Multiple-mode dielectric resonator and method of adjusting characteristic of the resonator

A multiple-mode dielectric resonator in which a combined dielectric block (2) formed of a plurality of dielectric elements (2a, 2b) combined into a crossed shape is used to cause three resonance modes along a plane defined by two of the dielectric elements (2a, 2b), and in which the resonant frequency of each mode is determined, or a multiple-mode dielectric resonator in which the degree of coupling between predetermined resonance modes is determined. If first and third resonance modes are two TM110 modes having different lines of symmetry of electric field distributions, and if a second mode is a TM111 mode, dielectric-cut portions (5a, 5b) are formed in the combined dielectric block, for example, at positions where the electric field distribution of the first resonance mode is concentrated while the electric field distributions of the second and third resonance modes are not concentrated, thereby selectively determining the resonant frequency of the first resonance mode.