| 摘要 |
PURPOSE:To improve insertion loss at a pass band area, by forming a parallel resonance circuit which resonates in the neighborhood of a serial resonance frequency means of floating capacitance of the serial resonance circuit provided between a transmission line and the earth, and of an inductance. CONSTITUTION:Two stages of resonators 31 and 32 are inserted between the transmission line 11-13 of lambda/4 and the earth via capacitances 21 and 22, and series resonance at frequencies f1 and f2 are generated by the capacitance 21 and the resonator 31, and the capacitance 22 and the resonator 32 respectively, and trap are performed at the frequencies f1 and f2. Also, phase adjusters 51 and 52, and amplifiers 41 and 42 are connected to the hot sides of the resonators 31 and 32 via the capacitances. The amplifiers 41 and 42, and the phase adjusters 51 and 52 are operated as negative resistances in the neighborhood of the resonance frequencies f1 and f2, and increase the Q of a circuit by supplying energy to the resonators 31 and 32. Furthermore, the floating capacitance 62 of the resonator 32 and the inductance 72 which parallel-resonate in the neighborhood of the frequency f2 are inserted between the transmission line and the earth. In such way, it is possible to improve the insertion loss between the frequencies f1 and f2.
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