Optimization of a Planar “Bull-Eye” Leaky-Wave Antenna Fed by a Printed Surface-Wave Source

A microstrip-based leaky-wave antenna for two-sided frequency beam scanning and broadside radiation is presented. In particular, the optimized “bull-eye” ring structure is designed to support leakage of the fundamental TM mode of the guiding structure in a regime without any other leaky- or surface-wave modes. Also by following suggested design rules, to achieve good isolation between the printed rings and the TM source, a beam scan angle range of 121° can be realized over an operating bandwidth of more than 40% with antenna mismatch losses of less than 0.14 dB. Supporting numerical calculations are also in agreement with the simulations and antenna measurements.