A Four-Port CSRR-Loaded Dual-Band MIMO Antenna With Suppressed Higher Order Modes

In this paper, we propose a compact four-port dual-band MIMO antenna with suppressed higher order modes (HOMs). First, complementary split ring resonator (CSRR) loading is used on a square microstrip antenna to achieve simultaneous miniaturization and dual-band response. Next, the HOMs in the proposed CSRR loaded MIMO configuration are analysed using equivalent circuit model as well as surface current distribution plots. By placing a single shorting post close to antenna center line, these HOMs of the four-port dual-band MIMO antenna are then suppressed, while maintaining satisfactory mutual coupling (<−11 dB) and impedance matching (<−15 dB) performance in the operating band. Furthermore, simulated and measured values of total active reflection coefficient (
TARC
), envelop correlation coefficient (
ECC
) and channel capacity loss (
CCL
) are within the desired levels of −10 dB, 0.5 and 0.5 bits/s/Hz respectively, signifying good diversity performance of the proposed MIMO antenna.