Microstrip Patch Antenna System With Enhanced Passive Self-Interference Cancellation For Full-Duplex/MIMO Applications

This paper presents a compact two-port microstrip patch antenna system designed to enable passive self-interference suppression through enhanced inter-port isolation. The proposed antenna operates at 3.5 GHz, suitable for both MIMO as well as full-duplex transceiver applications. The isolation is significantly improved, achieving ≈ 36 dB without relying on circulators, hybrids, or complex feed networks. This is accomplished using a unique design strategy that combines: (1) electromagnetic field confinement around individual antenna elements using metallic vias, and (2) a near-field decoupling structure (NFDS) positioned within the limited spacing between ports. The antenna also maintains favorable impedance matching and achieves a broadside gain of 4.86 dBi. The design methodology and performance validation are carried out using full-wave simulations in CST Microwave Studio (CST-MWS).