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A dual-band substrate integrated waveguide (SIW) filter is presented in this article. The dual-band cross-coupled design procedure is based on the frequency transformation from the normalized frequency domain to the actual frequency domain, which can calculate the coupling coefficients and the external quality factors analytically. The cross-coupled SIW filter has the flexibility to achieve different kinds of filtering characteristics with the same coupling structure. To validate the method, a practical SIW dual-band filter operating at 5.85-5.95 GHz and 6.05-6.15 GHz is designed and fabricated. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1609-1612, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26908 [ABSTRACT FROM AUTHOR]

A wideband cross coupled bandpass filter making use of square split-ring resonator (SRR) defected ground structure (DGS) and parallel microstrip feed line is presented in this paper. The coupling between a pair of SRR DGS is much larger than that of the conventional SRR, which is fully investigated and applied to the design of wideband cross coupled filter. By extracting the coupling coefficient of various coupling structures and external quality factors of various feed structures, a SRR DGS four-pole filter with center frequency of 2.2 GHz and bandwidth of 20% is designed and fabricated. [ABSTRACT FROM AUTHOR]

A novel bandpass filter with two dual-mode cavities based on the substrate integrated waveguide (SIW) is presented. By making use of the inductive discontinuities in an SIW cavity, two degenerate modes can be excited. Due to the phase difference of the two modes in each cavity, two transmission zeros on each side of the passband are created, so the out-of-band rejection of the filter is significantly improved. An SIW dual-mode filter with a center frequency of 12 GHz has been fabricated and measured. The experimental results agree well with the simulation results. [ABSTRACT FROM AUTHOR]

This paper presents a novel dual-band banpass filter using microstrip open-loop resonators. A new microstrip unit of dual-band bandpass filter is introduced, which can be used as unit element of duan-band filter design. The two open-loop resonators are treated as passband resonator and stopband resonator in analysis, respectively. A five-pole C-band dual-band bandpsss filter has been designed and fabricated. The measured results show a good agreement with the simulated results. [ABSTRACT FROM AUTHOR]

A novel design method of dual-band and tri-band band-pass filters is proposed in this paper. A compact loaded open-loop resonator(LOLR) structure is introduced. The resonant frequency response of the resonator is described in detail. A dual-band filter and a tri-band filter are designed with the LOLRs. 0° feed structures are applied to improve the selectivity of the proposed filters. The measurements of the filters are in good agreement with the simulated results. [ABSTRACT FROM AUTHOR]

A design method of tubular filter based on S-parameter curve-fitting method is presented, and a synthesis process from low-pass prototype to tubular band-pass filter is also analyzed. By using step-increasing theory, the curve-fitting process for designing tubular filter is proposed in particular. This method not only makes sure that the values of serial elements are accurate in each simulated process, but also reduces the factors which influence the values of shunted elements, and decreases the complexity in determining the element size. [ABSTRACT FROM AUTHOR]

A novel type of dual-band microstrip structure and its equivalent circuit are investigated, which is composed of defected split-ring resonator and interdigital capacitor. The influence of design parameters on the frequency characteristics is discussed, then a dual-band microstrip filter, which has two passbands of 1.8–2.5 GHz and 5.5–5.9 GHz with a transmission zero, is designed and fabricated. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2104–2106, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22673 [ABSTRACT FROM AUTHOR]