HIGH-FREQUENCY FILTER

PROBLEM TO BE SOLVED: To provide an improved high-frequency filter so as to be kept small is size even if a load Q (QL value) is comparatively small. SOLUTION: For example, when (n) is 3, a band-elimination filter 1 is equipped with reentrant cylindrical resonators 241, 243, and 245 mounted on the recesses of the outer wall of the outer conductor 12 of a rectangular coaxial tube. A recess is provided to a part of the outer wall of the outer conductor 12 opposed to the reentrant cylindrical resonator 241, and a reentrant cylindrical resonator 242 is mounted on the recess. The part where the resonator 242 is mounted is of the electrically same phase point with the resonator 241, a load Q (QL value) at the part is larger than that when only the resonator 241 is provided, and also a gap gets larger, so that the band-elimination filter 1 is capable of having an improved withstand power. A resonator interval can be set at λo/4 or so. The other resonators 243 and 245 are formed the same as the resonator 241.