Characterization, Design and Optimization of Low-Profile Cavities for UWB Spiral Antennas

In this paper, we present a methodology for developing very low profile, hybrid, cavity-backed UWB spiral antennas from a precision electromagnetic material characterization standpoint. Using our method, we have accurately characterized, designed and optimized the dimensions of a 2-18GHz, cavity-backed Archimedean spiral antenna. The simulation and measurement results show that the antenna demonstrates excellent axial ratio and gain-bandwidth performance while maintaining an absorptive cavity depth of only 0.625 inches. The procedure can be extended to the design and optimization of any low-profile spiral radiator required to operate over extremely broad frequencies.