On the design and analysis of quad element UWB MIMO antenna with various mutual coupling reduction techniques for indoor wireless communications

This research article presents the design of a quad-port UWB MIMO antenna incorporating different mutual coupling reduction techniques for indoor wireless applications. Initially, a single-element UWB antenna is designed on an FR4 substrate with dimensions of 30× × 30 × 1.6 mm³ and is fed by a micro strip line. The proposed antenna element operates over the frequency range of 3.1–10.8 GHz. The designed unit element serves as the fundamental structure for the MIMO antenna system. The overall dimensions of the quad-element MIMO antenna are 68 × 68 mm². Various mutual coupling reduction techniques, such as a decoupling structure, a neutralization line technique, and the proposed radiator tilting method, are implemented independently to reduce coupling between the radiating elements. The performance of the quad-port UWB MIMO antenna is then analyzed in terms of inter-element spacing, Envelope Correlation Coefficient (ECC), and Diversity Gain (DG). The proposed radiator tilting method provides a significant improvement in antenna performance, achieving ECC 〈 0.037 and DG 〉 9.9, with a 3 mm reduction in inter-element spacing.