors in a predetermined manner.

Abstract: The present invention relates to antennas with a segmented reflecting surface for providing fully or partially overlapping beams from separate feeds associated with each segment without incurring cross-coupling between feeds and power loss. More particularly, a main reflector or a subreflector reflecting surface is segmented to provide separate images of the far field area of the antenna on separate focal surfaces in the vicinity of an original focal surface of a corresponding non-segmented antenna. Feeds disposed at essentially corresponding locations on each of the far field area images produced by each of the segments provide separate beam footprints which overlap each other in the far field area by a predetermined amount.

Abstract: An antenna having a frequency separator of the type comprising plural lattice structures of a periodic conductive pattern. Each lattice structure exhibits an inherent resonance frequency and an inductance-capacitance effect at frequencies below the inherent resonance frequency. The periodic conductive patterns are selected so that each of the lattice structures exhibits substantially the same inherent resonance frequency, and when placed at selected intervals, the plurality of lattice structures exhibit interactive resonance at frequencies below the inherent resonance frequencies. Each lattice also exhibits substantially equal inductance and capacitance with respect to obliquely incident electromagnetic waves in the TE and TM modes.

Abstract: A dual band mirror antenna employing a continuous mirror without a hole. e-by-side feeds for each band and an electromagnetic lens, located behind a rotatable twist reflector (the mirror), collimate beams toward a pair of polarized reflectors located near the twist reflector and tilted to aim the reflected energy toward the twist reflector. One polarized reflector is reflective at the higher radiofrequency band and transparent at the lower radiofrequency band. The other polarized reflector is reflective at both bands. Energy directed back toward the polarized reflectors from the twist reflector passes through the polarized reflectors to free space.

Abstract: Disclosed is an antenna device, which comprises a reflector and a primary radiator for an ARSR system including a low beam horn antenna disposed at a position substantially at the focal point of the reflector and a high beam horn antenna disposed below the low beam horn antenna. The antenna device further comprises a primary radiator for an SSR system including two modified diagonal horns provided on opposite sides of and having outside perimeters complementary to the arrangement of the low and high beam horn antennas and at positions corresponding to a position midway between the low and high beam horn antennas. A Yagi antenna used as a part of the SSR radiator, is disposed above the low beam horn antenna. Thus, the antenna device can be used commonly for both the ARSR and SSR systems.

Abstract: The present invention relates to a feed arrangement for use with compact scanning beam antennas which comprises a linear phased array of small feed elements (10) which form an approximate line source that radiates a wedge-shaped cylindrical beam toward a subreflector (12) which is shaped to focus the wedge-shaped cylindrical beam to a point source which then produces a spherical wavefront. The spherical wavefront can then be focused by a main reflector (14) into linear scanning beams if desired. Multiple linear phased arrays of small feed elements can be disposed parallel to each other to form a multibeam feed arrangement for producing multiple fixed or scanning spot beams.

Abstract: A radar antenna includes a box horn radiator which is capable of simultaneously transmitting X band and S band signals. The S band signals are transmitted as a resultant of the TE.sub.01 and TE.sub.03 mode, which is generated within the box horn. Additionally, the X band frequencies are fed into an off-set input port, which launches the X band signal as a surface wave. By positioning the box horn at the focus of a reflector, azimuth pointing errors are prevented but different elevation patterns are produced.

Abstract: The present invention relates to a low power, beam switchable, antenna comprising a focusing reflector (14), a plurality of feedhorns (10.sub.1 -10.sub.N) disposed on a surface (.SIGMA.) adjacent the focal surface of the focusing reflector, and an amplifying array (20, 24, 28) disposed in the aperture of the focusing reflector. A spherical wavefront launched by a feedhorn is reflected by the focusing reflector into a first planar wavefront which is intercepted by the amplifying array using a planar array of first feed elements (20.sub.1 -20.sub.X) disposed on a fourier transform surface (.SIGMA.') of the surface on which the feedhorns are disposed. The signal produced by each of the first feed elements associated with a first planar wavefront is separately amplified with an equal relative phase shift to the other associated intercepted signals and reradiated in a second planar wavefront by a planar array of second feed elements (28.sub.1 -28.sub.

Abstract: The present invention relates to a dual polarized feed by which two linea polarized waves can be reliably separated. The two waves are conducted separately over high frequency coaxial cables, one of which extends axially and the other radially into the polarizer. Rotation of the planes of polarization is thus unnecessary and the two cables have a minimum influence on the illumination (irradiation) of the reflector.

Abstract: The crosspolarization components radiated by adjacent orthogonally linearly polarized feed horns of a reflector antenna system are compensated by structural modifications incorporated in the feed horns. In a first embodiment, the modified feed horns have curved walls and included shaped septa. Other embodiments involve the use of shaped walls or shaped septa only. In the case of an offset reflector, asymmetric modifications of the wall shape and septa are employed. For flared feed horns with rectangular cross section, the crosspolarization compensation is provided by curving the forward edges of the horn walls convexly or concavely as required.

Abstract: The present invention relates to a wide-field-of-view antenna arrangement which permits the angular range over which multiple beams may be transmitted or received to be increased by taking into consideration the location of the tangential and sagittal focal regions associated with multibeam systems. The subreflector (18,24) is positioned relative to the main reflector (10,20) such that the tangential and sagittal focal regions lie behind the subreflector of a Cassegrainian arrangement, or alternatively in front of the subreflector of a Gregorian arrangement for a predetermined wide-field-of-view.

Abstract: An antenna arrangement for a radar surveillance method for target locating having altitude acquisition provides that, for the purpose of level comparison, a plurality of overlapping lobes lying above one another are generated by a reflector rotating around a vertical axis together with a primary radiator row arranged essentially vertically. In employing a paraboloid of revolution as the reflector, a vertical primary radiator row is arranged around its focal point. Given more greatly deflected beams whose exciters are at a greater distance from the focal point, the gain in such an antenna decreases as the side lobes increase, limiting the elevation angle range. A single parabolic cylinder reflector generating a beam and focusing only in the horizontal plane is employed as the reflector, the individual radiators of a primary radiator row being arranged along its focal line.

Abstract: The antenna system employs a parabolic reflector fed by an offset feed array of circular wave guides located substantially at the focus of the parabolic reflector, but offset from the axis thereof. A plurality of aperture tuning mechanisms disposed at the mouths of the circular waveguides of the waveguide feed array, and having physical lengths much shorter than one wavelength at the frequencies involved, are provided to reduce cross-polarization and mutual coupling between adjacent feeds. The short resonant length of these tuning mechanisms, and their shape which is chosen to generate the TM.sub.11 mode E-field contour line ensures that they are effective over a broad bandwidth of as much as 20% or more. Within this bandwidth, they act as inductive suppressors to control both cross-polarization and mutual coupling between adjacent feeds.

Abstract: A triple-beam offset paraboloidal antenna minimizes the offset of each of ree antenna feeds from the focal point of the paraboloid to thereby minimize beam aberrations, while at the same time maximizing the beam steering capability of the antenna. Three beams are produced, two being in mutually orthogonal planes. The axis of the third beam corresponds to the intersection of the orthogonal planes. The antenna in accordance with the present invention finds particular utility in the measurement of three dimensional wind profiles employing doppler radar techniques.

Abstract: A dual-band antenna for the transmission and reception of radiant energy has a Cassegrain-type reflector assembly, rotatable about an azimuth axis and pivotable about an elevational axis, to which two outgoing beams are directed in a transmitting mode by a periscopic supply system including a set of four mirrors, two of them flat and two of them concave. The lower-band beam originates at a first feed comprising a horizontally radiating horn and two confronting concave mirrors, one of these mirrors training the beam onto a slanting dichroic mirror reflecting same upward into the periscopic supply system. The higher-band beam originates at a second feed also comprising a horizontal horn which radiates onto a concave mirror reflecting the beam upward through the dichroic mirror into the periscopic supply system along a path coinciding with that of the other beam.

Abstract: The present invention relates to an antenna arrangement capable of generating one or more linearly scanning spot beams which are scanned over separate strip portions of the entire field of view of the antenna. The antenna arrangement comprises an optical system comprising an aperture and a focal plane, and a novel feed arrangement. The feed arrangement comprises a separate linear phased array disposed within a separate rectangular waveguide section for each linear scanning beam desired. An offset curved reflector, disposed in each waveguide section, converts a linearly scanning planar wavefront generated by an array into a converging beam forming a linearly moving point source on the antenna's focal plane with the principle ray of each instantaneous wavefront being directed at the center of an image of the aperture of the optical system as seen by the feed arrangement.

Abstract: A self-multiplexing antenna comprising an array of radiating elements for diating a plurality of orthogonal beams in response to wave energy excitations applied thereto. A plurality of first transmission lines are connected between respective radiating elements and respective resistive terminations. A plurality of second transmission lines are connected between respective input ports and respective resistive terminations. A plurality of directional couplers couple wave energy from each input port to each radiating element in the array via the first and second transmission lines whereby wave energy from each input port generates a separate orthogonal beam from the array of radiating elements.

Abstract: Microwave energy feed elements for launching essentially linearly polarized beams in a satellite communications system are oriented in the satellite's antenna so that the polarization directions of the feed elements form a rim and spoke configuration. The vertical polarizations are arranged to extend radially from a point on the antenna's focal surface which images the point on the surface of the celestial body directly below the satellite. Horizontal polarizations are arranged concentrically about the subsatellite image point. Electromagnetic energy launched from the feed elements will reach the surface of the earth at planes of incidence which are locally vertical and horizontal, thereby minimizing cross-polarization coupling between the orthogonally polarized signals due to such energy passing through precipitation.

Abstract: A feature of this invention is the provision of an antenna system providing two, coaxial, copolarized, independently focused beams: a relatively wide, low frequency, searching beam, and a relatively narrow, high frequency, tracking beam; and comprising a dual frequency, dual polarization feedhorn; a polarization dependent subreflector; a concave polarization reversing reflector; a concave polarization twisting reflector; and a planar frequency dependent dielectric lens.

Abstract: A dished reflector is illuminated by a primary radiation feed including a rectangular waveguide and a secondary radiation feed comprising two dipoles flanking that waveguide. In order to minimize distortion of the radiation diagram from the secondary feed by the waveguide envelope, at least one elongate corrective member paralleling the dipoles is externally mounted on that envelope and is capacitively coupled or conductively connected thereto at a location where a peripheral current induced by the dipoles is at a maximum. The corrective member, like the dipoles themselves, may be a plate with major faces lying in planes perpendicular to the waveguide axis.

Abstract: The present invention relates to antennas which have reflector arrangements that produce a large image with minimal aberrations at the exit aperture thereof of a small feed array. In the present arrangement, the feed array is placed at the conjugate plane relative to the exit aperture of a geometrically confocal reflector system comprising a parabolic main reflector and a parabolic subreflector so that exact imaging of the array is obtained at the exit aperture. In such arrangements, alignment and surface accuracy errors of the various reflectors can be easily corrected by appropriately changing the phase or the position of the associated elements of the feed array. A three-reflector arrangement having sequential geometric confocality is disclosed which also alters the focal length of the main reflector sufficiently to permit the inclusion of polarization and/or frequency diplexing means in the overall reflector system.

Abstract: An antenna assembly with a curved reflector and feed means at one side of the focal axis of such reflector. The feed means includes a number of relatively-fixed-position feed elements spaced apart unequally to obtain signals of different phase at the reflector for forming a composite reflected beam with minimized sidelobe content.

Abstract: A mechanically scanned antenna system having a multiport rotary switch for sector scanning is disclosed. The switch includes a stationary subassembly and a rotating subassembly. The stationary subassembly contains the input ports and the rotating subassembly contains the multiple output ports associated with each input port. Each of the multiple output ports of the switch is sequentially activated through its designed active sector to produce the desired antenna scan pattern. The stationary subassembly includes a barrier member which is rotatable to selectively orient and maintain orientation of the active region of the antenna system at any position through 360.degree..

Abstract: Eight radiators are disposed along a line in a vertical plane that intersects the focal point of a paraboloid reflector. When excitation is applied to a radiator, electromagnetic energy is transmitted therefrom to the reflector, thereby causing the reflector to reflect a beam at a selected elevation angle. Moreover, the beam is focused in azimuth. The beam is defocused in elevation in direct relation to its angle of elevation.

Abstract: The present invention relates to novel launcher reflectors which are used with reflector antenna systems to compensate for the dominant aberration of astigmatism which was found to be introduced in the signals being radiated and/or received at the off-axis positions. A major portion of such phase error is corrected by using, with each off-axis feedhorn, an astigmatic launcher reflector having a curvature and orientation of its two orthogonal principal planes of curvature which are chosen in accordance with specific relationships, the launcher reflector being fed by a symmetrical feedhorn.