Non-reciprocal tunable low-loss bandpass filters with ultra-wideband isolation based on magnetostatic surface wave

A new type of non-reciprocal C-band magnetic tunable bandpass filter with ultra-wideband isolation is presented. The BPF was designed with a 45° rotated yttrium iron garnet (YIG) slab loaded on an inverted-L shaped microstrip transducer pair. This filter shows an insertion loss of 1.6∼2.3dB and an ultra-wideband isolation of more than 20dB, which was attributed to the magnetostatic surface wave. The demonstrated prototype with dual functionality of a tunable bandpass filter and an ultra-wideband isolator will have many applications in RF front end and other microwave circuits.