Method of electronic beam steering for circular switched parasitic dipole arrays

Abstract

This paper presents a method of electronic beam steering for a smart antenna system based on a switched parasitic array. The antenna system is made up of circular array of half wave dipoles, with four parasitic elements positioned equidistantly, surrounding one active central element. All parasitic elements are assumed to be switched between short-circuit and opencircuit states to change their resonant length. The switching between parasitic elements’ states is attained by connecting a switch that assumes ON/OFF states at the centre of each parasitic element. This allows some parasitic elements to act as reflectors while shortcircuited, whereas other parasitic elements act as directors when open-circuited. Thus, the direction of maximum gain is controlled by open- and shortcircuiting the parasitic elements. By appropriately selecting correct combination of short- and opencircuited parasitic elements together with the active element, a set of radiation patterns is formed covering the horizontal plane. Results for the horizontal coverage are presented with the main beam(s) directed at 00, 900, 1800, and/or 2700, as well as for an omnidirectional configuration resemblance. It is expected that increasing the number of parasitic elements will improve directional properties further.