HTS selective bandstop filter for radio astronomy applications

A six-pole High Temperature Superconducting (HTS) microstrip bandstop filter operating at S band is presented in this paper. The filter has applications in radio astronomy receivers. The zig-zag loop resonator and a meandering transmission line are developed to reduce the parasitic effect of the direct resonator-to-resonator coupling and to reduce the size of the filter structure. An elliptical behavior in the frequency characteristic is introduced by designing the resonators to resonate at asynchronous frequencies and also by varying the inter resonator path length.