Coaxial filter having a plurality of resonators each having a bottomed cylinder

摘要

In a coaxial filter arrangement having a plurality of coaxial resonators each having a bottomed metallic cylinder interposed between a dielectric plate and one end of a center conductor of each resonator, the peripheral wall portion of the metallic cylinder is received in the bore of an outer conductor having an open end and a closed end connected to the other end of the center conductor. In one embodiment, the bottom of the metallic cylinder has a convex portion at its center so that the bottom center projects outwardly. In another embodiment, an annular metallic member is interposed between the dielectric plate and the outer surface of the flat bottom of the metallic cylinder. Since the distance between bottoms of metallic cylinders of adjacent resonators is made large with this arrangement, influence due to leakage flux of electromagnetic field is small, while stray capacitance is negliegibly small, thereby providing a filter having high performance and low loss.