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.
