A Single-Aperture 0°-120°-240° Triple-Polarized Planar Compact Circular Monopole Array with a Single-Stage Decoupling and Matching Network

This paper proposes a compact circular monopole array (CCMA) that can emit 0°-120°-240° linearly polarized beams at the boresight direction with a single aperture. This CCMA consists of three printed monopole antennas azimuthally separated by 120° and backed by a reflector located at a quarter-wavelength distance apart. At 2.42 GHz, the mutual coupling induced by the non-orthogonal beams is canceled by 25 dB through a shunt connected single-stage decoupling and matching network (DMN). Moreover, this CCMA achieves a stable broadside gain of 5.4 dBi for all three polarizations and a combined 10-dB-return-loss and 15-dB-isolation bandwidth of 200 MHz while retaining 78% efficiency and an envelope correlation coefficient (ECC) less than 0.06.