Self-phased re-transmitting integrated mixer antenna array

Abstract

This paper describes a retrodirective array which employs a heterodyne phasing technique. The array is based on the compact two-port integrated mixer active antenna element with low cross polarization, high two-port circuit isolation and good mixer detection sensitivity, arranged so to provide the conjugate phase shift necessary for retro-direction. When driven by a reference signal at twice the incident frequency, the integrated mixer antenna elements received and reradiated signals have induced a conjugate phase shift onto them. The result is retrodirective radiation that is not critically dependent on either the array geometry or the planarity of the wavefront. This makes conformal retrodirective arrays possible. The physical realization of these concepts has been very much simpli® ed using active antenna integration techniques by the creation of a useful general purpose two-port microstrip 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 veri® cation of the basic principle and performance of the retrodirective array based on this integral mixer antenna element are discussed.