A highly isolated co-linearly polarized in-band full Duplex/MIMO antenna using DGS

In this communication, a highly isolated two-port microstrip patch antenna system using a defected ground structure (DGS) at 5.85 GHz is proposed. Utilizing two orthogonal dumbbell-shaped structures, the DGS significantly reduces mutual coupling between ports to an impressive level of −94 dB (−104 dB simulated). This decrease in coupling facilitates self-interference cancellation in full-duplex (FD) systems without the need of additional components, while still keeping the acceptable performance of the antenna system. In this two-port MIMO/FD system, the individual antenna has a fractional bandwidth of 4.1% with a peak realized gain and efficiency of 6.2 dBi and 95% respectively. In addition, the MIMO performance parameters like envelope correlation coefficient (ECC), total active reflection coefficient (TARC), and channel capacity loss (CCL) are also analyzed and calculated using simulation and measurement. The proposed antenna is validated through the measurement of a fabricated prototype which suggests its applicability for both FD/MIMO systems for the 5G NR-U and upper WLAN bands.