Patent ID: 7355494

Claim:
A band-pass filter comprising: a pair of resonators; and another resonator capacitively coupling the pair of resonators, said another resonator having frequency characteristics different from frequency characteristics of the pair of resonators, wherein: the pair of resonators are Î»a/4 resonators, the another resonator is a Î»b/2 resonator, wherein Î»b is set on a higher frequency side than Î»a and satisfies a relation of Î»a<Î»b<Î»aÃ—3, the pair of Î»a/4 resonators form a pass band corresponding to a Î»a wavelength and a pass band corresponding to a Î»aÃ—3 wavelength, and the Î»b/2 resonator forms a pass band corresponding to a Î»b wavelength which complements a pass band between the pass band corresponding to the Î»a wavelength and the pass band corresponding to the Î»aÃ—3 wavelength.