Tapping" for both I/O and interstage couplings of the resonator is the key concept here because a resulting open-ended resonator makes shunt open stubs which give anti-resonance near the center frequency. Multiple attenuation poles appear near the center frequency, namely, close to the passband. A BPF is designed on the basis of the general filter theory with a narrow band approximation. An experiment is carried out to confirm the concept by using a coplanar structure. The expected bandpass characteristics with multiple attenuation poles have been obtained by the novel BPF designed by the present concept." />

Design of a Bandpass Filter with Multiple Attenuation Poles Based on Tapped Resonators

Kouji WADA  Ikuo AWAI  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E82-C   No.7   pp.1116-1122
Publication Date: 1999/07/25
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Microwave and Millimeter Wave Technology)
Category: Passive Devices and Circuits
Keyword: 
multiple attenuation poles,  half-wavelength resonator,  tap-coupling,  bandpass filter,  filter design,  

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Summary: 
An intrinsic property of a tapped resonator is elucidated here, and a novel bandpass filter (BPF) with improved skirt characteristics based on a tapped half-wavelength resonator is proposed by this intrinsic property. "Tapping" for both I/O and interstage couplings of the resonator is the key concept here because a resulting open-ended resonator makes shunt open stubs which give anti-resonance near the center frequency. Multiple attenuation poles appear near the center frequency, namely, close to the passband. A BPF is designed on the basis of the general filter theory with a narrow band approximation. An experiment is carried out to confirm the concept by using a coplanar structure. The expected bandpass characteristics with multiple attenuation poles have been obtained by the novel BPF designed by the present concept.