Dual mode band pass filter

摘要

A dual mode band pass filter is constructed to be very compact and such that the coupling strength and bandwidth can be easily and widely adjusted while maintaining sufficient freedom of design. A metal film for forming a resonator is arranged on a first main surface of a dielectric body or at a certain height in the dielectric body. At least one ground electrode is arranged such that the ground electrode is opposed to the metal film via the dielectric body. The metal film is connected to input/output coupling circuits. In the region where the metal film is opposed to the ground electrode, two portions are partially provided. Each of these two portions has a relative permittivity that is different from the relative permittivity of the remaining portion, in order to couple two resonance modes.