Compact dual-polarised microstrip patch antenna with high interport isolation for 2.5 GHz in-band full-duplex wireless applications

In-band full duplex (IBFD) wireless operation can be accomplished by mitigating the self-interference (SI) at the receiver that is caused by coupling of radio-frequency power from its own transmitter. Maximum amount of SI cancellation (SIC) should be achieved at antenna stage to enable full-duplex wireless communication operation at same frequency. This study presents the design and implementation of a compact two-port dual-polarised microstrip patch antenna which uses three-port microstrip patch antenna with 3 dB ring hybrid coupler as SIC circuit to achieve high interport isolation. The implemented antenna provides 57 dB interport isolation between transmit and receive ports at centre frequency of 2.5 GHz with linear orthogonal polarisation and interport isolation is better than 40 dB for 50 MHz bandwidth. The fabricated compact microstrip patch antenna has 3.1 and 3.7 dBi gains for Tx and Rx modes, respectively. The proposed antenna has comparatively wider 10 dB input bandwidth (50 MHz) along with high interport isolation.