A high-gain, low-profile, dual-band 28/38 GHz (n261& n260), circularly-polarized MIMO antenna based on artificial magnetic conductor metasurface reflector (AMCMT) for 5G millimeter-wave communications

Abstract This paper introduces a space-efficient dual-band MIMO antenna operating at 28/38 GHz, featuring optimized radiation characteristics for next-generation 5G communications. The antenna incorporates an artificial magnetic conductor metasurface (AMCMT) reflector to improve isolation and gain without compromising bandwidth. The MIMO antenna consists of four rectangular patches with half-circle slots, while the AMCMTs use square split-ring resonators. Both have dimensions of 26 × 26 mm 2 , with the AMCMTs placed 2.68 mm behind the antenna. Three AMCMT configurations were evaluated; 4 SRRs, 5 SRRs, and a 3 × 3 array of 9 SRRs. The basic MIMO antenna without AMCMTs achieved three bandwidths: 25.46–26.64 GHz, 27.71–31.32 GHz and 34.51–39.73 GHz, with reflections of −26.59 dB and −45.07 dB in the latter two bands. With the 4-SRR AMCMTs, the antenna covered 27.34–30.51 GHz and 34.44–38.91 GHz. The 5-SRR design yielded bands of 27.04–30.62 GHz and 34.12–38.65 GHz. The full 3 × 3 array design achieved superior results, maintaining dual-band operation at 27.32–30.92 GHz and 34.91–40 GHz. Isolation improved from <−17.5 dB to <−26 dB at 28 GHz and from −12.11 dB to −27.32 dB at 38 GHz. Peak gain increased by 53%, from 5.56 dBi to 8.52 dBi. At 28 GHz, the gain improved from 5.56 dBi to 8.23 dBi, while at 38 GHz, it rose from 3.91 dBi to 8.52 dBi. Furthermore, diversity analysis revealed superior performance parameters; ECC of <0.05, DG > 9.95, CCL < 0.4 b/s/Hz, and TARC <−10 dB. A rigorous electromagnetic analysis of electric field and surface current distributions was conducted to elucidate the fundamental mechanisms by which the AMCMT enhances the MIMO antenna’s performance metrics. This compact design outperforms recent comparable antennas in size, isolation, and gain, validating its capabilities for emerging 5G millimeter-wave implementations where spatial diversity and high bandwidth are critical. The results demonstrate the effectiveness of the AMCMTs approach in optimizing MIMO antenna performance for emerging 5G systems, with the full 3 × 3 array configuration providing the best overall performance across all measured parameters.