Dielectric filter having coupling electrodes for connecting resonator electrodes, and method of adjusting frequency characteristic of the filter

A tri-plate type dielectric filter, comprising:

• a dielectric substrate having top, bottom and four side surfaces;
• a plurality of resonator electrodes embedded in said dielectric substrate, each of said resonator electrodes having a first end and a second end, said resonator electrodes being juxtaposed and having said first ends spaced along a first side surface of said dielectric substrate;
• a ground conductor disposed on at least said first side surface and electrically connecting said first ends of said resonator electrodes to each other thereby short-circuiting said first ends of said resonator electrodes;
• and
• coupling means for capacitively connecting resonator electrodes to each other so as to provide capacitors between adjacent resonator electrodes, said coupling means comprising coupling electrodes formed within said dielectric substrate.