A wide stopband band-pass HTS filter with staggered resonators

• We design and fabricate an HTS band-pass filter with a very wide stopband.
• The filter is designed using a method of staggered resonant modes.
• A new topology of resonator suitable for this method is proposed.
• The stopband is up to 26f0 with rejection better than 60 dB.

This letter presents a novel high-temperature superconducting (HTS) band-pass filter with a very wide stopband using the method of staggered resonant modes, that is, dissimilar resonators with the same fundamental frequency but different harmonic frequencies. A new type of resonator that is suitable for this method is proposed. The design rules and design process of this method are analyzed in detail. A six-pole HTS band-pass filter centered at 500 MHz with a 2 MHz bandwidth is successfully designed and fabricated. Measured out-of-band rejection is better than 60 dB and can reach up to 13 GHz, which is about 26 times the fundamental frequency.