A Magnetically Tunable Bandpass Filter With High Out-of-Band Suppression

A new structure magnetically tunable bandpass filter with five stages was designed and realized in this article. Yttrium iron garnet/gadolinium gallium garnet/yttrium iron garnet (YIG/GGG/YIG) film multi-layer structure was set as the basic resonant unit, and the metal rectangular ring was added between the YIG/GGG/YIG film structures to improve the out-of-band suppression and adjust the bandwidth of the filter. Based on CST Studio Suite and experimental results, the parameters of the bandpass filter structure were determined. The filter center frequency can be tuned from 10 to 15 GHz as the bias magnetic field changing from 2850 to 5560 Oe, the out-of-band suppression was greater than 80 dBc, the insertion loss was less than 6.5 dB, and the bandwidth varied from 51 to 70 MHz in the whole working band range.