Abstract: An antenna includes a feed generating a communication signal. A sub-reflector is positioned to reflect the communication's signal to form a sub-reflective signal. A main reflector is positioned to reflect the sub-reflective signal. The sub-reflector has an elliptical rim.

Abstract: An antenna includes a feed generating a communication signal. A sub-reflector is positioned to reflect the communication's signal to form a sub-reflective signal. A main reflector is positioned to reflect the sub-reflective signal. The sub-reflector has an elliptical rim.

Abstract: A passive array of resonantly-dimensioned microstrip antenna radiator patches are closely spaced (i.e., less than one-tenth wavelength) above a ground plane and individually associated with transmission line segments terminated so as to cause the overall array to receive an incident r.f. electromagnetic field, to convert the received field into r.f. electrical currents which flow along the transmission lines and are absorbed by the terminations or reflected therefrom. In the latter case, the reflected r.f. energy is re-transmitted in a predetermined direction as a re-directed r.f. electromagnetic field. The presently preferred embodiment is a relatively thin, flexible and thus conformable layered structure formed by selectively etching conductive material from one side of a metallically cladded dielectric sheet. For satellite communication, a flat reflectarray may be associated with a primary r.f.

Abstract: First and second annular r.f. radiating structures are mounted for concentric relative rotational motion with their r.f. radiation patterns directed toward one another. The annular r.f. radiating structures may be realized, for example, by cylindrically conformed microstrip antenna radiators which define tuned resonant cavities feeding one or more radiation apertures defined between an edge of a microstrip radiator "patch" and an underlying electrical reference or ground surface. The microstrip radiator "patch" may be either continuous in its circumferential dimensions or it may have occasional circumferential discontinuities formed by axially directed gaps therein. If the total circumferential dimension is greater than one wavelength at the intended operating frequency, then a corporate structured feedline provides plural spaced-apart feedpoints about the circumference so as to achieve a substantially uniform distribution of r.f. field amplitudes and phases about the circumference.

Abstract: The wide ends of two similar horn structures are juxtaposed and joined by a rotary bearing extending thereabout which permits relative rotational motion between the two horn structures. A field shaping lens may be disposed at the relatively rotatable horn juncture to help insure substantially planar wavefront shapes across the relatively rotatable joint. An annular aperture may also be provided between the relatively rotatable horns and electrically loaded so as to present an approximate short circuit electrical impedance at the intended frequency of operation.