Enhanced 4-Port MIMO Antenna Based on Electromagnetic Mutual Coupling Reduction Using CSRRs Metamaterials for Sub-6 GHz 5G Applications

Abstract

A multi-input multi-output (MIMO) antenna is presented in this paper. The proposed antenna is formed by four (04) radiating patch elements of different sizes and shapes (rectangular and circular). These elements are excited by four feed ports, each port is parallel to three other adjacent ports. All elements are etched on the upper face of the FR4_Epoxy dielectric substrate for electrical dimensions 1.260  1.050  0.0190 (0 is calculated at an operating frequency of 3.75 GHz). In order to improve the performance of our MIMO antenna, nine (09) complementary metamaterial resonators (CSRRs) of compact sizes are printed on the ground plane of the overall structure. These symmetrical rectangular and circular CSRRs act as an isolator between the radiating elements which contributes to the reduction of the mutual coupling between these adjacent elements. The obtained results reveal that the proposed sub-6 GHz antenna operates in the 5G band at 3.61 GHz (3.3-4.2 GHz) with high port isolation (lower than 28 dB). In addition, the antenna loaded with CSRRs demonstrates good MIMO performance with an envelope correlation coefficient (ECC) of less than 0.07, more than 1360 MHz bandwidth, negligible mutual coupling, and a gain of 15.79 dB. The suggested MIMO sub-6 GHz antenna is suitable for 5G applications.