Rigorous Design and Efficient Optimization of Quarter-wave Transformers in Metallic Circular Waveguides Using the Mode-matching Method and the Genetic Algorithm

This paper presents an approach for the design and optimization of pseudo-gradual transitions in circular waveguides using the genetic algorithm (GA). The characterization of these transitions is carried out by the mode-matching method. This method, associated with the generalized scattering matrix technique, leads to determine the reflection coefficient on the useful band of the studied structures and to observe their frequential behavior. The GA is employed to optimize the choice of geometrical parameters by minimizing a cost function, corresponding to the maximum magnitude of the reflection coefficient in the band. The selection of the most relevant parameters allowed an improvement of the performances for the optimized components. Results of optimization are given for both two and four-section transformers.