Microstrip Patch Antenna System With Enhanced Inter-Port Isolation for Full-Duplex/MIMO Applications

In this paper, we propose a closely spaced two-port microstrip patch antenna system with significant isolation enhancement (> 90 dB), which can be deployed for MIMO as well as full-duplex transceiver systems. We deploy a resonant combination of rectangular defected ground structure (DGS) and a near-field decoupling structure (NFDS) in the vicinity of a closely spaced (inter-element spacing
$= {0.01\lambda _{0}}$
) two-port microstrip patch antenna system at 5.85 GHz. This drastically reduces the port-to-port mutual coupling (< −90 dB), which can help in self-interference cancellation for full-duplex point of view without any additional circuitry, while still preserving desired impedance matching performance (< −15 dB). The broadside gain of individual antennas in the two port MIMO system is 7.11 dBi, with 97% efficiency and co-to-cross-polar level < 25 dB. The proposed concept is validated by full-wave simulation in CST Microwave Studio, as well as experimental results on fabricated prototype. Moreover, MIMO performance metrics such as total active reflection coefficient (
TARC
), envelop correlation coefficient (
ECC
) and channel capacity loss (
CCL
) are analysed using simulation and measurement.