MULTIBAND BAND-PASS FILTER

PROBLEM TO BE SOLVED: To provide a dual-band band-pass filter in which the degree of freedom in designing a center frequency, a bandwidth, and input/output matching in each of two or more pass bands is improved and which can be made small-sized further.SOLUTION: In a multiband band-pass filter, a symmetric surface A-B of a stab 11 of a dual-band resonator which is structured by adding the stab 11 to a half-wavelength resonator 10 forms an electric/magnetic wall. The dual-band band-pass filter is operated in two frequency bands by odd mode resonance and even mode resonance. The half-wavelength resonator 10 becomes a resonator based on an odd mode, and the half-wavelength resonator and the stab become a resonator based on an even mode. A resonator length is adjusted so as to resonate the odd mode at a low frequency side and to resonate the even mode at a high frequency side. Otherwise, the odd mode can be resonated at the high frequency side and the even mode can be resonated at the low frequency side.