Robert Boschgmbh

Arno Baumfalk

Heinz Chaloupka

Serguei Kolesov

The pass band filter has planar ring resonators arranged in pairs partly side-by-side and partly one above the other and a housing cover for each resonator. Each resonator includes a respective substrate provided with upper and lower conductive layers of high temperature superconductor material on respective opposite sides of the corresponding substrate, so that each planar ring resonator is operable in an edge-current-free TM010-oscillator mode. A respective coupling hole of radius r.sub.i is provided in the lower conductive layer (3) of each resonator and the lower conductive layers of both resonators in each pair face each other so that both resonators are coupled. Each housing cover has a respective truncated cone-shaped step ring (20) having a corresponding inner housing cover radius (r.sub.G). The radius ratio r.sub.i /r.sub.a (r.sub.a is the radius of the circular upper conductive layer) and the inner housing cover radius for each resonator are selected so that resonance frequencies of undesired oscillator modes of the resonators are shifted up to about 22% relative to the resonance frequency of the edge-current-free TM010-oscillator mode.

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Munich, Georgia

Arno Baumfalk