| 摘要 |
PROBLEM TO BE SOLVED: To obtain a strip line filter that can prevent a pass band characteristic from being deteriorated by allowing an attenuation pole to be generated on one side of a low frequency or a high frequency of a pass band without the need for jumper connection for the input and output of the filter with a static capacitor, and to obtain a duplexer and a communication unit using the filter. SOLUTION: Resonator electrodes 11, 12, 13 are provided on an upper side of a dielectric board 1, ratios (W1/L1), (W3/L3) of electrode widths W1, W3 to electrode lengths L1, L3 of the 1st and final stages of the resonator electrodes 12, 13 are selected respectively to be the unity or more, and external lead electrodes 21, 23 are respectively connected to positions of the board 1 apart opposite to each other along the length direction from the center of the 1st and final stages of the resonator electrodes in the length direction. Thus, an attenuation pole is produced at the lower frequency side of the pass band.
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