Development of quad MIMO antenna with evaluation of TARC performance

Abstract

A 4× 4 multiple input multiple output (MIMO) antenna is designed to achieve enhanced gain and isolation for the proposed 6 G frequency band (7–24 GHz), covering C, X, Ku, K, and Ka bands. The initial design features a printed ring-shaped monopole antenna integrated with a four-spoke arm, rotated at 45°. A defected ground structure with a staircase pattern beneath the feed line ensures effective impedance matching. This antenna demonstrates improved reflection coefficient, efficiency, and gain across various operational bands, including the X band, Ku band, K band and Ka band. It offers a wide bandwidth of 39.2 GHz (5.8 GHz to 45 GHz) at ⩽ −10 dB. To optimize its performance in multipath environments, a quad-element MIMO configuration has been adopted, leading to bandwidth expansion of 42.4 GHz (2.6–45 GHz) at ⩽ −10 dB and the inclusion of the C band. Additionally, an equivalent circuit model has been developed to analyse the radiator’s impedance and mutual decoupling characteristics. The proposed antenna has been experimentally tested, and the measured values of ECC, diversity gain, gain, and mutual decoupling are found to be 0.005, 9.88, 5.8 dBi, and −22 to −25 dB, respectively. A detailed evaluation of total active reflection coefficient, considering the radiator’s phase angle and the excitation port, is also presented in this study.