A non-reciprocal bandpass diplexer

© 2021 Wiley Periodicals LLCThis letter presents a non-reciprocal diplexer with integrated functions of a conventional bandpass diplexer and two isolators. This is achieved by spatio-temporally modulating the resonator frequencies in a coupled-resonator diplexer. Due to the high channel-to-channel isolation, the diplexer channels can be independently modulated without affecting each other. A microstrip diplexer example is demonstrated with good agreement between the measurement and the simulation. The fabricated diplexer has two non-reciprocal bandpass channels at 829 and 997 MHz, with a minimal insertion loss of 4.9 and 6.1 dB, and a 20-dB isolation bandwidth of 38 and 37 MHz, respectively. To the best of the authors' knowledge, this is the first time that a non-reciprocal diplexer has been presented.