Designs of rectangular waveguide loaded with air-holes dielectric by topology optimization targeting cutoff frequency and bandwidth

Abstract

The design and topology optimization of rectangular waveguides loaded with porous dielectric has been proposed in this thesis. Numerical experiments on modal analysis of rectangular waveguides loaded with various structured porous dielectric made from longitudinal air tubes in lossless dielectric have been carried out by using the finite element method to investigate the modal dispersion characteristics and cutoff frequencies. The results of numerical experiments demonstrate that the dispersion characteristic and cutoff frequencies are depended on the filling factor which is defined as ratio of total area of air tubes to area of waveguide cross section. Thus, an equivalent model of a rectangular waveguide filled with porous dielectric, which is a dielectric-loaded rectangular waveguide of the same cross section with effective permittivity, has been proposed in this work. By using equivalent model, the design and topology optimization targeting cutoff frequency and bandwidth can be achieved effectively.