JPS57148403A - Branching filter - Google Patents

Abstract

PURPOSE:To reduce size and weight, and to improve performance by constituting all of a low-pass and a high-pass notch filter, and BPFs in one body, and employing different coupling systems for branching and filtering output parts. CONSTITUTION:The resonance elements 11 and 12 of BPF parts 30 and 32 are a quarter as long as wavelengths of frequencies f2 and f1, respectively. The resonance element 13 of an additional resonator 31 as a high-pass notch filter is a quater as long as the wavelength of the frequency f1, and the resonance element 14 of an additional resonator part 33 as a low-pass notch filter is a quarter as long as the wavelength of the frequency f2. A coupling loop 19a couples an ouput contact tap 24 with the BPF part 32, and a coupling loop 19b couples the BPF part 32 with the additional resonance part 33. Coupling loops 20a and 20b couple an input contact tap 23 with the BPF parts 30 and 32. A coupling line 21a couples an output contact tap 22 with the BPF part 30, and a coupling line 21b couples the BPF part 30 with the additional resonance part 31.