Tunable Bandpass and Bandstop Filters Based on Dual-Band Combline Structures

• Published in: IEEE transactions on microwave theory and techniques Vol. 58; no. 12; pp. 3710 - 3719
• Main Authors: Abunjaileh, A I, Hunter, I C
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.12.2010; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; Bandpass; Bandstop filters; Bandwidth; Chebyshev approximation; Circuit design; Circuit properties; Combline filters; Construction; Dual band; Electric, optical and optoelectronic circuits; Electronic circuits; Electronics; Exact sciences and technology; Frequency filters; Microwave circuits, microwave integrated circuits, microwave transmission lines, submillimeter wave circuits; microwave filters; Microwaves; Passband; Prototypes; Resonant frequency; tunable filters; Tuning; Tunable circuit; Band structure; tunable filters; Prototype; Comb configuration; Microwave filter; Tuning; Multi-band circuit; Tunable filter; Band pass filter; microwave filters; Band stop filter; Combline filters; Passband
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.2010.2083950

New methods for the design of tunable combline bandpass and bandstop filters are presented. The first part of this paper presents a tunable bandstop filter designed using a dual-band circuit with wide passband and integrated narrow stopband. A prototype has been constructed and measured results shows that the bandwidth remained constant at 30 MHz as the filter was tuned from 3.22 GHz to 3.66 GHz. The second part of this paper presents a tunable bandpass filter designed using a dual-band circuit with both wide passband and stopband. The response corresponds to two narrow passbands, where the lower passband bandwidth and center frequency can be tuned. A prototype has been constructed and measured results demonstrate wide centre frequency tuning range and over 300% bandwidth tuning without the need for coupling adjustment.