Abstract: A composite antenna for use in satellite communication provides both the functions of multiple beams and a shaped beam radiated from a single radiating aperture. The radiating aperture may employ a mirror or a lens. Transmitted radiation from an array of radiators is coupled via a subreflector to the main reflector or lens which constitutes the radiating aperture of the antenna system. During reception of radiant-energy signals, signals received by the main reflector or lens are coupled via a separate subreflector to a separate array of receiving radiators operated at a frequency band different from that of the transmit array. The two subreflectors are combined into a single subreflector assembly employing a metallic concave reflector covered by a layer or coating of frequency selective optical material which allows for propagation of radiation at one frequency to the metal reflector while reflecting radiation in the other frequency band from a surface of the coating.

Abstract: An antenna has one feed for an S-band electromagnetic signal, and a second feed constructed as an array of radiators to service two C-band signal channels. A subreflector having a microwave frequency selective surface (FSS) is placed in front of a main reflector. The C-band feed is constructed of an array of square aperture horns joined by separate transmit and receive barline beam-forming networks, and a meanderline polarizer to produce circularly polarized radiation patterns. Tapered ridges extend longitudinally along inner wall surfaces of each of the horns to provide increased bandwidth to the C-band feed. The frequency selective surface is constructed, typically, of a generally planar substrate of material transparent to electromagnetic radiation, and numerous metallic, generally annular, radiating elements, or resonators, arranged on the substrate in an array of repeating nested sets of the radiating elements.

Abstract: An antenna composed of an array of helical radiators has, in accordance with a methodology of the invention, a physical structure for reducing mutual coupling between closely spaced radiators so as to permit a reduction in spacing of the radiators. The radiators are mounted upon a mounting base, such as a ground plane element, with the helical radiators extending forward of the mounting base. Distances between the radiators and the mounting base are staggered in an amount approximately equal to one turn of a helix. The stagger distance corresponds approximately to one quarter of a free-space wavelength. The staggering significantly reduces the mutual coupling so as to permit closer spacing of the helical radiators such as, by way of example, in the formation of a feed directing radiant energy to a reflector of the antenna.

Abstract: The EHF omnidirectional antenna system (10) includes a shaped lens (12) that is illuminated by a corrugated horn (14). The lens is disposed in the far-field of the horn and has two shaped surfaces (20 and 30) which together disperse the beam from the horn, such that a nearly uniform coverage over hemispherical coverage area is achieved at a frequency of approximately 44 GHz. The method of making the lens utilizes a surface shaping analysis to develop the shaped surfaces of the lens. A surface matching layer (44) is applied to all surfaces of the lens to reduce surface reflection.