Dual-Band Bandpass Filter With Controllable Bandwidths Using Two Coupling Paths
ABSTRACT This letter presents the designs of dual-band bandpass filters using two coupling paths to control the bandwidth of each passband. One coupling path only delivers signals at the upper passband frequency whereas the other one couple signals at both passbands. Utilizing this method, the two bandwidths can be adjusted. The filters make use of stub-loaded resonators and it is convenient to tune the passband frequencies. Therefore, both the frequency and bandwidth of each passband can be easily controlled. For demonstration purpose, two example filters are implemented with different bandwidths. The experimental results are presented to verify the proposed method.
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ABSTRACT: A novel quad-mode stepped impedance stub-loaded resonator is presented. The even-odd-mode method is applied twice to analyse the modal resonance characteristics due to its symmetry. All the four modes' equivalent circuits are quarter-wavelength stepped impedance resonators, so the proposed resonator has a compact size and higher harmonic frequencies. Stub-to-stub coupling is introduced to split two identical modes and produce two transmission zeros. A dual-band bandpass filter operating at 1.5 and 2.4 GHz is designed using the proposed resonator. The centre frequency and bandwidth of each passband can be controlled by tuning the corresponding physical dimensions, and a wide upper stopband is achieved. Finally, the designed filter was fabricated and measured, and the measured results have good agreement with the simulated ones.Electronics Letters 07/2014; 50(16):1145-1146. · 1.07 Impact Factor
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ABSTRACT: This paper presents a tri-stubs loaded multimode resonator (TSLMR) for designing dual-band bandpass filters. The TSLMR produces four spitting modes and the modal character is analyzed by using odd- and even-mode methods. A pair of even–odd modes is used to form the first passband, while another pair is used to produce the second passband. This resonator structure provides sufficient degrees of freedom to control the central frequencies and bandwidth of each passbands. Meanwhile, multi-transmission zeros are properly tuned for the rejections between the two passbands and in the upper stopband. A dual-band BPF operating at 1.57 and 3.5 GHz is designed and fabricated. Without a shorted structure and extra resonator, the measured filter shows good performance for both in band matching and outside rejections of the desired dual-passbands.Journal of Electromagnetic Waves and Applications 08/2014; 28(16). · 1.40 Impact Factor
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ABSTRACT: In this article, a novel compact dual-band bandpass filter with controllable bandwidths is presented. A set of central-loaded resonators are employed to generate dual band responses. Three coupled-capacitors, loaded at the corresponding voltage-zero points of the resonators, are utilized to control the coupling coefficients of two bands separately. Besides, two extra series capacitors, between feed lines and resonators, are adopted to simultaneously achieve the desired external quality factors of dual passbands. Thus, the bandwidths of the dual bands can be independently controlled. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1543–1546, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27665Microwave and Optical Technology Letters 07/2013; 55(7). · 0.59 Impact Factor