Electronically-steered antennas with 360° coverage for mobile use

This paper describes several electronically-steered phased-array antennas for use in the HF, VHF and UHF bands. An approach is described which uses 4 vertical elements above the ground plane in a square pattern. With proper phasing, a directive beam of 97° width may be electronically switched in quadrants to provide full 360° azimuth coverage. This antenna provides significant forward gain and a high front-to-back ratio to provide suppression of interference not in the path of communication. An alternate approach uses three elements in a triangular configuration, each beam covering 120° of azimuth. Methods will be described for mode selection of omni and the four quadrantal directions using semiconductor switching.