Compact quadruple-mode resonator for wideband bandpass filter design

• Published in: IET microwaves, antennas & propagation Vol. 8; no. 2; pp. 67 - 72
• Main Authors: Lee, Ker Chia, Su, Hieng Tiong, Haldar, Manas K
• Format: Journal Article
• Language: English
• Published: Stevenage The Institution of Engineering and Technology 01.01.2014; Institution of Engineering and Technology; The Institution of Engineering & Technology
• Subjects: Applied sciences; Approximation; Bandpass filters; Bandwidth; band‐pass filters; branch‐lines; Circuit properties; compact design; compact quadruple‐mode resonator; Electric, optical and optoelectronic circuits; Electronic circuits; Electronics; Exact sciences and technology; Frequency filters; Mathematical analysis; Noise levels; Oscillators, resonators, synthetizers; Resonant frequencies; resonator filters; Resonators; square open‐loop resonator; Wideband; wideband bandpass filter design; resonator filters; compact design; compact quadruple-mode resonator; band-pass filters; wideband bandpass filter design; square open-loop resonator; branch-lines; Resonator; Wide band circuit; Resonance frequency; Analytical method; Open loop; Band pass filter; Compact design
• ISSN: 1751-8725; 1751-8733; 1751-8733
• DOI: 10.1049/iet-map.2013.0021

This study presents the realisation of a wideband bandpass filter using a novel compact quadruple-mode resonator. The quadruple-mode resonator, which is evolved from the square open-loop resonator, is an interesting structure for a compact design. The resonator has two odd and two even mode resonant frequencies whose approximate analytical expressions are derived. For a wide bandwidth filter, three short branch-lines are introduced to the resonator in order to widen the separation between the resonant frequencies. A filter with a 3 dB fractional bandwidth of 96.0% is demonstrated. Simulated and measured results are in good agreement.