Title :
A novel microstrip filter structure consisting of transversal resonator array and its fully canonical bandpass filter design
Author :
Ohira, Masataka ; Kato, Toshiki ; Zhewang Ma
Author_Institution :
Grad. Sch. of Sci. & Eng., Saitama Univ., Saitama, Japan
Abstract :
A new and simple microstrip filter structure for a transversal array bandpass filter with multiple transmission zeros (TZs) is proposed, which is constructed by the parallel arrangement of even- and odd-mode half-wavelength resonators. The odd-mode resonators having open ends produce an intrinsic negative coupling with respect to the even-mode resonators with shorted ends, resulting in the cancellation of signals passing through parallel paths at stopbands. Thus, the proposed filter can generate multiple TZs with the control of external Q factors for multiple resonators, without using any couplings between adjacent/non-adjacent resonators. The resonant frequencies and the external Q factors required for resonators are synthesized with a coupling-matrix optimization, and then a fully canonical bandpass filter with 2-GHz center frequency, 6% bandwidth, and four TZs is designed. A very sharp roll-off response is achieved by TZs located at the passband edge, which is confirmed by both simulations and measurements.
Keywords :
Q-factor; band-pass filters; microstrip filters; microwave filters; optimisation; resonator filters; transversal filters; canonical bandpass filter design; coupling-matrix optimization; external Q factors; frequency 2 GHz; half-wavelength resonators; microstrip filter structure; nonadjacent resonators; odd-mode resonators; roll-off response; transmission zeros; transversal array bandpass filter; transversal resonator array; Band-pass filters; Couplings; Load modeling; RLC circuits; Resonant frequency; Resonator filters; Transversal filters; Bandpass filters; even mode; odd mode; transmission zeros; transversal array filters;
Conference_Titel :
Microwave Symposium (IMS), 2015 IEEE MTT-S International
Conference_Location :
Phoenix, AZ
DOI :
10.1109/MWSYM.2015.7166874