Mutual Coupling Effect and Reduction Method with Modified Electromagnetic Band Gap in UWB MIMO Antenna

Abstract

In this paper, an effective technique for mutual coupling (MC) reduction between antenna elements of two multiple input multiple output (MIMO) microstrip patch antennas operating in the ultra-wide band (UWB) between 3.1 and 13.5 GHz is presented. The antenna array separation was kept at 44 mm for investigation, and the isolation was achieved through a modified electromagnetic band gap (MEBG) decoupling structure. The MEBG is embedded behind the radiating elements connected to the ground plane. HFSSv15 software was used to design and simulate the antenna. The effectiveness of the antenna and the MC reduction method was examined with and without the MEBG structure. The results revealed that the MC between the MIMO antenna elements was minimized when the MEBG structure was introduced. An MC of about −23 dB was obtained over the entire UWB frequency spectrum. This is more than a 10 dB improvement over the reference antenna (without the MEBG structure). Without limiting the effectiveness of the antenna when the MEBG structure was introduced, the results of the envelope correlation coefficient (ECC) gave the antenna a satisfactory diversity performance. The MEBG UWB MIMO antenna has an ECC less than 0.09 with a wide bandwidth. In addition, the total gain and the Voltage Standing Ware Ratio (VSWR) results were analyzed, which show that the performance of the antenna was not degraded while reducing the MC effect between the MIMO antenna elements.