Circularly-Polarized Reconfigurable Microstrip Antenna

Abstract

This paper presents a new design for a circularly-polarized (CP) microstrip patch antenna with switchable polarization sense. The antenna has a circular radiating patch and it is excited by a microstrip feed line through the coupling of a full-wavelength annular-ring slot in the ground plane. First, it is found that the antenna polarization can be switched between vertical and horizontal polarizations when two PIN diodes are used to reconfigure the coupling slot and the open stub of the feed line, respectively. Such a linearly-polarized reconfigurable microstrip antenna can be converted to a switchable CP antenna by embedding a cross slot with unequal lengths into the radiating patch. Details of the designs are described, and both simulated and measured results are presented.