Phased array antenna system using polarization phase shifting

Abstract

A circularly polarized phased array antenna system for both reception and transmission applications includes a plurality of planar radiating (or receiving) elements, a switching matrix for each radiating element, a beamforming network and a transmit/receive module. Each planar element includes 4.times.N radially disposed segments that may be selectively connected with the four modes of a circularly polarized signal such that two opposing segments function as the two respective arms of a dipole radiating element and two orthogonal such dipoles function as a crossed pair of dipoles for receiving or transmitting the circularly polarized signal. The switching matrix and the beamforming network cooperate to determine the polarization phase of the radiating element by commutating the four modes of the circularly polarized signal to any four orthogonal segments of the radiating element. The polarization sense may be changed between right-hand and left-hand circular either within the bandforming network, or by causing the switching network to reverse the two signal modes connected across one of the dipoles. If N is greater than 1, then by electrically connecting up to N-1 nearby segments to thereby increase the effective angle subtended by each arm, the bandwidth may be increased while still permitting the radiating element's polarization phase to be determined in increments equal to the angle subtended by one segment; by selectively using either an odd or even number of segments to define the effective angle subtended by each dipole arm, the relative phase of that element may be determined in increments equal to half the angle subtended by one segment.

Dependencies are inferred from the claim text.