Training CST_2.pdf

CST MICROWAVE STUDIO®

Berezin Maksim

Ben-Gurion University.

Course “Antennas and Radiation”.

Advanced Ports

Ports for S-parameter computation

Discrete Ports

(lumped element)

Waveguide Ports

(2D eigenmode solver)

Input: Area for eigenmode solution

Output: E and H-Pattern,

Line Impedance,

Prop.constant (beta+alpha)

Input: Knowledge of TEM-Mode

Line Impedance

Output: Voltage and Current

Multipin ports

Open

Closed

Quasi-TEM

TEM

Wave Guide

Quasi-TEM

Inhomogeneous

Wave Guide

TEM

MultipinPort

Waveguide multipin ports

TEM Modes (H-field) from Eigenmode solver

User-selected TEM Modes

Advanced Meshing

Mesh Settings Overview

Time Domain (TD) ���� Hexahedral

Frequency Domain (FD)���� 1)Hexahedral

2)Tetrahedral

Hexahedral Mesh Properties

Lines per wavelength: This value is connected to the wavelength of the

highest frequency set for the simulation. It defines the minimum number of

mesh lines in each coordinate direction that are used for a distance equal

to this wavelength.

In a way, it sets the spatial sampling rate for the signals inside of your

structure.

Lower mesh limit: it defines a maximum distance between two mesh lines

for the mesh, by dividing the smallest face diagonal of the bounding box of

the calculation domain by this number.

Mesh line ratio limit: The calculation time is highly dependent on the

chosen mesh. Not only is the absolute number of mesh cells used

relevant, but also the distance between two mesh lines.

The smallest distance existing in a mesh directly influences the width of the

time steps usable in the simulation.

The smaller the smallest distance, the smaller the time step.

And the smaller the time step, the longer it takes to simulate a period of the

electromagnetic fields.

Smallest mesh step: Defines the absolute smallest mesh step used

Maximum step width of the mesh

Mesh Type

Automatic choice of mesh type:

FPBA for complex structures, imported models

otherwise: PBA

Control of mesh equilibration

Whenever the automatic mesh generation

finds it necessary to locate a mesh node

at a particular position it will mark this

with a fixpoint (red).

A density point (yellow) acts as a control point where the mesh

density may change. The automatic mesh generation uses these

points to refine the mesh within important regions.

Density and Fixpoints

Local Mesh PropertiesRight mouse-button

Max mesh step width = 1 Max mesh step width = 0.2

Priority: Mesher puts more emphasis

on objects with higher priority. Also,

materials with priority other than zero

will displace voxel data

Maximum mesh step width

Dx/Dy/Dz: For structure elements of

high importance for the simulation a

maximum step width for every

coordinate direction can be specified.

Extend x/y/z range by: Use this setting

to extend the maximum step width

outside the bounding box of this

structure element by the range given.

No Subgridding1987440 Meshcells

Meshing: 294 s + Solver: 14322 s

Total: 14616 s

Subgridding148922 Meshcells

Meshing: 607 s + Solver: 816 s

Total: 1423 s

Here: Subgridding reduces

• number of cells by factor > 13

• computing time by factor 10

Example: Spiral with phone and head

NO SUBGRID SUBGRID

Example: Spiral only

Mesh Settings Overview

Time Domain (TD) ���� Hexahedral

Frequency Domain (FD)���� 1)Hexahedral

2)Tetrahedral

Steps per wavelength: This value is connected to the

wavelength of the highest frequency set for the simulation. It

defines the minimum number of mesh cells that are used for a

distance equal to this wavelength.

Minimum number of steps: This value controls the global

relative mesh size and defines a lower bound for the number

of mesh cells independently of the wavelength. It specifies the

minimum number of mesh edges to be used for the diagonal

of the model bounding box. Consequently, the higher this

value, the finer the mesh.

General Settings

Important Parameter for TET Mesh generation

30

100

Tet-FD: Mesh Refinement

• Multi-frequency adaptive mesh refinement– sequentially processed adaptation frequencysamples before the broadband sweep

– example: diplexer

CST MWS SAR Modeling

Human Body + SAR-Examples

Head with

Mobile Phone

SAR with Spherical

Phantom Model

Influence of car and head

Arbitrary voxel

import

Visible Human Data Import + SAR-calculation

Data is

available

in several

resolutions.

EMI of Human Head

Meshing on head

Mesh View

Perfect Boundary Approximation enables the mesh to allow “mixed” cells in

non-uniform orthogonal mesh, having two different materials in same cell.

Head with Mobile Phone

Field for different Phone Positions

Phone in horizontal position

Phone in vertical position

CST 2008 Feature

Postprocessing Specials

Broadband Farfield monitors

Macros���� Farfield���� Broadband Farfield Monitors

Stationary current field

Thermal Solver in CST EM STUDIO™

Temperature distribution

Thermal losses caused by

electric currents can be used as

a driving source for a thermal

problem (LF and Stationary

currents)

Simulation coupled

with CST MWS