Compact Multiband MIMO Antenna for Sub-6 GHz 5G Applications

High-speed and low-loss compact antennas are in great demand due to their requirement in high-performance wireless communication systems. This paper presents a compact circularly polarized rectangular microstrip patch antenna for triple-band applications in the frequency band of the sub-8 GHz (3.1-7.6 GHz) range. The electrical length of the antenna is 0.64 lambda x 0.54 lambda x 0.02 lambda, where lambda is the free space wavelength at the first lower frequency (@3.1 GHz). The simulated and measured results are compared in this scope, and both the results agree with the fractional bandwidth (below -10 dB) of 30.5% (3.1-4.2 GHz @ 3.6 GHz), 19.6% (4.9-5.9 GHz @ 5.1 GHz), and 17% (6.4-7.6 GHz @ 7.2 GHz) at the sub-6 GHz 5G, WLAN, and Wi-Fi 6E band. Maximum isolation of 35 dB is observed at the 5G and WLAN bands and 22 dB at the 6E band with a peak gain of 6.15 dBi. The horizontal and vertical spacing between the edges of the horizontal and vertical patches are 0.12 lambda and 0.14 lambda, respectively. Furthermore, an envelope correlation coefficient (ECC) < 0.006, diversity gain (DG) > 9.99 dB, group delay < 0.4 ns, and maximum radiation efficiency of 98% provide an excellent trade-off among the antenna parameters in the working band along with the 13%ARBW (< 3 dB) in the 5G (3.1-3.6 GHz @ 3.2 GHz) and Wi-Fi 6E band. The quasi-omnidirectional radiation pattern makes it a suitable candidate for operation in 5G broadband and next-generation Wi-Fi 6E services.