A design environment for the automated optimisation of low cross-polarisation horn antennas

[摘要] ENGLISH ABSTRACT: The aggressive space mapping algorithm is used in this project for the optimisation of electromagneticstructures. This technique combines the use of fast, less accurate models with moretime-consuming, high precision models in the optimisation of a design.MATLAB's technical computing environment possesses powerful tools for optimisation as wellas the graphical representation and mathematical post-processing of data. A software interface,which uses Visual Basic for Applications, is created between MATLAB and the electromagneticsolvers, CST Microwave Studio and μWave Wizard, that are used for the fine and coarse modelcalculations. The interface enables the direct interchange of data, which allows MATLAB to controlthe optimisation for the automation of the design process.The optimisation of a microwave coaxial resonator with input coupling is used to demonstrate thedesign environment. An accurate equivalent circuit model is available to describe the problem.The space mapping optimisation of this structure works well, with a significant improvement inthe efficiency of the optimisation when compared to standard optimisation techniques.Multimode horn antennas are of interest for use as feeds in radio-astronomy telescope systems.The design of a stepped circular horn antenna in the space mapping design environment is presented.The horn's radiation pattern is optimised for low cross-polarisation. This structure is muchmore complex to model than the resonator example. The generalised scattering matrix representationis used in the coarse model description. The far-fields are calculated from the aperture fieldsby means of the Fast Fourier Transform. Various tests confirm that the optimisation is steeredin the right direction as long as the coarse model response follows the trend of the fine modelresponse over the optimisation space.The presented design environment is a powerful tool for the automation of the design of electromagneticstructures.

[发布机构] Stellenbosch University