Micro-machined Tunable Magnetostatic Forward Volume Wave Bandstop Filter

We have successfully designed, fabricated and characterized a planar monolithic yttrium iron garnet (YIG) Chebyshev bandstop filter on gadolinium gallium garnet (GGG) substrate with tunable frequency, low insertion loss, and high rejection. This filter is created in YIG micro-machining technology that allows effective placement of metal transducers for strong spin wave coupling. With an out-of-plane 3900 Oe bias field, the bandstop filter exhibits 55 dB maximum stopband rejection at a center frequency of 6.070 GHz, with 2 dB passband insertion loss and 37.8 dBm passband IIP3. By applying different bias fields, the stopband center frequency is tuned from 4 GHz to 8 GHz while maintaining more than 30 dB rejection. Incorporated with proper design of tunable compact electromagnet, this new filter design can provide attenuation of interferences appearing across the 5G and X-band spectrum.