High temperature superconductor staggered resonator array bandpass filter

Abstract

A bandpass filter comprises multiple side-coupled strip line resonators wherein the resonators are staggered or offset with respect to their nearest neighbors by substantially 1/4 wavelength or less. In the preferred embodiment, the strip line bandpass filter structure has substantially parallel resonators arrayed with substantially constant spacing between the resonators with 1/4 wavelength overlap or less. Generally, the amount of stagger between nearest neighbors is reduced for resonators toward the center of the filter. Coupling between resonators is controlled by varying the relative amount of stagger between resonators. The resonators may be formed from normal metal or superconducting materials, such as YBCO or thallium containing superconductors. A strip line structure may be formed by utilizing two mirror structures each comprising a substrate having a ground plane and a patterned staggered resonator array formed on the substrate on a side opposite the ground plane. In another aspect of this invention, a ground plane tuning system utilizes a variable positioning member. The member is moveable towards and away from the resonator array, resulting in tuning. In the preferred embodiment, a threaded plug mates with a threaded housing opening, permitting tuning by rotation of the insert.