Synthesis methods for multi-band coupled resonator filters

[摘要] ENGLISH ABSTRACT: In this dissertation a number of techniques to design multi-band filters, with specific focus on coupled resonatorimplementations, is presented. Multi-band transfer functions are constructed from single-band transferfunctions using frequency mapping methods. A general class of rational mapping functions is presentedthat can accommodate arbitrary bandwidth specifications. Multi-band circuits are synthesised directly frommulti-band transfer functions and are obtained by applying reactance transformations to single-band prototypecircuits. For the direct synthesis of multi-band filters from multi-band transfer functions coupling matrixsynthesis methods are employed. The circuits that result from matrix synthesis methods tend to have topologiesthat are undesirable from a practical perspective and must be simplified using rotations of the couplingmatrix. The synthesis of multi-band filters through reactance transformations is both simple and result in filtersthat have practical topologies for realisation as coupled resonator circuits. Multiple filters are designed usingdifferent design methodologies and different transmission line technologies to illustrate the various designpossibilities. The designs include both all-pole and cross-coupled filters and employ single-layer stripline,multi-layer stripline as well as coaxial resonators as transmission line technologies for the implementations.

[发布机构] Stellenbosch University