Noninterleaved Wideband High-Gain Tx/Rx Array Antenna With High Aperture Efficiency for In-Band Full-Duplex Systems

A Tx/Rx noninterleaved array antenna for in-band full-duplex (IBFD) systems is proposed in this article. Distinct from the reported Tx/Rx interleaved arrays, the proposed array adopts a novel dual-mode radiation unit that can simultaneously operate in Tx and Rx manners, without requiring the decoupling elements between the Tx units and the Rx units while arranging more radiation units to realize a higher aperture efficiency. The noninterleaved array consists of several full-duplex dual-mode units and a feed network. The dual-mode unit can simultaneously operate in the radiation mode and reflection mode at the same frequency. In radiation mode, a high-gain array (Rx) can be constructed by combining the feeding network. In reflection mode, a high-gain reflectarray (Tx) can be implemented by combining a spatial feed. The polarization statuses of the radiation mode and reflection mode are right-hand circular polarization (RHCP) and LHCP, respectively, which greatly decreases the self-interference (SI) between the Tx and Rx channels. The proposed IBFD array is designed, fabricated, and measured at X-band with an operating bandwidth of 23.1% and 35.2% in the Tx and Rx channels, respectively. The maximum gain in two channels is 23.1 dBic and 23.6 dBic with a high aperture efficiency of 50.8% and 58.1%. The passband isolation is higher than 35.0 dB.