Bandwidth and Gain Improvement of a Circularly Polarized Metamaterial-Based Antenna Employing Square Ring-Shaped Defected Ground Structure

Abstract

In this work, a wideband compact and low-profile metamaterial-based antenna has been developed. The antenna bandwidth is improved by employing square ring-shaped defect in the ground plane. The circularly polarized (CP) antenna has been realized by two pairs of radiators and CP characteristics has been obtained by placing two radiators for X-polarized wave and two radiators for Y-polarized wave. Each radiator is designed with epsilon negative transmission line (ENG-TL) to generate zeroth order resonance (ZOR). Simulated results show that the antenna achieves a gain of 4.98 dBiC, which is improved by 0.62 dBiC compared to the structure without square ring-shaped defected ground structure. Also, the operating bandwidth of our proposed antenna improves to 698.6 MHz.