Resonator, filter, duplexer, and high-frequency circuit apparatus

摘要

In a resonator having a dielectric member and an electrode formed on the dielectric member, a displacement area (D area) having a high vertical electric field component, and a short or steady area (S area) having a vertical electric field component of zero or close to zero are provided in an interface between the dielectric member and the electrode. A single-layer conductive film divided into portions is formed in the D area or on the side surfaces of the dielectric member, and a multilayer thin-film electrode is formed in the S area or on the end faces of the dielectric member. Conductive thin films of the multilayer thin-film electrode are alternately connected to the single-layer conductive film portions. In-phase currents having the same amplitude flow to the conductive thin films of the multilayer thin-film electrode in the S area in radial direction with respect to the axis of symmetry, thus achieving low-loss operation of the multilayer thin-film electrode in the S area.