A Wideband Circularly Polarized Endfire Microstrip Antenna

In this paper, a novel wideband planar microstrip antenna with a circularly polarized end-fire beam is presented. The antenna comprises a semi-circular disc magnetic dipole and a directive open loop antenna, etched on a two-layer substrate. By choosing appropriate element shapes and separation distances the required characteristics for the generation of circular polarization are achieved. The proposed microstrip antenna is numerically simulated, and a prototype is developed for experimental validation. The antenna resonates at 2.4 GHz and exhibits measured impedance and axial ratio bandwidth of 12.5% and 13.7% respectively. The azimuth and elevation axial ratio beam widths are 89° and 118° correspondingly. The proposed antenna would be a very promising alternative for RFID applications.