Azimuth-Pattern Reconfigurable Planar Antenna Design Using Characteristic Mode Analysis

In this paper, a patch antenna is proposed with reconfigurable patterns in the azimuth plane. The basic structure of the antenna is a circular patch upon which a vertical slot is etched. In addition, a row of shorting posts along the horizontal direction is placed underneath the patch. With the aid of characteristic mode analysis (CMA), reconfigurable patterns are achieved by synthesizing the currents of different modes. By switching over different sets of feeding ports, four steerable beams capable of covering the entire azimuth plane are obtained. One unique feature is that when the beam is switched to the direction orthogonal to it, the shape of the pattern will be switched accordingly. The antenna was fabricated and measured. The measured F/B ratio is close to 10 dB at 2.08 GHz, and the 3-dB beamwidth in the elevation (azimuth) plane is switchable from 82 degrees (181 degrees) to 190 degrees (91 degrees).