An EBG-Driven 2-Port MIMO Antenna Featuring Enhanced Isolation and Circular Polarization for IEEE 802.11ad JC&S Terminals

This paper addresses the issue of high cost and fabrication complexity associated with isolating circularly polarized (CP) waves in a compact multiple-input-multiple-output (MIMO) antenna for joint communications and sensing (JC&S) in IEEE 802.11ad spectrum. A printed circuit board (PCB)based dual-port antenna engaging $3.83 \lambda \times 3.83 \lambda \times 0.04 \lambda$ area at the center frequency of $57.55 \mathrm{~ G H z}$ is proposed. The antenna comprises of a microstrip patch attached to a grounded coplanar waveguide (CPW), with a signal track designed to enable CP radiations. A metallic grid-based electromagnetic bandgap (EBG) structure was engineered and positioned between the two antenna elements to attain a peak isolation of 50.83 dB. The distance between each pair of microstrip parts was subjected to the fabrication capabilities of conventional PCB manufacturers. The final arrangement yielded a gain of $\approx \mathrm{1 0} \mathrm{d B i}$ and efficiency of $\gt \mathrm{8 5 \%}$. The simulation results have been validated through cost-effective fabrication and measurements. Compared to the latest designs, the proposed antenna is fairly competitive.