A Coupled-resonator Decoupling Network for full-duplex radios

Full-duplex radios realize simultaneous bi-directional communications in the same frequency band. However, one of the bottlenecks is how to mediate the self-interference (SI) between the transmitter (Tx) and the receiver (Rx). In this paper, a novel passive microwave device called Coupled-resonator Decoupling Network (CRDN) is proposed. A prototype CRDN is built and tested for proof-of-concept, where the four-port device consists of two inter-coupled lines of coupled resonators. The SI is suppressed from -17 dB to below -41 dB within a frequency range of 50 MHz. This performance is superior to other RF front end SI cancellation schemes and demonstrates the potential applications of such device in a full-duplex wireless communication system.