8 pole high temperature superconductor microstrip dual band bandpass filter design

Dual-band filters are normally used for filtering two frequency bands that are not too close together. However, this paper presents a HTS dual-band bandpass filter that can be used to achieve isolation between two frequency bands that are only a few tens of MHz apart. Transmission zeros are placed in between the two frequency bands using electromagnetic coupling between non-adjacent resonators which result in high isolation between the two bands. The simulation and experimental results of a High Temperature Superconductor dual-band bandpass filter with very narrow bandwidth will be presented here.