PURPOSE: To obtain a coaxial type filter of simple structure which has a wide stopping band and high-frequency suppression characteristics by combining resonators which have uniform characteristic impedance of a line with a resonator which varies in characteristic impedance stepwise.
CONSTITUTION: The resonators 44 and 46 which have uniform characteristic impedance of the line are combined with the resonator SIR45 which varies in the characteristic impedance of the line stepwise. The spurious resonance frequency of the uniform line can not be varied and is odd times as high as a basic frequency, but the SIR45 varies the spurious resonance frequency optionally by its impedance ratio (characteristic impedance of open-side line/characteristic impedance of short-circuit side line). Thus, the filter consisting of resonators having different spurious resonance frequencies although the basic frequency is coincident is atthenuated sufficiently in frequency except the basic frequency, so the filter which as a passing band only at the basic frequency and a wide stopping band is realized.
| JP3480014 | SURFACE MOUNT TYPE DIELECTRIC FILTER |
MAKIMOTO MITSUO
YAMASHITA SADAHIKO
