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A. Rennings

Finite Element Method (FEM) & Comsol Multiphysics

Part II: Electrodynamic Fields

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Outline

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Repetition: FEM for electrostatics

Today’s topics

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Vector wave equation - time-harmonic waves in 3D

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Weak form of the vector wave equation

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A simple approach that does not work –scalar basis functions for each component

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A better approach - vector (or edge) elements

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Node-based elements can still be usefulexample: in-plane TE waves

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Some common elementsused by default in Comsol Multiphysics

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Approximating a sine-wave with polynomials

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Degrees of freedom and memory demand

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Practical limitations - two trivial but fairly large examples

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Practical limitations - possible problems

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RF module overview: application modes in 3D

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RF module overview: important application modes in 2D

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Applicability of FEM/Comsol?

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Demo 1: Monopole antenna - setup

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Demo 1: Monopole antenna – important aspects

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Demo 1: Monopole antenna - results

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Demo 1: Monopole antenna - results

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Demo 2: Waveguide filter - setup

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later, we may simulate the same structure with FDTD /EMPIRE!

���� check the time for the simulations

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Demo 2: Waveguide filter – important aspects

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Demo 2: Waveguide filter - results

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next lecture…

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FDTD & EMPIRE: The Basics

next COMSOL-Tutorial on Tuesday 17.11.095 pm in BA328

“FEM simulations of electrodynamic fields”