| 摘要 |
A filter and a duplexer in which power loss due to the edge effect in resonator lines, is very effectively suppressed, which allow more reduction in overall size to be achieved, and which have desired filter characteristics, and a communication device including either or both of the filter and the duplexer. Three multiple spiral resonator stages are constructed by disposing three multiple spiral lines on the top surface of a dielectric substrate, and forming a ground electrode on the bottom surface thereof. If the first stage is set to be a right-handed spiral resonator, and the second and third stages are set to be left-handed spiral resonators, an attenuation pole is thereby created on the higher frequency side of a pass band.
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