One-way ramp to a two-way highway: integrated magnetic-free nonreciprocal antenna interfaces for full-duplex wireless

Since the invention of the radio, transmission and reception have been separated to protect the receiver (Rx) from being jammed by self-interference (SI), i.e., the interference that comes from the colocated radio transmitter (Tx). This separation is called duplexing. Today's wireless systems still rely on duplexing to avoid SI-many short-range or local area radios, such as Bluetooth and WiFi transceivers, transmit and receive in nonoverlapping time slots, called time-division duplexing (TDD), while other modern wireless systems, such as the majority of today's cellular systems, use frequency-division duplexing (FDD) to separate the transmission and reception in the frequency domain. Both TDD and FDD are half duplex, where the separation of the transmitted and received signals of a single user in either frequency or time causes.