Space mapping optimization of waveguide filters using finite element and mode-matching electromagnetic simulators

Abstract

For the first time in design optimization of microwave circuits, the aggressive space mapping (SM) optimization technique is applied to automatically align electromagnetic (EM) models based on hybrid mode-matching/network theory simulations with models based on finite-element (FEM) simulations. SM optimization of an H-plane resonator filter with rounded corners illustrates the advantages as well as the challenges of the approach. The parameter extraction phase of SM is given special attention. The impact of selecting responses and error functions on the convergence and uniqueness of parameter extraction is discussed. A statistical approach to parameter extraction involving 𝓁1 and penalty concepts facilitates a key requirement by SM for uniqueness and consistency. A multipoint parameter extraction approach to sharpening the solution uniqueness and improving the SM convergence is also introduced. Once the mapping is established, the effects of manufacturing tolerances are rapidly estimated with the FEM accuracy. SM has also been successfully applied to optimize waveguide transformers using two hybrid mode-matching/network theory models: a coarse model using very few modes and a fine model using many modes to represent discontinuities. ©1999 John Wiley & Sons, Inc. Int J RF and Microwave CAE 9: 54–70, 1999.