Self-Steering Arrays For Wireless Communication Networks

Abstract

A Retrodirective array has the unique property in that when it is interrogated, the array automatically points its beam toward the interrogator. Unlike more complicated arrays that require digital signal processing, the retrodirective array achieves self-steering through simple analog circuits. As a result, retrodirective arrays are the preferred solution for applications requiring self-steering where the limiting factors are cost and design complexity. This thesis presents several advances in wireless communications systems through the use of retrodirective arrays. First, a phase-conjugating retrodirective array is used to improve the reliability of a radio link in a severe multipath environment. The method showed up to 31 dB of improvement of a 5.35-GHz communication system when compared to a conventional array. Next, for terrestrial-to-space or space-to-space applications, a two-dimensional retrodirective array is presented at 3.84 GHz. The complexity of a complicated LO feed network is eliminated by basing the design on self-oscillating mixers. Finally, a retrodirective array is specifically designed for a 10.5-GHz small-satellite network. A network of small satellites promise increased mission flexibility and success by distributing the tasks of a single large satellite. Quadruple subharmonic mixing is used as well as two-dimensional retrodirectivity and circular polarization to accommodate for the power constraints and lack of attitude control of small satellites.