A Non-Reciprocal Microstrip Bandpass Filter Based on Spatio-Temporal Modulation
A magnetless non-reciprocal filter based on spatio-temporal modulation is demonstrated in this paper. By modulating the resonant frequencies of the resonators with a progressive phase shift, a large difference between the forward and backward transmissions can be achieved, realizing a filter with non-reciprocal amplitude responses. As a proof-of-concept, a 2-pole microstrip filter centered at 1.0 GHz is designed and characterized. The non-reciprocal transmission is 11 dB in simulation and 6 dB in measurement, which experimentally validates the proposed concept.