Non-Magnetic Circulator Using Spatio-Temporal Modulation of Mixed Static and Time-Modulated Resonators

Abstract

This paper presents the design of a non-magnetic microwave circulator using mixed static and time-modulated resonators. By effectively coupling static resonators with time-modulated resonators, the proposed circulator can achieve a low forward transmission insertion loss and a wide reverse isolation bandwidth. Wideband reverse isolation is achieved by creating two isolation nulls within the passband. For the experimental validation, a microstrip line circulator was designed, simulated, and fabricated at a center frequency of 1.75 GHz. The measurement results agreed closely with the simulations and exhibited a reverse isolation higher than 18 dB over a bandwidth of 80 MHz.