Circularly polarized reconfigurable microstrip loop antenna using parasitic patches and PIN diodes

This research proposes a novel circularly polarized (CP) reconfigurable microstrip loop antenna for 2.4-2.5 GHz advanced wireless communication using two parasitic patches and two PIN diodes. The reconfigurable antenna can alternate between right hand circular polarization (RHCP) and left hand circular polarization (LHCP) at the main beam by manipulating the ON/OFF status of the PIN diodes. Simulations were carried out for the optimal antenna parameters, and an antenna prototype was fabricated and experiments were undertaken. The simulation and measured results are in good agreement. The antenna achieves an impedance bandwidth of 2.4-2.5 GHz and unidirectional radiation pattern with a maximum gain of 5 dBic and 3-dB axial ratio for both RHCP and LHCP. As a result, the proposed reconfigurable antenna could be utilized to improve wireless communication performance. In essence, the novelty of this research lies in the utilization of parasitic patches and shorted PIN diodes to transform linear to circular polarization; and the reconfigurability of polarization between RHCP and LHCP.