Low Cost Lightweight Mode Forming System for Angle of Arrival Estimation

by Stewart, Mark Anthony

Current mode forming systems have high angular resolution and operate over large bandwidths. System size, complexity, and cost restrict the use of these systems to ground-based or large-airframe platforms. A spiral antenna in conjunction with mission- specific modularized planar microstrip mode formers would allow for angle of arrival estimations on smaller platforms such as a medium-sized UAV. This thesis investigates the mode forming characteristics of a planar four arm spiral antenna driven with a planar microstrip mode former designed to operate over a single personal communications band. The theoretical foundation for a closed-form angle of arrival estimation given by Penno and Pasala[3] in “Angle Estimation with a Multi-Arm Spiral Antenna” is analyzed and is compared with models simulated in Numerical Electromagnetics Code. The results of both the theoretical and simulated models are compared to measured data from each realized subsystem and the system as a whole. A determination is made that the simple model presented by Penno and Pasala[3] is not sufficient to determine angle of arrival information, and a more sophisticated model is needed.