Nicolas Boutheiller

A two zero fourth order microwave waveguide filter using a simple rectangular quadruple-mode cavity

In order to reduce the size of microwave waveguide filters, triple and quadruple mode filters in circular waveguide have been investigated intensively. However, the research for such filters in rectangular waveguide is still poor and the rare trials have led to complicated sensible structures with loaded cavities. This paper describes a fourth order filter with two transmission zeroes obtained with only one basic rectangular cavity and two irises. Neither coupling nor tuning screws are needed. The analysis at the discontinuities is performed by the moment method. The synthesis lies on an optimization method based on the genetic algorithm.

Genetic algorithm based CAD of microwave waveguide filters with resonating bend

An accurate and efficient CAD tool is presented and aims at designing evanescent mode waveguide filters with resonating mode in the uniform bend. It arises from mode-matching method suited in this case to the bend of a waveguide. The scattering parameters of the whole structure are computed and compared to those of experimental prototypes. The innovation rests in a specific propagation property of resonating modes in the bend allowing replacing the usual dielectric inserts. An optimization based on a modified genetic algorithm is added to this CAD tool for improving the design efficiency. The calculations exhibit good convergence behavior with the required specifications.

Multi-mode analysis of filters using multi-sections iris. Genetic optimization and realization of filters with low dimensions and transmission zeros

RésuméNous présentons une méthode de recherche de nouvelles structures de filtrage hyperfréquence en guide d’ondes. Une technique d’analyse électromagnétique est exposée. Celle-ci permet de caractériser toute structure composée de portions rectilignes de guide d’ondes rectangulaire dont les surfaces ouvertes aux extrémités se recouvrent partiellement. Les surfaces non partagées sont supposées parfaitement conductrices. Chaque portion de guide d’ondes est considérée emplie de diélectrique homogène isotrope. Les éléments de base de ces éléments filtrants sont alors des discontinuités de dimensions multi-sections mais aussi des discontinuités diélectriques. Cette étude est basée sur la détermination de la matrice de répartition généralisée ayant un nombre de modes important. Le couplage de deux modes permettra de réaliser un zéro de transmission et par-là d’accroître la sélectivité de tels filtres. La prise en compte d’un grand nombre de modes permet aussi de diminuer considérablement les dimensions. Nous déterminons donc la matrice S multimodale généralisée d’une multisections à l’aide de la méthode des moments. Ces résultats mis sous forme synthétique (matrice) nous permettent de synthétiser et de réaliser des structures de filtrage efficaces et de faibles dimensions. Une structure de filtrage originale, optimisée à l’aide d’un algorithme génétique, valide cette étude électromagnétique.AbstractWe present the design and the development of a research method for new microwave waveguide filtering structures with low dimensions and tranmission zeros. An electromagnetic analysis technique is exposed. It permits to characterize all structures composed of rectilinear pieces of rectangular waveguide whose opened areas at the extremities partially overlap. Non shared areas are supposed perfectly conductive and every piece of waveguide is filled with homogeneous isotropic dielectric material. Basic elements are size discontinuities and dielectric discontinuities. We determine the generalized scattering matrix using multimode analysis. Using a lot of modes leads also to reduce dimensions. Coupling of two modes leads to the realization of a zero transmission and improves the selectivity of the filters. Optimization is made using genetic algorithm. In addition to theory, the measured response of a filter is presented and valids the proposed filter concept.We present the design and the development of a research method for new microwave waveguide filtering structures with low dimensions and tranmission zeros. An electromagnetic analysis technique is exposed. It permits to characterize all structures composed of rectilinear pieces of rectangular waveguide whose opened areas at the extremities partially overlap. Non shared areas are supposed perfectly conductive and every piece of waveguide is filled with homogeneous isotropic dielectric material. Basic elements are size discontinuities and dielectric discontinuities. We determine the generalized scattering matrix using multimode analysis. Using a lot of modes leads also to reduce dimensions. Coupling of two modes leads to the realization of a zero transmission and improves the selectivity of the filters. Optimization is made using genetic algorithm. In addition to theory, the measured response of a filter is presented and valids the proposed filter concept.