Reduction of cross-polarization radiation of E-shaped microstrip antenna array using spiral-ring resonator

In this article, the design and analysis of a (2×2) microstrip patch antenna array integrated with spiral ring resonator (SRR) is introduced. It is designed to function in the 5.25 GHz which corresponds to IEEE 802.11a (VSWR<;2, data rate 54Mbps/ B.W of 20 MHz and S-parameters, S₁₁ <;-20dB where i≠j) wireless LAN application. The proposed antenna array is a high gain, low-cost, low weight base station antenna. The characteristic analysis such as return loss (RL), bandwidth (BW), and radiation patterns of the antenna array with and without SRR have been investigated. In this paper, bandwidth of 225MHz (For RL<;-10dB) and antenna gain of 12.975 dBi have been achieved. The cross-polarization radiation has been studied numerically by introducing SRR. The size of the SRR has been optimized for minimum cross-polarization radiation. The difference between co-polarization and cross-polarization(X-pol) has been observed 21.4887dBi with optimized SRR and 17dBi without SRR. The X-pol radiation is reduced by around 4.4887 dBi and this has been achieved numerically. Prototype antenna has been fabricated, tested and the results are in good agreement with the simulated results. A study has been carried out with and without SRR and it has clearly observed that antenna characteristics such as RL and, radiation pattern have improved.