High Selectivity Single Wideband and Quad-Band HTS Filters Using Novel Quad-Mode Resonators With Self-Coupled Structure

Junjie Zhang, Qing Liu, De-Wei Zhang, Ying Qu
2021 IEEE Access  
This paper presents improved quad-mode resonators based on the open/short-end load of the center stub, which introduces the self-coupled structure. Compared with the traditional stub-loaded stepped impedance resonator (SLSIR), the proposed quad-mode resonators can significantly reduce the circuit size and further increase the design freedom. First of all, a comprehensive theoretical analysis is performed to infer the resonant characteristics of the proposed resonator. Then, two design
more » ... based on different center loads of the resonator were demonstrated to verify the feasibility of the design method. First, a prototype of a wideband high temperature superconducting (HTS) filter with an FBW of 89% is proposed, whose center frequency (CF) can be flexibly controlled. Next, a quad-band HTS filter using different central stub load is proposed, which centered at 1.20, 2.52, 3.51, 4.44 GHz with the 3-dB FBW of 4.8%, 3.96%, 3.97% and 2.2%, respectively. The internal and external coupling mechanisms are also carefully studied to meet the specified requirements. The two prototypes proposed in this paper both have the advantages of compact size, ultra-low insertion loss and steep suppressed skirts. In addition, the measured results are in good agreement with the EM full-wave simulated results. INDEX TERMS Bandpass filter (BPF), wideband, quad-band, high temperature superconducting (HTS), quad-mode.
doi:10.1109/access.2021.3097541 fatcat:dg62e2xhmvd7ppjmnntjifpwau