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

Abstract

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.

Keywords

• Full-duplex
• MIMO
• mutual coupling reduction
• microstrip antenna
• self-interference cancellation