Metasurface-based Circularly Polarized Dual-Port MIMO Antenna for C-band Uplink Applications

The rectangular-shaped metasurface (MTS)- based circularly polarized (CP) dual-port MIMO antenna was proposed. The proposed rectangular-shaped MTS-based CP dual-port MIMO antenna included two substrate layers (upper and lower). The periodic 4×4 rectangular-shaped MTS elements on the upper layer functioned as CP polarizers. Also, the lower substrate layer comprised the microstrip probe feed and ground plane which generated a linearly polarized (LP) wave. The proposed rectangular-shaped MTS-based CP dual-port MIMO antenna at 5.3 GHz achieved impedance bandwidth (IBW) of 30.9% (4.86 – 6.5 GHz) and axial ratio (ARBW) of 14% (5.16 – 5.9 GHz). The maximum gain was 7.3 dBi at 5.1 GHz. The ECC was lower than 0.002, and DG was greater than 9.98 dB between entire frequency ranges. The direction of the radiation was right-hand circular polarization (RHCP). The dimension of proposed rectangular-shaped MTS-based CP dual-port MIMO antenna was 1.342λ0 × 0.652λ0 × 0.0372λ0.

I. Introduction

Multiple-input multiple-output (MIMO) antennas [1] are challenges in modern wireless communication systems (i.e., 4G LTE, sub-6 GHz new radio and mm-wave). The variety MIMO antennas overcome the large channel-capacity and high data-rate. The MIMO antenna could be investigated the diversity performance [2] by various metrics (i.e., envelope correlation coefficient (ECC), diversity gain (DG), mean effective gain (MEG), channel capacity loss (CCL), and total active reflection coefficient (TARC)). In [3], the flag-shaped dual-port MIMO antenna with mutual coupling reduction using metamaterial for Sub-6 GHz 5G applications achieved broad IBW of 93.7% (2.95 – 6.23 GHz) at 3.5 GHz, ECC was less than 0.025, and DG was greater than 9.95 dB. In [4], the quad-band 4×4 MIMO antenna array for mm-Wave 5G applications achieved four resonance (28, 38, 60, and 73 GHz). Also, the ECC, DG, MEG, and CCL were 0.003, 9.98 dB, 3 dB, and 0.4 bits/s/Hz, respectively. In [5], four-port 5G mm-wave MIMO antenna array for mobile applications achieved wide IBW of 59% (24.1 – 40.6 GHz), ECC < 0.001, and DG > 9.99 dB. However, those MIMO antennas [3]-[5] were linearly polarized wave radiation and low radiation efficiency.