HTS dual-band bandpass filters using stub-loaded hair-pin resonators for mobile communication systems

• We have developed a HTS five-pole dual-band bandpass filter using stub-loaded hair-pin resonators.
• The proposed dual-band BPF can independently control of the center frequency.
• Flexibly adjustment of the bandwidth can be achieved by the H-shaped waveguide.
• The proposed BPF is evaluated by simulation and measurement with good agreement.

A HTS dual-band bandpass filter is developed to obtain sharp-cut off characteristics for mobile communication systems. The filter is composed of five stub-loaded hair-pin resonators with H-shaped waveguides between them. The main advantage of the proposed filter is to allow independent control of the center frequency of the first and second bands. The bandwidths can be flexibly adjusted using the H-shaped waveguide. An electromagnetic simulator was used to design and analyze the filter, which have a 3.5-GHz center frequency and a 70-MHz (2%) bandwidth for the first band and a 5.0-GHz center frequency and a 100-MHz (2%) bandwidth for the second band. The filter was fabricated using YBa2Cu3Oy thin film on an Al2O3 substrate. Ground plane was fabricated using Au thin film. The measured frequency responses of the filter tally well with the simulated ones.