A closed slot-line resonator filter

A microwave bandpass filter made from three-dimensional (3-D) slot-line resonators is described. This structure readily lent itself to the design and realization of a 16-pole filter. By concentrating the losses on the resonant element, very high Q can be achieved by using low surface resistance material, such as high temperature superconductor, for the slot-line resonator. The filter is five to ten times smaller than previous generation 3-D filters made using high temperature superconductors.