Miniaturized Multiband HTS Bandpass Filter Design Using a Single-Perturbed Multimode Resonator With Multitransmission Zeros.

This paper presents a miniaturized quint-band hightemperature superconducting (HTS) bandpass filter (BPF) based on a single-perturbed multimode resonator (PMMR). By properly adjusting the lengths and the position of the perturbation line in a PMMR, the intrinsic resonance modes can be controlled, which is advantageous for multiband design. The source-load coupling, spurlines, and matching stubs on feedlines are introduced to improve impedance matching and to generate multitransmission zeros, so that enhanced isolation and harmonics suppression can be realized. A low insertion loss (IL) within each band is obtained by using an HTS technology. The filter is fabricated on an MgO substrate with the YBCO thin films, and measured at the temperature of 77 K. The passband measurement is consistent with the simulation, which verifies five passbands located at 0.56, 1.52, 3.8, 4.7, and 5.3 GHz, respectively. A low-measured IL with less than 0.2 dB level is obtained due to the application of a superconducting technology. The proposed HTS BPF owns the great merits of a simple structure, a miniature size (0.008λg 2), an enhanced upper stopband, and a low IL. [ABSTRACT FROM AUTHOR]