Dielectric filter having coupling amount adjusting patterns

Abstract

A dielectric filter includes a unitary dielectric block formed of a uniform, single dielectric material and having electrically conductive metallized patterns formed on front, rear and lateral walls, and on an outer bottom surface thereof. A plurality of coaxial dielectric resonators each including an open end and a central conductor are longitudinally arranged along the center of a top surface of the block and are spaced apart a predetermined distance. Frequency adjusting patterns are formed on the top surface of the block, each frequency adjusting pattern extending around an open end of a respective one of the resonators. Coupling amount adjusting patterns are also disposed on the top surface of the block, each connected to the front and rear walls and disposed between adjacent ones of the frequency adjusting patterns. At least one additional coupling amount adjusting pattern is disposed on the top surface of the block. The additional coupling amount adjusting pattern has a first end mechanically connected to the front wall and a second end capacitively coupled to the rear wall, a gap being provided between the second end and the rear wall. The additional coupling amount adjusting pattern determines a pre-adjusted maximum coupling amount larger than a coupling amount of the plurality of coupling amount adjusting patterns which are connected to the front and rear walls.