A compact five-port millimetre-wave MIMO antenna with polarization and pattern diversity for 5G wireless communication

Abstract

The present proposed work demonstrates a compact five-element millimetre-wave (mm-wave) multiple-input–multiple-output (MIMO) antenna with polarization and pattern diversity for 5G wireless communication applications. The geometry consists of three chamfered-edge rectangular patch geometries, each connected with Ports 2, 4 and 5, among which Ports 4 and 5 exhibit the right-hand circular polarization (RHCP) behaviour at 28 GHz in the broadside direction, and Port 2 displays the left-hand circular polarization (LHCP) response. At the same time, two printed dipoles (connected at Ports 1 and 3) are placed at opposite ends and provide end-fire linear polarization (LP) radiation at the same resonant frequency. The antenna is designed, simulated, fabricated, as well as experimentally verified with the simulated responses. The measured 10-dB fractional impedance bandwidths (FIBWs) of 21.05%, 3.07%, 25.0%, 5.85% and 4.81% are achieved at Ports 1, 2, 3, 4 and 5 respectively. The isolation between the ports varies from 22 to 61 dB, thereby showing a minimal inter-element coupling without using any additional decoupling structure. The peak realized gains of 6.8–7.01 dBi at Ports 1 and 3, and 6.2–9.05 dBic at Ports 2, 4 and 5 are obtained. The radiation efficiency is also varied in the 89–97% range. The proposed MIMO antenna is suitable for 5G wireless applications owing to its several novel features, such as small footprint (1.4λ × 4.26λ, where λ is the operating wavelength at 28 GHz), good isolation, acceptable bandwidth and polarization (RHCP/LHCP/LP) as well as pattern (broadside/end-fire) diversity characteristics. © 2025 Elsevier B.V., All rights reserved.