Análise no domínio do tempo de antenas duplo-refletoras para cobertura omnidirecional

Abstract

This work aims to develop a formulation to obtain the time-domain electric far field radiated by classical omnidirectional dual-reflector antennas fed by a TEM coaxial horn. These antennas are capable of operating in microwave and millimeter wave bands and they have been extensively investigated in frequency-domain. However, the time-domain analysis of dual-reflector antennas is still a rather unexplored topic. The time-domain electric field impulse and step responses are determined by means of analytical inversion of the corresponding frequency-domain solution obtained using Geometrical Optics (GO) principles and the Aperture Method. The developed formulations are valid for the four configurations of classical dual-reflector antennas for omnidirectional coverage with arbitrary main-beam direction in the elevation plane: omnidirectional axis-displaced Ellipse (OADE), Hyperbola (OADH), Cassegrain (OADC) and Gregorian (OADG). An algorithm was developed to synthesize the four classical configurations and obtain the radiation pattern of these antennas, as well as provide approximate numerical results for the step response in the time domain. In this work, only results for OADE and OADC configurations are presented because they are more compact.