Recent Enhancements in Simulation-Based Filter Design

Filter Designer 3D (FD3D) is an advanced synthesis tool to realize filters and diplexers. The user-friendly interface in addition to several template examples provide an easy understanding of the workflow with advanced design and visualization features that support Lowpass, Highpass, Bandpass, Bandstop and Diplexer designs. FD3D empowers the designer with access to various filter responses that can handle different transmission zeros adding more flexibility and the ability for group delay equalizer design. The tool supports several topologies in different guided-wave technologies including planar, cavities and lumped element filter implementation.

Filter model creation in FD3D is fast and robust thanks to the assembly procedure that allows user-defined building blocks in the component library followed by an automatic parameter mapping and simulation project set-up. All models created by FD3D are automatically optimized via a space mapping routine, based on the Eigen-mode results and the coupling matrix extraction. By default, the built-in Trust Region Framework optimizer with FD3D goal utilizes sensitivity results to greatly speed-up the optimization routine.

In this presentation, an overview of the FD3D tool is presented together with the latest features and added functionalities. Of particular interest is the newly introduced non-parametric optimization that enables engineers to create designs not limited by conventional and parametric shapes. In this regard, examples of how the combination of both tools can benefit the filter design are given.

Presenter: Majid NOROOZIARAB, Dassault Systèmes

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Optical properties of radially anisotropic cylinders

A radially anisotropic cylinder can be described by a permittivity tensor which is diagonal in cylindrical coordinates. Light scattering at such a structure can be tuned flexibly as the electric and magnetic resonances are adjustable independently from one another [1]. As of yet, such structures are studied solely theoretically and could not be fabricated. We focus on structures which can, in fact, be prepared of materials with rather low permittivity in the visible and near-infrared wavelength range. To realize anisotropic cylinders, we use a template: a dielectric membrane with cylindrical pores, such as nanoporous anodized aluminum oxide [2]. The pores can be filled with alternating dielectric layers or with a liquid crystal whose molecules arrange themselves in concentric rings inside the pores [3]. Theoretically, we are studying the far-field scattering patterns as well as the electromagnetic field inside the cylinder with light being incident orthogonally and obliquely to the cylindrical axis.

Presenter: Julia BRANDT, Hamburg University of Technology

Rough-surface lossy metal modelling in frequency range 110-170 GHz

Although there are several well-established models in electromagnetic simulation tools, the modeling of lossy metal material with rough surface is still a challenging task. In contrast to the traditional approach, where the metal is modeled based on estimation of conductivity and measurement of the surface mechanical properties, we propose the direct surface impedance extraction based on the S-parameters measurement of a suitable well-defined test sample. The entire procedure will be presented and discussed in terms of reliability and robustness. Finally, several practical hints will be provided in order to minimize a risk of failure during the reproduction of the extraction procedure in other labs.

Presenter: Vratislav SOKOL, Rohde & Schwarz závod Vimperk, s.r.o.

Investigating nanoporous gold structure for its unique optical properties

Nanoporous gold structure has gathered the attention and interest of scientific community due to its unique optical properties. To fully understand the nanoporous gold structure and its properties, full wave electromagnetic simulations are being carried out with different volume representations of nanoporous gold in CST Microwave Studio. The response of these simulated models is then compared with experimental spectra to comprehend its structural effects. Previously, cubic grid model provided npAu approximation qualitatively [1]. Now, our aim with simulations along with experimentally measured data is to provide complete and quantifiable insight into the complex geometry of nanoporous gold material and it will also help in developing an effective medium model which fits quantitatively as well.

Nanoporous gold is an irregular sponge-like structure formed with variable ligament or struts and pores in a nanometric regime. We are able to generate 3-D STL file of periodic structure through inverse fourier transform algorithm using MATLAB. Importing the STL file in CST Microwave Studio enables us to calculate optical response of nanoporous gold structure using frequency domain solver by employing unit cell boundary conditions. We calculate the average of resonances over different realizations as the position of resonances varies for each realization. Simulation results will reveal the behavior of structural and volume effects on overall response of the optical model. This talk will explain the utility of SIMULIA CST Studio Suite in evaluation and analysis of such complex geometrical structures.

Presenter: Muhammad Salman WAHIDI, Hamburg University of Technology

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