Modelling and Analysis of a Compact Quad‐Band Monopole <scp>MIMO</scp> Antenna With Improved Isolation and High Gain for <scp>5G</scp> and Wi‐Fi 6 Systems

ABSTRACT This proposed research demonstrates a quad‐band compact MIMO antenna with excellent gain and enhanced isolation, specifically designed for 5G and Wi‐Fi 6 wireless network applications. The radiating element has three different monopole structures: a flipped G ‐shape, an angled U ‐shape, and an inverted L ‐shape. The proposed MIMO antenna is quite small, only 25 × 48 × 1.6 mm 3 . To improve isolation, a simple rectangular patch element has been inserted between two separated partial ground planes. The suggested MIMO antenna has fractional bandwidths of 18.47%, 5.56%, 20.83%, and 8.07% at 1.86, 2.33, 3.54, and 5.64 GHz, respectively. Isolation remains better than −20 dB across all working bands. The highest isolation is −54.27 dB at 5.64 GHz. The measured results show stable radiation in all directions in the H ‐plane and a nearly bi‐directional pattern in the E ‐plane. The peak gain is 7.74 dBi at 5.64 GHz. The antenna shows good diversity, with an ECC of less than 0.003, a MEG difference of less than 3 dB, a DG of more than 9.995 dB, a TARC of less than −10 dB, and a CCL of less than 0.4 bits/s/Hz. The proposed antenna achieved quad‐band operation with high gain while maintaining effective isolation using a simple compact rectangular patch, thereby avoiding the need for complex decoupling networks, reducing design/manufacturing burden, and ensuring excellent MIMO metrics with a compact geometry. Consistent results from simulations and measurements validate the antenna's viability for use in sub‐6 GHz NR 5G and Wi‐Fi 6 networks.