A Compact Wide-Band Circular Slot Quad-Port MIMO Antenna for 5G Wireless Applications

This paper introduces a 4-port antenna tailored for 5G, operating in the 4.4 to 7.25 GHz (Fractional Bandwidth is 48.9%) range with a 10 dB impedance bandwidth. The operating bandwidth includes the n79 band (4.4-5 GHz), 5G WLAN band (5.125-5.825 GHz), and Wi-Fi 6E band (5.925 to 7.125 GHz). Constructed on a compact FR4 substrate (0.057 lambda x 0.057 lambda x 0.0018 lambda (where lambda is the wavelength at 4.4 GHz), it exhibits robust performance in fabrication and measurements. The single antenna covers a total area as small as 20 x 17.6 mm(2), which enables the compactness of the MIMO antenna with a gain of up to 6 dBi and 85% radiation efficiency; it supports MIMO with a low correlation coefficient (< 0.02), high diversity gain (up to 9.98 dB), and minimal channel capacity loss (0.25 bps/Hz). The Total Active Reflective Coefficient (TARC) is computed to validate MIMO performance over the operating bandwidth. Featuring bidirectional radiation patterns in both E-plane and H-plane, the antenna is well suited for 5G applications, demonstrating potential for future wireless systems.