Reduction of Mutual Coupling and Cross-Polarization of Microstrip MIMO Antenna Using Electromagnetic Soft Surface (EMSS)

Mutual coupling, in case of closely spaced microstrip antenna elements, is an inevitable phenomenon degrading antenna performances like gain, radiation pattern, return loss, radiation efficiency, etc. In this paper, an approach toward the suppression of mutual coupling between two closely spaced microstrip radiators is presented for the proposed Multiple-Input-Multiple-Output (MIMO) antennas. The same has been materialized through an insertion of a properly designed Electromagnetic Soft Surface structure between the radiating elements, which acts as an electrical wall between two rectangular patches and reduces the mutual coupling up to 50 dB at resonant frequency of 4.35 GHz. An attempt toward reduction of cross-polarization by 12.5 dB is also achieved with a gain of 5.4 dBi for the proposed antenna. The center-to-center spacing between the antenna elements is kept at 22.1 mm (0.32 lambda). The proposed MIMO antenna structure will be useful in case of radar- and satellite-based communication systems.