Novel Spatial Domain Integral Equation Formulation for the Analysis of Rectangular Waveguide Steps Close to Arbitrarily Shaped Dielectric and/or Conducting Posts

• Published in: Radio science 2018-04, Vol.53 (4), p.406-419
• Main Authors: Quesada Pereira, F. D., Gómez Molina, C., Alvarez Melcon, A., Boria, V. E., Guglielmi, M.
• Format: Article
• Language: English
• Subjects: Cavity resonators; Computer simulation; Dielectrics; Electric filters; Equivalence; Filters; Green's functions; Ground plane; integral equation formulation; Integral equations; Method of Moments; Numerical methods; Parallel plates; rectangular waveguide microwave components; Software packages; Waveguide discontinuity
• ISSN: 0048-6604; 1944-799X
• DOI: 10.1002/2017RS006429

In this paper, a novel integral equation formulation expressed in the spatial domain is proposed for the analysis of rectangular waveguide step discontinuities. The important novelty of the proposed formulation is that which allows to easily take into account the electrical influence of a given number of arbitrarily shaped conducting and dielectric posts placed close to the waveguide discontinuity. For the sake of simplicity, and without loss of generality, the presented integral equation has been particularized and solved for inductive rectangular waveguide geometry. In this case, the integral equation mixed‐potentials kernel is written in terms of parallel plate Green's functions with an additional ground plane located on the waveguide step. Therefore, the unknowns of the problem are reduced to an equivalent magnetic surface current on the step aperture and equivalent magnetic and electric surface currents on the dielectric and conducting posts close to the discontinuity. The numerical solution of the final integral equation is efficiently computed after the application of acceleration techniques for the slowly convergent series representing the Green's functions of the problem. The numerical method has been validated through several simulation examples of practical microwave devices, including compact size band‐pass cavity filters and coupled dielectric resonators filters. The results have been compared to those provided by commercial full‐wave electromagnetic simulation software packages, showing in all cases a very good agreement, and with substantially enhanced numerical efficiencies. Key Points A novel and efficient integral equation formulation for the analysis of inductive steps including arbitrarily shaped conductor and dielectrics is presented Efficient Green's functions evaluation is shown