Ultra-Wideband Antennas and Propagation. Volume 1: Antenna Design, Predictions,and Construction

摘要

In this report we begin the development of two types of Impulse Radiating Antenna(IRA). These two designs include a 23-cm diameter reflector IRA, with an F/D of 0.38, and a solid dielectric-lens IRA, or dielectric-immersed lens IRA. This latter design is a Transverse Electromagnetic (TEM) horn immersed in a dielectric, with a prolate spheroidal lens interface to air. The reflector IRA consists of a paraboloidal reflector, fed by a conical 4-arm feed, whose combined input impedance is 200 omega. The lens IRA was constructed from a solid block of polyethylene, conical in shape and capped by a prolate spheroid. It can be short because of the prolate spheroidal lens. In addition, since the TEM feed is filled with dielectric, it will provide a better match to 50 omega when compared to an air-filled TEM horn with a lens. Since there are fewer dielectric interfaces with this design, there will also be fewer reflections, thereby reducing Fresnel loss.