A Compact MIMO Antenna with an Equivalent Circuit Model for Satellite Communications, Weather Radar and 5G Mobile Technology

This work presents a four-element multiple-input multiple-output (MIMO) antenna for super high frequency band (SHFB) applications using polarization diversity and cross-neutralization line (CNL). This structure consists of an M-shaped patches with a partial ground plan, powered by a coplanar waveguide (CPW) line. The compact system is based on polarization diversity. This configuration shifts the phase of the four antennas by 90° to provide better isolation between the different antenna ports. The cross-neutralization line blocks the current flowing between the antenna elements and thus reduces mutual coupling. The suggested structure was developed with dimensions of 31×31×1.6 mm³. It can achieve a reflection coefficient of less than -10 dB (S11 < -10 dB) with a total bandwidth of 5.71 GHz (2.82 to 8.53 GHz) and an isolation of more than -10.8 dB over the desired band. Envelope correlation coefficient (ECC) less than 0.25 and diversity gain (DG) bigger than 9.8 dB are obtained and the antenna's radiation and diversity performance are evaluated. An equivalent circuit model is proposed to represent the behavior of the single element antenna. A prototype was fabricated and experimentally tested to confirm the proposed design. In general, simulated, measured, and theoretical results are remarkably matching.