Dielectric filter with inductive coupling electrodes formed on an

Abstract

The present invention relates to a radio frequency filter, comprising a block(1) of a dielectric agent and an insulation sheet (2) attached to a side surface thereof. From the top surface of the block to the undersurface, at least two holes (3,4,5) coated with a conductive agent extend. At least most of the surface of the body, with the exception of one side surface, as well as the surfaces of the holes have been coated with a conductive agent, whereby a transmission line resonator is produced for each hole. The surface of the insulation sheet (2) fixed against the uncoated side surface but not facing the block has also been coated with a conductive agent. The coupling pattern formed by the metallic electrodes is located between the opposite surfaces. The unevenness of the surfaces placed against each other and the defects in adjusting the pieces cause great divergence in the response curves of the filters. This can be reduced in that prior to attaching the insulation sheet (2) part (14,15,16,17,115) of the electrodes of the coupling pattern have been arranged on the uncoated side surface of the insulation sheet (2) and the rest (7,8,9,10,11,12,13,114) of the electrodes of the coupling pattern have been arranged on the other side surface of the body.