Microstrip Antenna Design Backed Modified Ground for Circularly Polarized Response

Microstrip or patch antenna, have gained lot of importance over last two decades due to their various advantages like low volume, low profile configuration, which makes their easy integration with other system devices. Also microstrip antenna using defected ground plane structure gained importance as they yield compact, dual band, wideband and circular polarized response, with modified ground. The paper proposes a square microstrip antenna design backed by defected ground plane, for realizing circular polarized response. Circular polarization is obtained due to degeneration of orthogonal modes, created due to the defects in the ground. The proposed antenna on thinner Arlong substrate (
$0.016\lambda_{\mathrm{g}}$
) yields respective axial ratio and input impedance bandwidth of 16 (0.93%) and 37 MHz (2.14%). The proposed low profile antenna realizes gain larger than 5 dBi for the frequency range of axial ratio less than 3 dB. An equivalent of the proposed configuration will find application in personal communications devices around 900 and 1800 MHz frequency spectrum.