4-Port Octagonal Shaped MIMO Antenna with Low Mutual Coupling for UWB Applications

A 4-port multiple-input multiple-output (MIMO) antenna exhibiting low mutual coupling and UWB performance is developed. The octagonal-shaped four-antenna elements are connected with a 50 Ω microstrip feed line that is arranged rotationally to achieve the orthogonal polarization for improving the MIMO system performance. The antenna has a wideband impedance bandwidth of 7.5 GHz with S₁₁ < −10 dB from (103.44%) 3.5–11 GHz and inter-element isolation higher than 20 dB. Antenna validation is carried out by verifying the simulated and measured results after fabricating the antenna. The results in the form of omnidirectional radiation patterns, peak gain (≥4 dBi), and Envelope Correlation Coefficient (ECC) (≤0.01) are extracted to validate the suggested antenna performance. As well, time-domain analysis was investigated to demonstrate the operation of the suggested antenna in wideband applications. Finally, the simulated and experimental outcomes have almost similar tendencies making the antenna suitable for its use in UWB MIMO applications.