Triple-band mmWave 4-port MIMO antenna with enhanced isolation for IoT and vehicular communication systems

Abstract

This paper presents a compact 4 × 4 multiple input multiple output antenna designed to operate at triple-band frequencies of 28, 29.58 and 32.82 GHz. The antenna is fabricated on a Rogers RT 5880 substrate with overall dimensions of 13 × 13 × 0.254 mm3. The antenna operates over three frequency bands: 27.70–28.32 GHz, 29.44–29.91 GHz, and 32.72–33.10 GHz, with realized gains of 7.8 dBi, 4.8 dBi, and 7.6 dBi, respectively. Mutual coupling between the antenna elements is effectively reduced by the combined effect of orthogonal element orientation and a fan-shaped slot in the ground plane, yielding isolation levels >22 dB across the three operating bands. The surface current distribution analysis of the perturbed ground plane is presented to demonstrate the decoupling mechanism between the adjacent radiating elements. The antenna exhibits excellent diversity performance, with an envelope correlation coefficient below 0.004, a diversity gain close to 10 dB, a mean effective gain below −3.5 dB, and a channel capacity loss below 0.26 bits/s/Hz. The calculated antenna results are validated with the measurements and found suitable for 5G smartphones, IoT systems and vehicular communications.