Novel Dual-Mode Dual-Band Filters Using Coplanar-Waveguide-Fed Ring Resonators

• Published in: IEEE transactions on microwave theory and techniques Vol. 55; no. 10; pp. 2183 - 2190
• Main Authors: Xiu Yin Zhang, Xiu Yin Zhang, Quan Xue, Quan Xue
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.10.2007; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; Band pass filters; Bandpass filter; Bandwidth; Circuit properties; compact size; Degrees of freedom; Dual band; dual mode; Electric, optical and optoelectronic circuits; Electronic circuits; Electronics; Exact sciences and technology; Feeding; feeding structure; Feeds; Frequency; Frequency filters; Joining; Mathematical analysis; Microstrip resonators; Microwave circuits, microwave integrated circuits, microwave transmission lines, submillimeter wave circuits; Microwaves; Optical ring resonators; Oscillators, resonators, synthetizers; Passband; Q factor; Quality factor; Resonator filters; Resonators; Specifications; Tunable circuit; Waveguide resonator; Q factor; dual band; dual mode; compact size; feeding structure; Compact design; Specification; Selectivity; Microstrip resonator; Implementation; Mode filter; Bandpass filter; Ring resonator; Coupling coefficient; Antenna feeds; Band pass filter; Coplanar waveguides; Passband
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.2007.906501

This paper presents a novel approach for designing dual-mode dual-band bandpass filters with independently controlled center frequencies and bandwidths. Two microstrip perturbed ring resonators are employed to obtain dual-mode dual-band responses. Novel feeding structures are introduced to simultaneously feed the ring resonators and conveniently control the coupling strength between resonators and feeding lines, resulting in a wide tunable range of external quality factors. Two kinds of filter configurations with compact size are proposed. Both of them provide sufficient degrees of freedom to satisfy various requirements of external qualify factors and coupling coefficients at both passbands. Therefore, the center frequencies and fractional bandwidths of both passbands can be independently tuned to desired specifications within a wide range. To verify the proposed method, four filters are implemented. The measured results exhibit dual-mode dual-band bandpass responses with high selectivity.