Stripline-Fed Archimedean Spiral Antenna

An inward-fed two-arm Archimedean spiral antenna is proposed, which integrates a stripline feed network into one of the spiral arms. A broadband stripline tapered impedance transformer conformal to the spiral's winding provides a novel matching network between the input impedance of the spiral and the characteristic impedance of the stripline. The Dyson-style balun at the spiral's center converts the guided stripline mode to the radiating spiral mode. The transformation from a gap-fed design to a stripline-fed design is provided to illustrate the design process. Measured and simulated results for a probe-fed design operating from 2 to over 20 GHz are provided to illustrate the synthesis and performance of a demonstration antenna.