Design and performance of an ultra wideband ceramic-loaded slot spiral

There is a significant interest in the commercial and military sector for antennas which are smaller and broadband. The paper is the first, to the authors' knowledge, that pursues miniaturization of broadband antennas using high-contrast materials (/spl epsiv//sub r/>20). Specifically, we present analysis and measurements of a slot spiral antenna loaded with ceramic materials and demonstrate that a 6 inch aperture can operate down to 70 MHz and up to 4 GHz or more. A previously developed spiral antenna (Filipovic, D.S. and Volakis, J.L., IEE Proc. Microwaves, Antennas and Propag., vol.149, no.2, p.98-105, 2002) is used as a starting point and, prior to ceramic loading, the spiral is first modified and improved to allow for effective utilization of a ceramic superstrate. First, improvements on the existing slot-spiral are outlined and then data for the dielectrically loaded spiral are presented.