Compact circular ring shaped monopole UWB MIMO antenna

This paper presents a simple and a compact MIMO antenna for Ultra Wideband applications. The proposed structure contains two circular ring shaped monopoles which is kept parallel to each other. The physical separation between the radiating elements is about 0.25λ and the mutual coupling obtained is about 20 dB throughout the band. Ground slots (GS) and extended ground plane (EGP) are the means utilized to achieve high isolation. The antenna is optimized to provide more than 113.5 % impedance bandwidth below VSWR 2 (S11 < −9.5 dB) for the 2.87 GHz to 10.4 GHz band. The designed structure has length and width of 30 × 26.4 mm2 when etched on one of the sides of the cost effective FR4 substrate thickness which is of 1.6 mm. Apart from the MIMO performance metrics, which include, ECC, Diversity Gain and Mean Effective Gain, the time domain analysis, radiation and gain patterns are measured and presented too. This analysis guarantees that this antenna is suitable for ultra band MIMO applications.