Abstract
This paper presents a novel full-wave technique which allows for a fast 3D finite element analysis of waveguide structures containing rotatable tuning elements of arbitrary shapes. Rotation of these elements changes the resonant frequencies of the structure, which can be used in the tuning process to obtain the S-characteristics desired for the device. For fast commutations of the response as the tuning elements are rotated, the 3D finite element method is supported by multilevel model-order reduction, orthogonal projection at the boundaries of macromodels and the operation called macromodels cloning. All the time-consuming steps are performed only once in the preparatory stage. In the tuning stage, only small parts of the domain are updated, by means of a special meshing technique. In effect, the tuning process is performed extremely rapidly. The results of the numerical experiments confirm the efficiency and validity of the proposed method.
Highlights
Waveguide structures loaded with discontinuities, such as posts and irises, play an important role in wireless communication systems
In [3] an efficient method based on the orthogonal expansion method and an iterative scattering procedure has been proposed for analyzing waveguide filters with rotatable posts of shapes that conform to cylindrical coordinates
In order to allow for rotation and at the same time to perform the orthogonal projection technique of [7], [10] we developed a new set of basis functions that is applicable to cylinders
Summary
Waveguide structures loaded with discontinuities, such as posts and irises, play an important role in wireless communication systems. We propose a novel efficient 3D method based on FEM that, unlike [3] and [4], allows for arbitrary shapes of rotatable elements in fast tuning and optimization It combines the meshing techniques from [5] with the model order reduction (MOR), which has been demonstrated previously for FDFD [6], [7], 2D FEM [8], [9] and 3D FEM [10], [11]. The mathematical formulation of this approach is similar to that presented in [10], the main difference being a new technique of incorporating the macromodels within a fixed mesh, that allows for a single macromodel to be either rotated or simultaneously rotated and replicated without the need to regenerate the mesh This substantially speeds up the computation and makes a fast design tuning possible.
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