EZ-tutorial-V20

Description

EMS+EZ-EMC & EZ-FDTD Tutorial –1IntroductionThe purpose of this tutorial is to help new users of EZ-EMC and EZ-FDTD learn to use this toolquickly. In each tutorial, a different modeling problem will be created, run, and the resultsdisplayed. Naturally, the users are encouraged to make their own models as desired. EZ-FDTDand EZ-EMC use the same Graphical User Interface to create models and display results. Allcomments and instructions in this tutorial will be shown as “EZ-EMC”, but apply to EZ-FDTD aswell. EZ-FDTD has many additional FDTD features for use in creating more complex models.Please refer to www.ems-plus.com for more details on the added features in EZ-FDTD.NOTE: This tutorial is NOT intended to teach FDTD or how to create models, etc. Please seethe references for other training and documentation for FDTD and/or modeling.Problem Example #1For this problem, the shielding performance of a metal plate with a single aperture will beevaluated.EZ-EMC StartYou can start EZ-EMC by selecting it from the programs menu (once EZ-EMC has beeninstalled.) Once the ‘nag’ screens are finished, select ‘Run EZ-EMC’, and the general menu willappear (Figure 1). To create a model, press ‘Define a Model’.Figure 1 General Menu1 1 Nov 2002EMS+Define a ModelOnce the ‘Define a Model’ button has been pressed, the Model Definition window will appear(Figure 2). Before a FDTD model can be created, a computational domain must be created (ALLmodel features ...

Informations

• Publié par: Nucheg
• Nombre de lectures: 17
• Langue: English

Extrait

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EZ-EMC & EZ-FDTD Tutorial –1

Introduction

The purpose of this tutorial is to help new users of EZ-EMC and EZ-FDTD learn to use this tool

quickly.

In each tutorial, a different modeling problem will be created, run, and the results

displayed.

Naturally, the users are encouraged to make their own models as desired.

EZ-FDTD

and EZ-EMC use the same Graphical User Interface to create models and display results.

All

comments and instructions in this tutorial will be shown as “EZ-EMC”, but apply to EZ-FDTD as

well. EZ-FDTD has many additional FDTD features for use in creating more complex models.

Please refer to www.ems-plus.com for more details on the added features in EZ-FDTD.

NOTE:

This tutorial is NOT intended to teach FDTD or how to create models, etc.

Please see

the references for other training

and documentation for FDTD and/or modeling.

Problem Example #1

For this problem, the shielding performance of a metal plate with a single aperture will be

evaluated.

EZ-EMC Start

You can start EZ-EMC by selecting it from the programs menu (once EZ-EMC has been

installed.)

Once the ‘nag’ screens are finished, select ‘Run EZ-EMC’, and the general menu will

appear (Figure 1).

To create a model, press ‘Define a Model’.

Figure 1

General Menu

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Define a Model

Once the ‘Define a Model’ button has been pressed, the Model Definition window will appear

(Figure 2).

Before a FDTD model can be created, a computational domain must be created (ALL

model features must exist within the computational domain).

The Computational Parameters tab

allows the user to select the FDTD cell size and the number of cells in each direction, for the

computational domain.

Figure 2 Computational Parameters

For this example, let’s set the FDTD cell size to 10 mm (0.01 meters) in the x, y, and z directions.

Let’s set the computational domain to be 50 cells in each direction.

Also, at this time, we’ll set

the number of time steps in the model to be 600.

Figure 3 shows the drawing space once the

‘Add’ button is pressed.

The box represents the computational domain.

Note that the view can

be zoomed, and rotated in Theta and Phi using the controls at the upper left side of the drawing

space, as shown in Figure 3a.

Note that once the ‘Add’ button was pressed, the other model definition tabs appeared behind the

computational parameters tab.

Select the ‘Plate’ tab.

We will create the plate halfway across the

computational domain in the x direction.

We will set the plate to start in the lower corner, and go

to the upper corner, completely cutting the domain into two domains.

(Note:

this is allowed with

the absorbing boundary condition used in EZ-EMC.

Bringing a plate directly against the ABC

simulates a plate to infinity in that direction.)

We’ll set the plate thickness to be 1 cell, and the

plate material to be Perfect Electrical Conductor (PEC).

PEC is a good approximation, since we

expect the metal plate to be greater than a few skin depths, and so all the energy from one side to

the other will be through the aperture.

Figure 4 shows the drawing with the plate.

The outline of

the plate is shown, allowing a view to any objects ‘behind’ the plate.

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Figure 3

Computational Domain

Figure 3a

Rotated/Zoomed Computational Domain

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Figure 4

Add Metal Plate

Next select the ‘Vent Hole’ tab.

We’ll select the aperture to be 10 cells by 2 cells and

horizontally directed.

We must select the x-direction start to be the same as the plate (25) and it’s

size to be the same as the plate (1).

We’ll set the aperture in the center of the plate, as shown in

Figure 5.

Next, we must put a source on one side, and a monitor point on the other side of the plate.

Let’s

place the monitor point first, by pressing the ‘Monitor point’ tab.

We simply use the cell

coordinates to define where the monitor point is positioned.

In this case, let’s put a monitor point

10 cells from the aperture and centered on the aperture.

Figure 6 shows the result once the

monitor point has been ‘added’.

For the source, we must first set the type of source by pressing ‘Source Parameters’.

Let’s use the

pseudo-wire and the derivative-of-Gaussian pulse.

(Note: when using a pseudo-wire source, you

must use the derivative-of-Gaussian pulse.)

The source amplitude is selected as 1000 for easy

normalization later (if desired).

The pulse width is set to 25 time steps.

The pulse width controls

the frequency domain content of the time domain pulse.

A wider pulse has more low frequency

content, and narrower pulse has more high frequency content.

Figure 7 shows this view.

At this

time, there is no change to the drawing area.

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Figure 5

Add Aperture to Metal Plate

Figure 6

Add Monitor Point

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Figure 7

Source Parameter

s

To finish specifying the source, we must specify the geometry by pressing ‘Source Geometry’.

We specify the source’s location using cells.

Let’s create a source that is vertically polarized to

optimize the emissions through the aperture.

So, we’ll select the source geometry as shown in

Figure 8.

Note the view has been rotated for easier viewing.

At this point, we could run the model.

But first, let’s set a movie plane so a animated movie will

be saved.

Select the ‘Movie’ tab.

As many movies as desired may be selected.

Figure 9 shows a

side-view of the model showing the movie plane cutting through the center of the model and

including the aperture.

The size of the resulting movie file can be quite large.

Since the fields do

not change rapidly with time, the temporal interval can be set to 5, without loss of viewing data,

and only 1-in-5 time steps will be saved..

The spatial interval is set to one, in this example, for a

fine resolution movie.

If the computational domain was much larger, the spatial interval could be

raised to save disk space.

The model must be saved to an input file.

Use the ‘File’ pull down menu to save the model as

example01.mdf.

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Figure 8

Source Geometry

Figure 9

Movie Plane

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Run a Model

At this point, it is time to run the model.

Select ‘Run a Model’ from the ‘Navigation’ pull down

menu.

Then select the file to run (example01.mdf) from the ‘File’ pull down menu, select ‘open

model and run’.

Figure 10 shows the running model window display during the model run.

Plot Simulation Results

Once the model has finished running (100% complete indication), then select the ‘Plot Simulation

Results’ option from the ‘Navigation’ pull down menu.

Select the ‘open file’ from the ‘File’ pull

down menu, and select the directory where the output files are located.

Note: EZ-EMC will

create an output directory called EZEMC_example01 (or EZFDTD_example01) under the

directory where the original input file is located.

All output files will be in this new directory.

On the left side of the screen, click on the + sign next to Monitor Points to expand the list of

monitor points.

Then click on the + sign next to MP_1 to see the list of field orientations

available.

Double click on Ez to view the time domain view of the z-directed electric field as

shown in Figure 11.

If frequency domain plots are desired, use the ‘Options’ pull down menu, select ‘Plot by ---

Frequency’.

The resulting plot is shown in Figure 12.

If additional monitor points are available, they can be selected by simply expanding the field list

for each desired monitor point, and double clicking on the desired field.

Likewise, other files

may be opened, and plotted on the same plot.

Figure 10

Run Model

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Figure 11

Plot Results in Time Domain

Figure 12

Plot Results in Frequency Domain

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View Animation

To see the animated movie of the fields, select ‘View Animation’ from the ‘Navigation’ pull

down menu.

Then select the file to view from the open file option in the ‘File’ pull down menu.

All movie files will be located in the output directory created by EZ-EMC.

Movie files will start

with the letters “MV”, then indicate the movie plane (e.g. XY), the location (e.g. 25), and the

field, (e.g. EZ)..

The movie can be single-stepped, or run repeatedly by using the buttons along

the left side of the drawing area.

Figure 13 shows an example of the movie display at a single

time step.

Summary

This tutorial is intended to get a new person started quickly, using EZ-EMC.

There are a number

of other options and features that are not discussed in this tutorial, but can be seen in the User’s

Manual.

Figure 13

Animation Display