Circular Microstrip Antenna with Circular Shorting Posts for Improved Polarization Purity

A probe-fed circular microstrip antenna (CMA) with shorting posts has been studied to minimize the cross-polarization (XP) on the broadside direction on the principle H-plane. A number of circular shorting posts, shorting the patch and ground plane on the periphery of the patch have been proposed. Improvement in co-polarized (CP) to cross-polarized (XP) radiation is obtained on increasing the number of the shorting posts. This proposed structure is investigated using two substrates of RT-Duroid and FR4-Epoxy having dielectric constant er = 2.33 and er = 4.4, respectively.