Nonreciprocal Bandpass Filter Using Mixed Static and Time-Modulated Resonators

This letter presents a magnet-less nonreciprocal bandpass filter (BPF) that uses coupled static and time-modulated resonators. This coupling allows the nonreciprocal BPF to achieve minimum forward insertion loss (IL) and two pole isolation within the passband and shows wideband and high isolation. The modulation signal is directly applied to the varactor through the transmission line. This design, while simple, nevertheless achieves an excellent nonreciprocal response. We designed, simulated, and experimentally validated a microstrip line nonreciprocal BPF at 1.46 GHz. The results achieved in experiment were consistent with those obtained through simulations; forward IL of 3.10 dB and reverse isolation of 20 dB over a bandwidth of 50 MHz.