Circular Polarization MIMO Antenna using Sequentially Rotated Feeding Network for WLAN Applications

Abstract

This work presents a wideband circularly polarized (CP) MIMO antenna operating around 5.5 GHz. The design consists of two identical 2 2 subarrays using aperture-coupled microstrip elements. A 5 mm air gap between substrates is introduced to enhance impedance bandwidth, while a sequential phase feeding network ensures stable CP performance across a wide frequency range. The antenna is analyzed through fullwave simulation software of CST Studio Suite and validated by measurements on a fabricated prototype. Results show a 62.9% impedance bandwidth (4.217.67 GHz) and a 40% 3-dB axial ratio bandwidth (5.17.3 GHz). The antenna achieves a peak gain of 11.5 dBi with inter-element isolation exceeding 25 dB. These results demonstrate its suitability for wideband CP MIMO applications.