Self-phased re-transmitting integrated mixer antenna array

This paper describes a retrodirective array which employs a heterodyne phas ing technique. The array is based on the compact two-port integrated mixer active antenna element with low cross polarization, high two-port circuit i solation and good mixer detection sensitivity, arranged so to provide the c onjugate phase shift necessary for retro-direction. When driven by a refere nce signal at twice the incident frequency, the integrated mixer antenna el ements received and reradiated signals have induced a conjugate phase shift onto them. The result is retrodirective radiation that is not critically d ependent on either the array geometry or the planarity of the wavefront. Th is makes conformal retrodirective arrays possible. The physical realization of these concepts has been very much simplified using active antenna integ ration techniques by the creation of a useful general purpose two-port micr ostrip patch antenna. The two-port integral mixer antenna element realized can be used as a quasi-isolator allowing retro-direction transmitter action to be realized over a limited return angle. The experimental verification of the basic principle and performance of the retrodirective array based on this integral mixer antenna element are discussed.