An efficient method of analysis of nonuniform transmission lines (NTL), based on wave digital model composed of cascaded unit elements and two‐port adaptors, is described. The proposed technique treats NTL as a cascade connection of equal‐length or equal‐delay uniform transmission lines. A simple algorithm for calculating transmission and input reflection coefficients is derived. Two application examples, proving the efficiency and response accuracy of the new technique, are given. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2150–2153, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22706

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Abstract-This paper introduces a theoretical analysis as well as a design example for bandpass filters (BPF) with a distinctive topology. Based on the analysis of simple two-port symmetrical lossless networks with a parallel structure, a method for obtaining normalized BPF prototypes with desired bandwidths was developed. These prototypes can be scaled to any central frequency and symmetrical real termination in the same way as conventional filters. It is also demonstrated that with a slight modification of the basic BPF prototypes, transmission zeros with controllable frequencies can be introduced in both the lower and the upper stopband region. Such modified prototypes are more convenient for the realization of printed filters than the basic BPF prototypes. The proposed filters have almost identical characteristics in the broad vicinity of the passband region either when composed of ideal lumped elements or of transmission lines (TLs). Due to its simplicity, the proposed concept could be applied for the realization of a printed BPF at a large variety of PCB types, substrates and practical design configurations. A microstrip BPF model is realized for the experimental verification of the presented theory. The measured and theoretical results show excellent agreement, confirming the proposed concept and the exactness of the methodology.

In this paper, a complete procedure is presented for the synthesis of a class of generalized Chebyshev filters with a maximum of four real transmission zeros of any multiplicity, having an equiripple characteristic in the passband and the stopband, and maximum selectivity. The frequencies of magnitude characteristic extreme values in the stopband are calculated in the closed form. The transmission zeros are obtained by solving a set of nonlinear equations. New formulas for orders of zeros of maximally selective filters are deduced, and these are very useful in the design procedure.

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The Equivalent Thevenin Source method combined with transfer parameter approach is employed to determine response of wave digital structure. This combination is a very efficient way for evaluating the scattering parameters of wave digital structures. A simple algorithm for coefficient calculation is derived. The described procedure can be implemented very effectively in any matrix oriented mathematical programs. One application example, proving the response accuracy of the new technique, is given.