Multi-port monostatic antenna system with improved interport isolation for 2.4GHz full duplex MIMO applications

Abstract

ABSTRACT This paper presents a five (05)-port proximity coupled monostatic patch antenna having four (04) linearly co-polarized ports (same polarization for two-transmit and two-receive ports) for 2.4 GHz in-band full duplex (IBFD) 2-order MIMO (multi-input multi-output) wireless applications. The employed differential receive mode mechanism and single-tap self-interference cancellation (SIC) circuit achieves high isolation between transmit (Tx) and receive (Rx) ports for IBFD operation. The fifth port is dual polarized with respect to the first four (04) ports to provide intrinsic isolation through polarization diversity. The implemented antenna system provides 10 dB return-loss bandwidth of more than 200 MHz for all five ports. The measured MIMO isolation (Tx-Tx ports and Rx-Rx ports) is better than 15 dB and full duplex Tx-Rx isolation ≈ 20 dB between linearly co-polarized ports for 200 MHz bandwidth. Moreover, the interport isolation between Tx ports (Rx ports) and dual polarized port (port 5) > 30 dB (25 dB) in 200 MHz bandwidth in addition to better than 60 dB (27 dB) peak isolation. To the best of our knowledge, it is the first type of such monostatic antenna with multiple co-polarized and dual polarized ports for full duplex MIMO applications.