Novel Centrally Loaded Resonators and Their Applications to Bandpass Filters

• Published in: IEEE transactions on microwave theory and techniques Vol. 56; no. 4; pp. 913 - 921
• Main Authors: Xiu Yin Zhang, Xiu Yin Zhang, Quan Xue, Quan Xue
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.04.2008; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; Band pass filters; Bandpass filters; centrally loaded resonators; Circuit properties; Design engineering; Dual band; dual-band filters; Electric, optical and optoelectronic circuits; Electronic circuits; Electronics; Exact sciences and technology; Frequency filters; harmonic suppression; Harmonics suppression; Microwave filters; Microwaves; Oscillators, resonators, synthetizers; Passband; Predictive models; Resonance; Resonant frequencies; Resonant frequency; Resonator filters; Resonators; Simulation; Tunable circuits and devices; Tunable filters; Performance evaluation; Tunable circuit; Resonator; tunable filters; harmonic suppression; Bandpass filters; dual-band filters; Implementation; Harmonics suppression; Simulation; centrally loaded resonators; Tunable filter; Resonance frequency; Band pass filter; Band stop filter; Passband
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.2008.919648

This paper presents several novel centrally loaded resonators and their applications to various types of bandpass filters. Based on the theoretical analysis, it is found that the even- mode resonance of the proposed resonators can be conveniently controlled without affecting the responses at the odd-mode resonant frequencies. Benefiting from this feature, the resonator can be utilized to design not only harmonic-suppressed bandpass filters and dual-band bandpass filters but also tunable bandpass filters. The tunable filter offers a fixed passband and a tunable one. The center frequency of the upper passband can be electrically tuned, whereas the performance of the lower one is maintained constant. To demonstrate these applications, four filters using the proposed resonators are implemented. The experiments verify the theoretical predictions and simulations.