Cavity-backed, micro-strip dipole antenna array

Claim 1

An antenna system particularly adapted for mounting flush with the skin surface of a reentrant air/space vehicle, to generate selectable sum and difference, circularly polarized radiation patterns from an aperture substantially flush with said skin surface comprising: a conductive cavity of substantially square cross-section in a plane parallel to said skin surface and of uniform depth internal to said vehicle, said cavity providing an aperture substantially at said flush mounting at said skin surface; first means within said cavity comprising a pair of dielectric boards each in a plane normal to said cavity cross-sectional plane, said boards each fitting between opposite corners of said cavity and intersecting orthogonally substantially at the center of said cavity; second means comprising a plurality of printed circuit dipoles, located two to the broad surface of each of said boards, one on either side of said board intersection; third means comprising a printed circuit feed trace on the opposite side of said dielectric board from each said dipoles, said traces each feeding a corresponding dipole through said board dielectric; fourth means comprising an external connection for each of said feeds to facilitate independent excitation control for each of said dipoles; and fifth means comprising a first four-port hybrid connected from two orthogonally adjacent dipole feeds of said third means to provide a first combined signal, a second four-port hybrid connected from the two remaining dipole feeds of said third means to produce a second combined signal, and a four-port comparator hybrid connected discretely at two of its ports to said first and second combined signals, said comparator hybrid also having Σ and Δ ports such that selective excitation of one of said Σ and Δ ports produces a corresponding antenna pattern.