A Miniaturized UWB MIMO Antenna Design for 5G Multi-Band Applications

In this paper, an ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna covering the n77, n78, n79, and 6 GHz bands is proposed for 5G applications, which achieves the full coverage of the 5G NR (New Radio) band with a compact geometry. The antenna is fabricated from low-cost printed circuit boards, with the dimensions of 36 mm × 53 mm × 1.6 mm. The MIMO antenna has been designed with two positive octagonal antenna monopole elements, which feature triangular fractal slots and a defected ground plane. Each of these elements is excited by a microstrip feed, and the antenna operates within a bandwidth of 2.92–16.97 GHz, which encompasses the entire UWB frequency range. The utilization of a floor with T-shaped slots and T-shaped stubs serves to minimize the generation of coupling currents between the antenna elements, thereby achieving an isolation of in excess of 19 dB across the entire operating band and a figure in excess of 20 dB in multiple 5G bands. In addition, simulations and measurements show that the antenna has an envelope correlation coefficient (ECC) less than 0.005, a diversity gain (DG) more than 9.98, a total active reflection coefficient (TARC) less than −30 dB, and a channel capacity loss (CCL) less than 0.3 bit/s/Hz in the operating frequency band, with good gain and stable radiation characteristics. The designed antenna has the potential for significant applications in 5G wireless communications. © 2025, Electromagnetics Academy. All rights reserved.