Polarisation control of a loop antenna by PIN diodes

A wire loop antenna with two electronic switches is introduced to control polarisation (left-hand, right-hand or linear polarisation). The loop is fed through an electromagnetically coupled monopole antenna. The loop and the monopole are located on a ground plane. The switching circuit with PIN diodes is installed near the feed point of the monopole to obtain symmetric radiation patterns. Good axial ratio and impedance characteristics are obtained. The experimental results show the capability of the polarisation control by electronic switches