Abstract: An antenna for use in propagating or receiving microwave radiation having both left-hand and right-hand circular polarization. The left-hand and right-hand circularly polarized radiation may be transmitted or received simultaneously without interference with one another, that is, they are isolated from one another by 27 dB or more. The preferred antenna comprises an array of closely clustered waveguide elements each of which converts respective linearly polarized signals to left-hand and right-hand circularly polarized signals and vice versa. Isolation means also are provided in each of the waveguide elements for preventing radiation either propagated or received by a waveguide element from being coupled into the radiation being propagated or received by other waveguide elements in the array. Preferably, square waveguide is utilized for the array elements and the isolation is provided by a plurality of conductive elements mounted on each of the open ends of the waveguide elements.

Abstract: The antenna arrangement for radar or direction finding purposes, respectively, has sum and difference patterns for mono-pulse operation comprising a reflector and at least two linearly polarized exciters located approximately in the center between which perpendicular to their polarization direction a metallic conductive plane partition is disposed which extends to the reflector and stands perpendicularly thereon, wherein the partition does not extend through the entire reflector from edge to edge but is arranged only approximately in the area of the exciters.

Abstract: An antenna element is disclosed having a printed circuit parallel plate region with a parabolically shaped reflecting wall and a flared radiating section. The flared radiating section is disposed along an aperture which intersects the axis of the parabola at an acute angle. A microstrip feed formed integrally with the printed circuit parallel plate region is offset from the reflecting wall and is adapted to introduce radio frequency energy at the focal point of such reflecting wall. Load material is disposed adjacent to the focal point to absorb radio frequency energy reflected by the aperture thereby improving the VSWR of the feed. Such arrangement enables close element-to-element spacing in an array, thereby substantially eliminating grating lobes while enabling intermeshing of the elements to provide port and starboard array antennas.

Abstract: Omnidirectional antenna provided with a rotation-symmetrical reflector and a concentric radiator, to be mounted around a mast, which radiator has an uninterrupted annular exit edge. All the diametrical cross sections of the radiator along the axis of the antenna are uniform. The path followed by the radiation in the radiator beyond the part deflecting from the axis of the antenna, is turned up in the direction of the reflector.

Abstract: A plurality of steerable beam feed devices are used in combination with a single stationary toroidal antenna which permits simultaneous communication with several geosynchronous satellites. Each feed device is movably mounted on a flat elevation plate having linear bearings which mate with rails on a flat azimuth plate to allow the feed to be positioned vertically or at some angle with respect to the vertical depending upon the orientation of the antenna. The flat azimuth plate is mounted for movement on two curved rails which follow the focal arc of the toroidal antenna. Linear actuator devices are provided for moving each plate within a limited range to provide fine positioning of the feed relative to the antenna.

Abstract: In a switchable beamwidth monopulse method and system, an antenna comprising a curved reflector and a first set of monopulse feeds positioned in the effective region of the Airy disc of the antenna includes a second set of monopulse feeds. The second set of monopulse feeds is positioned outside the Airy disc in the region of first bright Airy ring. In narrow beamwidth monopulse operation, monopulse sum and difference channel patterns are obtained from the first set of feeds within the Airy disc. In wide beamwidth monopulse operation, the difference channel pattern is obtained from the second set of feeds in the Airy ring; the sum channel pattern is obtained by attenuation and phase shifting the sum channel signal obtained from the first set of feeds, and adding the resultant to the sum channel signal obtained from the second set of feeds.

Abstract: A compact offset Cassegrainian antenna having a paraboloidal main reflector and a convex subreflector brings microwave beams to a focus. A small flat reflector placed in one of the beams at the focus deflects it for interception by a concave reflector and horn. Another beam passing by the flat reflector is intercepted by a second concave reflector and horn. The flat reflector is smaller than a focally located horn, allowing more closely-spaced beams to be accommodated. The flat reflector may be replaced by a curved reflector, a prism, or a microwave lens. Another flat reflector is added for each additional beam. Polarized beams are accommodated by adding a polarization screen.

Abstract: A multiple beam antenna having either a main reflector or a lens is illuminated by a feed system comprising a number of primary radiators such as dipole elements. Primary radiation from each dipole element reflects from the principal reflector to produce a different respective one of the multiple secondary beams in the remote field. A disk-shaped electrically conductive director is located in the primary radiation path near each primary radiator. Each director operates both to shape the primary pattern of its respective primary radiator directly, and also to excite parasitic radiation in neighboring primary radiators so as to produce a primary radiation pattern whose shape approximates a sector of a circle, thereby producing high illumination efficiency at the main reflector. The desired sector shape of primary pattern is achieved despite relatively close lateral spacing between adjacent primary radiators of the feed system.