Self-phasing antenna array techniques for mobile communications applications

This paper provides a summary of the basic concepts of retrodirective anten na arrays. Originally this class of antenna was developed in the 1960s for direct satellite-to-ground transmission of high-power microwave energy. The recent explosive growth of mobile communications has, in the authors' opin ion, reopened the debate for alternative applications of retrodirective arr ay techniques. Advances in microstrip antenna design coupled with the avail ability of integrated circuit amplifier and mixer components permit minimum -complexity retrodirective antenna arrays to be constructed. Several differ ent planar retrodirective antenna architectures are presented and their bas ic operational characteristics given. A novel application for co-operating retrodirective antennas in a duplex communication link with inherent space division multiple access capability is also described. Finally some of the operational parameters which could ultimately limit the performance of this class of antenna are discussed.