The Design of Cavity Resonators and Microwave Filters Applying Shape Deformation Techniques

Abstract

This paper introduces shape deformation as a new approach to the computer-aided design (CAD) of high-frequency components. We show that geometry deformation opens up new design possibilities and offers additional degrees of freedom in the 3D modeling of microwave structures. Such design flexibility is highly desirable if the full potential of Additive Manufacturing (AM) is to be exploited in the fabrication of RF & microwave devices. The use of deformation techniques in the design of high-frequency components allows the attainment of improved electrical parameters, such as high-quality factors for cavity resonators and wide higher-order mode separation. In this work, shape deformation with radial basis functions (RBFs) is integrated with an electromagnetic field simulator based on the 3D finite-element method (FEM), allowing the semiautomated optimization of microwave components, such as cavity resonators and filters. The proposed strategy is used for the design of high Q-factor cavity resonators and of cavity bandpass filters with improved spurious mode separation. Designs of third-order and sixth-order cavity filters with complex geometry are experimentally verified using 3D-printed prototypes with selective laser melting (SLM) technology.

A Circular Waveguide Dual-Mode Filter With Improved Out-of-Band Performance for Satellite Communication Systems

“…Based on the measured IL, the extracted Q of the filter is 2500, which corresponds to an effective conductivity of σ ef f = 1.72 • 10 6 S/m. This value is comparable to other reported aluminum structures fabricated with SLM [9], [15], [16]. This estimated conductivity σ ef f was taken into account in the EM simulations shown in this comparison.…”

“…The edges of the basic cylindrical cavity were filleted to form a smooth "pill" shape, which was then modified using shape deformation with radial basis functions [9]. The basic principle of this technique is to define a set of points around the object that will control the deforming operation.…”

State-of-the-Art: AI-Assisted Surrogate Modeling and Optimization for Microwave Filters

“…The automated generated circuits are intrinsically different from regular standard topology of microwave filters, which expand the design capability [85]. Another example is shape deformation technique for geometry optimization of microwave filter [113]- [114]. The method is performed based on computer graphics applications which is used for object manipulation.…”

A Circular Waveguide Dual-Mode Filter with Improved Out-of-Band Performance for Satellite Communication Systems

“…Then, various cavity shape modifications were investigated to achieve an improvement in the spurious-free region over the state-of-the-art stepped CWDM cavity [8], while maintaining a similar unloaded Q. The edges of the basic cylindrical cavity were filleted to form a smooth "pill" shape, which was then modified using shape deformation with radial basis functions [9]. The basic principle of this technique is to define a set of points around the object that will control the deforming operation.…”