Bidirectional Dual-Port Quad-Mode Wideband In-Band Full-Duplex Transmit-Reflect-Array Antenna With High Aperture Efficiency for High-Throughput Communication Systems

The operation mechanism and physical verification of the bidirectional dual-port quad-mode In-band full-duplex (IBFD) transmit-reflect-array (TRA) antenna are proposed in this article. This is the first IBFD array with bidirectional radiation capability and also the first TRA with IBFD functionality which actualizes the advantages of both the IBFD and TRA by a single radiation array. The proposed bidirectional IBFD TRA can theoretically double the throughput and quadruple the spectral reuse efficiency of the IBFD communication system equipped with it. The IBFD TRA is built by a bidirectional full-duplex array and two feeding horns positioned on both sides of the array. One horn connects the Tx chain and the other connects the Rx chain. The unit of the array is constructed by a bidirectional full-duplex quad-mode topology structure which has two orthogonal modes in both forward and backward directions. The orthogonal modes are used to build Tx and Rx channels in both directions which can greatly reduce the self-interference. Therefore, the simultaneous transmit and receive and Tx/Rx self-interference cancelation in both directions can be completed at the element level, avoiding interleave of the Tx and Rx, and a high aperture efficiency can be eventually achieved by arranging the proposed bidirectional unit into an array. To obtain the bidirectional scattering properties of the proposed unit, a semi-analytical method is proposed based on equivalent-network-assisted Jones matric derivations. Furthermore, a bidirectional phase calculation procedure is proposed for quickly ascertaining the distributions of three phase-modulating variables. Finally, the proposed IBFD TRA is experimentally verified at Ku-band, realizing high figures of metrics, e.g., bidirectional coverage, simultaneous transmit and receive, wide operating bandwidth, and high aperture efficiency.