Topics: Ansoft HFSS — Material Manager Material...

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terials from the global

. You can define new

pears:

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Ansoft HFSS — Material Managerics:

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Material ManagerSelect Setup Materials to do the following:

• Specify the material attributes for objects by assigning madatabase to them.

• Create new materials and add them to the local databasematerials, or derive them from existing materials.

When you choose Setup Materials, the following window ap

erial Managerifying the Material Setuperal Procedureerial Databaseing Materials to the Data-seigning Materials to jectsing Inside or on the Sur-eluded Objectsnging Material Attributes

eting Materialserial Attributescting Several Objects at ceelecting Objectsfectly Matched Layersparing Thick- and Thin- Resistivity Values

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ell Online Help System 199 Copyright © 1996-2002 Ansoft Corporation

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following message appears:

ments and save those and will have to be s are to be saved, ncel” to cancel this

w-only mode. You can view,

nts. If you modify and save t solve the problem again.

xecutive Commands

n you assign a material to as relative permeability, rel- the object.

terial to all “unassigned” 3D

dd all the materials you

desired, specify whether ct.

ect substrate, first add rial polyamide to the object

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Modifying the Material SetupIf you select Setup Materials after generating a solution, the

If you make changes to the material assignchanges, all solution data will be deletedrecomputed. Pick “View Only” if no change“Modify” if changes are to be saved or “Caoperation.

> Do one of the following:• Choose View Only to access the Material Manager in vie

but not change all material properties and assignments.• Choose Modify to change the existing material assignme

any material assignments or material definitions, you musAll solution data are deleted.

• Choose Cancel to abort the command and return to the Ewindow.

General ProcedureAll 3D objects in the model must be assigned a material. Whean object, the properties associated with the material — suchative permittivity, conductivity, and so forth — are assigned to

To set up a valid model in Ansoft HFSS, you must assign a maobjects in the model.

> Assigning materials is a two-step process:1. If they are not already included in the material database, a

will need.2. Assign a database material to each object in the model. If

to generate a solution inside or on the surface of the obje

For example, to assign polyamide as the material for the objpolyamide to the material database and then assign the matesubstrate.

erial Managerifying the Material

tuperal Procedure

erial Databaseing Materials to the Data-seigning Materials to jectsing Inside or on the Sur-eluded Objectsnging Material Attributes


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rials that may be assigned

e used throughout all Max-deleted or modified from the are listed as External screen.

ced by the local project from can add new materials to a can be deleted or modified e accessed by other

. Any Local or External objects in its model.

e database, allowing you to acteristics of the base mate-aterials as necessary.

he common characteristics f the base material. In addi-inate redundancies in

e a material to remove any

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Material DatabaseThe material database consists of a group of predefined mateto individual objects in a model.

Global Material DatabaseThe global material database is the primary material databaswell software. Materials from the global database can only be Maxwell Control Panel, not from the Material Manager. Thesematerials in the materials list displayed in the lower left of the

Local Material DatabaseThe local material database is a copy of any materials referenthe global material database supplied with Ansoft HFSS. Youproject’s local database. Materials added to a local databasewithout affecting the global database. However, they cannot bprojects and are flagged as Local materials in the display listmaterial in a project’s material database may be assigned to

InheritanceNew materials can be “derived” from any existing material in thcreate a family of materials that share, or inherit, several charrial. You can then modify the characteristics of the derived m

One advantage to deriving materials is that you can change tof all materials in the family by changing the characteristics otion, it makes accessing material data faster and helps to elimrelated materials. If you want to prevent this, you can underivassociations it has to the original material.

erial Managerifying the Material Setuperal Procedureerial Databaselobal Material atabase

ocal Material Databaseheritanceing Materials to the Data-seigning Materials to jectsing Inside or on the Sur-eluded Objectsnging Material Attributes


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l database, add them as

dding Frequency- dent material.

e parent material.

nder Material s the default name of

fields.utomatically set to infinity. of the material’s anisotropy

described under B-H ble for Driven Solution

ency-Dependent Materials.ter. assigned to objects.

y with direction. s of a ferrite. Nonlinear

igenmode Solution problems.

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Adding Materials to the Database> If the materials you want to use are not in the project’s materia

follows:1. Do one of the following:

• To create a new material, choose Material/Add. See ADependent Materials to create a new frequency-depen

• To derive a material from an existing material:a. Select a material in the Material list box. This is thb. Choose Material/Derive.

2. Optionally, enter a new name for the material in the field uProperties. The stem word Material is reserved for use anew materials.

3. If appropriate, select one of the following material types:

4. Enter the material’s properties in the Material Attributes • For perfect conductors, the material’s conductivity is a• For anisotropic materials, specify the major diagonals

tensors.• For ferrite materials, specify the material properties as

Nonlinear Material. Nonlinear materials are only availaproblems.

• For frequency-dependent materials, see Adding Frequ5. After all material characteristics have been set, choose EnThe new material now appears in the Material list and can be

Perfect Conductor A perfectly conducting material.Anisotropic Material A material whose properties varB-H Nonlinear Material A material with the characteristic

materials are not available for E

erial Managerifying the Material Setuperal Procedureerial Databaseing Materials to the tabasedding Frequency-ependent Materials

igning Materials to jectsing Inside or on the Sur-eluded Objectsnging Material Attributes


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he field excitation. This fre- range and constant outside

frequency range 20 - 50

frequency range

perty is constant.operty is constant.

se the Material Input win-bove the frequency range.

linear dataset that specifies n generation. This dataset

solved using a discrete or

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Adding Frequency-Dependent MaterialsThe properties of some materials vary with the frequency of tquency dependence is often linear within a certain frequencyof the frequency range, as shown below,

where

• epsrlower is the relative permittivity of a material below theGHz.

• epsrupper is the relative permittivity of a material above the20 - 50 GHz.

• flower is the lower frequency, below which the material pro• fupper is the upper frequency, above which the material pr

To account for the variance within a given frequency range, udow to specify a property’s values at frequencies below and aBased on these values, Ansoft HFSS automatically creates athe property’s values at the desired frequencies during solutiocan be modified with additional points if desired.

Frequency-dependent materials are appropriate for problemsinterpolating sweep.

epsrlower

epsrupper

fupperflower


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Topone or more frequency-

put window appears:

aterial’s property values

material’s property

the lower frequency you

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> To add a material to the project’s material database that has dependent material properties:1. Choose Help/Input FreqDeptMat/Input. The Material In

2. Enter a lower frequency. Ansoft HFSS assumes that the mremain constant below this frequency.

3. Enter an upper frequency. Ansoft HFSS assumes that thevalues remain constant above this frequency.

4. Enter the permittivity of the material at frequencies below entered in step 2.





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Topthe upper frequency you t vary with frequency, er frequency.bility, and magnetic loss

terial property. Based on the property’s values at

ty fields in the Material

list and can be assigned

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5. Enter the permittivity of the material at frequencies above entered in step 3. If the permittivity of the material does noenter the same value you entered for the permittivity’s low

6. Follow steps 4 and 5 for the electric loss tangent, permeatangent fields.

7. Choose OK.

Ansoft HFSS automatically creates a dataset for each maa varying property’s dataset, the software can interpolate the desired frequencies during solution generation.

New default function names appear in the material properManager window.

8. Choose Enter. The new material appears in the Material to any object.

See also, Editing Frequency-Dependent Materials.


igning Materials to jectsing Inside or on the Sur-eluded Objectsnging Material Attributes


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se, you can assign them to

of the following:isplayed on the left side of

its name are both selected.electing Several Objects at

characteristics are the Material Manager

, choose Assign.bject, the window on the ntation. The default bject’s coordinate

on of Ansoft HFSS is dif-iations in Screen Dis-

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Assigning Materials to ObjectsAfter any materials are added to the project’s material databaobjects.

> To assign materials to objects:1. Select the objects to be assigned a material by doing one

• Select the name of an object from the Object list box dthe screen.

• Select an object in the display window. The object and• To select multiple objects, follow the procedure under S

Once.

2. Select the name of the material to assign to the object. Itsdisplayed in the Material Attributes box at the bottom of window.

3. With both the object name(s) and material name selected4. If a material with anisotropic properties is assigned to an o

following page appears. Specify the tensor or function orieorientation for the material aligns it with the x-axis of the o

Note: The procedure for selecting objects on the PC versiferent from that of the Workstation version. See Varplays and Commands for details.

erial Managerifying the Material Setuperal Procedureerial Databaseing Materials to the Data-eigning Materials to jectsaterial Orientationing Inside or on the Sur-eluded Objectsnging Material Attributesting Materials



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t in the model. Ansoft HFSS bjects have been assigned

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system.

Repeat this procedure to assign a material to every 3D objecwill not allow you to continue setting up your model until all omaterials.

erial Managerifying the Material Setuperal Procedureerial Databaseing Materials to the Data-seigning Materials to jectsaterial Orientationing Inside or on the Sur-eluded Objectsnging Material Attributes


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g to the position inside an uld vary if there is a density irection according to the

efined as functions.

ne a material property

object, the menu prompts oordinate system.

object, is used to evaluate ing to their position. By l xyz-coordinate system and

ppears.

action.

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Material OrientationThe properties of some materials vary in magnitude accordinobject. For instance, conductivity and relative permeability cogradient across the object. Other material properties vary in dposition inside an object. Such material properties must be d

In addition, functional material properties can be used to defiaccording to a mathematical expression.

When you assign a material with anisotropic properties to anyou to specify the material’s orientation to the object’s local c

The object coordinate system, which is associated with eachmaterial properties that vary in magnitude or direction accorddefault, the object coordinate system is aligned with the globahas its origin at the center of the object.

> To specify the direction of an anisotropic material:1. Choose Assign. The Assignment Coord. Sys. window a2. Assign the material to the object. 3. Select one of the following options:

• Align with object’s orientation • Align relative to object’s orientation • Align with a given direction

4. Choose OK to assign the material or Cancel to cancel the



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ordinate system.

ion.

l in the About X, About

s. s. This rotates the x-axis A positive angle moves the angle moves the x-axis in

s. This rotates the x-axis

ntation out of either

sor is rotated α degrees degrees about the y-

t the z-axis.

e values.

z

y

x

About Z

y’

x’

γ

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Align with Object’s OrientationThis aligns the material with the x-axis of the object’s local co

> If you selected with object’s orientation: • Choose OK to accept the alignment.

The About X, About Y, and About Z fields remain inactive.

Align Relative to Object’s OrientationThis option aligns the material relative to the object’s orientat

> If you selected relative to object’s orientation (the default):1. Enter the Relative Orientation (in degrees) of the materia

Y, and About Z fields: • About X — the rotation of the material about the x-axi• About Y — the rotation of the material about the y-axi

(and thus the object’s orientation) within the xz-plane. x-axis in the negative z direction. Likewise, a negativethe positive z direction.

• About Z — the rotation of the material about the z-axi(and thus the object’s orientation) within the xy-plane.

Combining About Y and About Z rotates the object’s orieplane.This concept is illustrated below. In the first panel, the tenabout the x-axis. In the second panel, a tensor is rotated βaxis. In the third panel, a tensor is rotated γ degrees abou

2. Choose OK to accept these values or Cancel to ignore th

y

y’

α

z’

x x

z

y

About X About Yz

β

z’ x’



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m. This lets you specify the efine a functional material .

the function in the low each field to specify nctions, you may then

and re-enter the values.nter the coordinates of lds..

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Align with a Given DirectionAligns the material at an angle to the global coordinate systedirection in which an anisotropic material property points, or dproperty that acts at an angle to the global coordinate system

> If you selected with a given direction:1. Enter the About X, About Y, and About Z (in degrees) of

Global Orientation fields. You must select the buttons bewhich values are functions. If you specify any values as fuenter the origin in the Global Origin field.

2. If necessary, choose Reset to reset the values of the field3. If a material with functional properties is being assigned, e

the new global origin for the function in the X, Y, and Z fie4. Choose OK to accept the values or Cancel to cancel them



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y whether to generate a field elect to generate a solution bject and generate a solu-

surface of the object, Ansoft

Inside is set to Yes. Con-ace of an object, Solve

ects with a conductivity less

bject:

solution inside the object. a solution only on the

. The background is r the fields in a perfect con-

et to No. Perfect insula-

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Solving Inside or on the SurfaceWhen you assign a material to an object, you may also specifsolution inside an object or on the surface of an object. If youinside the object, Ansoft HFSS will create a mesh inside the otion from the mesh. If you elect to generate a solution on the HFSS will only create a surface mesh for the object.

If a solution is going to be generated inside an object, Solve versely, if a solution is only going to be generated on the surfInside is set to No.

By default, Solve Inside is automatically set to Yes for all objthan 105 siemens/meter.

> To change whether or not a solution is generated inside an o1. Select the object you wish to change.2. Do one of the following:

• Choose Solve Inside to have Ansoft HFSS generate a• Choose Solve Surface to have Ansoft HFSS generate

surface of the object.

Excluded ObjectsThe background object is always excluded from the problemdefined as a perfect conductor; Ansoft HFSS will not solve foductor, making it theoretically non-existent.

Note: Perfect conductors will always have Solve Inside stors will always have Solve Inside set to Yes.

erial Managerifying the Material Setuperal Procedureerial Databaseing Materials to the Data-seigning Materials to jectsving Inside or on the rfaceluded Objectsnging Material Attributes

eting Materialscting Several Objects at ceelecting Objectsfectly Matched Layersparing Thick- and Thin- Resistivity Values

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ject’s local material

st. The attributes of the

for instructions on changing

or instructions on how to

requency-Dependent

the material’s original

cted material.

global database. These rial list.

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Changing Material Attributes> To change the attributes associated with a material in the pro

database:1. Select the appropriate Local material from the Material li

selected material appear in the Material Attributes box.

2. Optionally, change the type of material.3. Modify the appropriate material characteristics.

• If the material is anisotropic, see Anisotropic Materialsthe material’s attributes.

• If the material is a ferrite, see B-H Nonlinear Material fmodify its attributes.

• If the material has functional properties, see Editing FMaterials for instructions on how to modify functions.

4. Choose Revert to delete the changes and revert back to properties.

5. Choose Enter to save the new characteristics for the sele

Note: You cannot modify the properties of materials in thematerials are labeled as External (lock) in the Mate

erial Managerifying the Material Setuperal Procedureerial Databaseing Materials to the Data-seigning Materials to jectsing Inside or on the Sur-eluded Objectsnging Material

tributesditing Frequency-ependent Materials

nderiving a Materialeting Materialserial Attributescting Several Objects at ceelecting Objectsfectly Matched Layersparing Thick- and Thin- Resistivity Values

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put window appears.atically generated by Ansoft finitions window appears. re information on modifying

terials.

de to the original material rties of the base material. To ciations it has to the original

l list.erivative of the original riginal. Making changes material.

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Editing Frequency-Dependent Materials> To edit a frequency-dependent material:

1. Select the material to edit from the Material list.2. Choose Help/Input FreqDeptMat/Input. The Material In

• Alternatively, you can modify a dataset that was automHFSS. To do so, choose Functions. The Function DeSee the Dataset Editor section of the online help for modatasets.

3. Follow the procedure for adding frequency-dependent maUnderiving a Material

If a material has been derived from another, any changes maalso changes all its derivatives unless you override the propeprevent this, you can underive a material to remove any assomaterial.

> To underive a material:1. Select the material you wish to underive from the Materia2. Choose Material/Underive. The material is no longer a d

material but retains all the material characteristics of the oto the original material will no longer affect the underived

erial Managerifying the Material Setuperal Procedureerial Databaseing Materials to the Data-seigning Materials to jectsing Inside or on the Sur-eluded Objectsnging Material

tributesditing Frequency-ependent Materials

nderiving a Materialeting Materialserial Attributescting Several Objects at ceelecting Objectsfectly Matched Layersparing Thick- and Thin- Resistivity Values

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re marked as

from it will be listed as r, retain the characteristics

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Deleting Materials> To delete a material from the local material database:

1. Select the Local material you wish to delete.2. Choose Material. A menu appears.3. Choose Clear.The material is deleted. Any objects assigned that material aUNASSIGNED.

Deleting Derived MaterialsIf you delete a material, any materials that have been derivedUnderived in the Material Attributes box. They will, howeveof the deleted material.

erial Managerifying the Material Setuperal Procedureerial Databaseing Materials to the Data-seigning Materials to jectsing Inside or on the Sur-eluded Objectsnging Material Attributeseting Materialseleting Derivedaterials

erial Attributescting Several Objects at ceelecting Objectsfectly Matched Layersparing Thick- and Thin- Resistivity Values

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rties of a linear, isotropic ency-Dependent Material

terial, εr, in the Rel. Permit-

l. Permeability (Mu).

ld.

equency electric field, enter ic Loss Tangent field. The

ay vary with frequency. To tangent.

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Material AttributesUse the following fields to describe the electromagnetic propematerial. To represent frequency dependency, see the FrequProperty Functions section of the online help.

Relative PermittivityEnter the relative permittivity (the dielectric constant) of a mativity(Eps) field.

The relative permittivity is a dimensionless number.

Relative PermeabilityEnter the relative permeability of a material, µr, in the field ReThe relative permeability is a dimensionless number.

ConductivityEnter the conductivity of a material, σ, in the Conductivity fie

Conductivity is entered in siemens/meter.

Electric Loss TangentTo represent a dielectric that dissipates the power of a high-frthe dielectric loss tangent, ε′′/ε′, for the material in the Electrsmaller the loss tangent, the less lossy the material.

The actual dielectric loss tangent associated with a material msimulate the variances, define a function for the electric loss



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equency magnetic field, Magnetic Loss Tangent l.

t includes dielectrics, t does not vary signifi-o, the results may not be vary significantly over py and solve the project ated frequency range for ly stable over the

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Magnetic Loss TangentTo represent a dielectric that dissipates the power of a high-frenter the magnetic loss tangent, µ′′/µ′, for the material in the field. The smaller the loss tangent, the less lossy the materia

Note: If you plan to do a frequency sweep for a project thamake sure that the electric or magnetic loss tangencantly over the requested frequency range. If they dwhat you expect. In cases where loss tangent doesthe frequency range in which you are interested, coseveral times, adjusting the loss tangent and associthe copied project so that the loss tangent is relativeproject’s requested frequency range.

erial Managerifying the Material Setuperal Procedureerial Databaseing Materials to the Data-e




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t several objects at once

h object or object name.king the mouse button on

st letter or some other ld appears:

sion that identifies the ts that begin with the

jects are selected, assign a

lick on the object or group’s

lect. The objects are

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Selecting Several Objects at OnceIf more than one object is made of a particular material, selecusing one of the following methods:

> Use the mouse to select several objects as follows:1. Choose Multi. Select.2. Do one of the following:

• For UNIX machines, click the left mouse button on eac• For PC’s, hold down the Shift or Ctrl keys to while clic

each object or object name.> Use the Select commands as follows:

• Choose By Name to select objects that have the same fircharacteristic of their names in common. The following fie

Enter object name/regular expressionUsing asterisks as a wildcard characters, enter an expresobjects you wish to select. For example, to select all objecletter c, enter c*.

• Choose All Objects to select all objects.

The names of all selected objects are highlighted. After the obmaterial to the selected objects.

Deselecting Objects> To deselect selected objects:

• To deselect a single selected object or group of objects, cname in the list.

• To deselect all selected objects and groups, choose Desedeselected and their names are no longer highlighted.



erial Attributescting Several Objects nce

electing Objectsectly Matched Layersparing Thick- and Thin- Resistivity Valuesaces


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material that fully absorbs ial requires that you define tropic.

Ansoft HFSS is to embed this box is assigned a radia-adiation boundary condition

iator inside an air box. How-x, add several layers of spe- are biaxial anisotropic with n below:

PML

PML

PML

xyz

xy

x

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Perfectly Matched LayersPerfectly matched layers (PMLs) are created from a fictitiousthe electromagnetic field impinging on it. This fictitious materboth the permittivity and the permeability to be complex aniso

Embedded PMLsThe traditional procedure for analyzing a radiating structure inthe radiator within an air-filled box. The outermost surface of tion boundary condition, which utilizes a second-order local r(ABC).

Follow a similar procedure to use PMLs; that is, place the radever, instead of placing a single ABC on the outside of the bocialized materials to absorb the outgoing waves. These PMLsspecial complex material characteristics. An example is show

PML

PML

z

y



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Topterface, the biaxial diagonal and PMLz) are:

ML layer corresponding to ated tensors for y- and

ct a box with PML walls. To o PML objects meet, create

e object joining PMLx and

irected and y- and z-

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To ensure that there will not be any reflection at the PML/air inmaterial tensors for x-, y- and z-directed PMLs (PMLx, PMLy,

For PMLx:

For PMLy:

For PMLz:

where C = a - jb.

The tensors designated as PMLx characterize an x-directed Pa PML wall in the yz plane. Similarly, PMLy and PMLz designz-directed PML layers.

PMLs of different directions must be joined in order to construensure complete coverage where the edges and corners of twspecial edge and corner PML objects. The tensors of an edgPMLy are:

For PMLxy:

A similar tensor construction rule is valid for joining x- and z-ddirected PMLs. The tensor for a corner object is:

ε[ ]ε0------- 1

C---- C C= µ[ ]

µ0-------- 1

C---- C C=

ε[ ]ε0------- C 1

C---- C= µ[ ]

µ0-------- C 1

C---- C=

ε[ ]ε0------- C C 1

C----= µ[ ]

µ0-------- C C 1

C----=

ε[ ]ε0------- 1 1 C2= µ[ ]

µ0-------- 1 1 C2=





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boundary conditions on the x either with perfect electric general, use PECs because

ire any special procedure in ns can be used for any PML Ls depends on the material

netic field decays strongly in kept below a prescribed be satisfied:

quencies.

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For PMLxyz:

The next step of embedding a problem in PMLs is to specify outer surface of the box. The simplest way is to bound the boconductors (PEC) or perfect magnetic conductors (PMC). In they reduce the problem size.

Setting PML ParametersTo enter the matrices of the anisotropic materials doesn’t requthe Material Manager. The usual anisotropic material definitiostructure. However, keep in mind that the efficiency of the PMvalues assigned to them.

Setting the complex parameter C ensures that the electromagthe PMLs. Back reflections from the bounding PECs are thenbound. To accomplish this, the following inequalities have to

where

• e = a = b• a and b are the real and imaginary parts of C.• H is the thickness of the PML object.• ωmax and ωmin are the minimum and maximum angular fre

ε[ ]ε0------- C C C= µ[ ]

µ0-------- C C C=

e ρln–2DminH------------------- emin=≥

e dln–2Dmaxh------------------- emax=≤

Dmin αmin βmin+ 1rmax----------

ωminc-----------+= =

Dmax αmax βmax+ 1rmin---------

ωmaxc

------------+= =





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approximately 3.1-3.)

nd:

PML. This means that the bjects and provides ted differently when incident

creation process. They .

objects.

ces of the box to turn into

prompt. From here you

a box using the location int. You can specify the to specify the origin as

pting you for the size of e layers, you will select

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• rmax and rmin are the minimum and maximum distance of asurface.

• ρ is the bound for back reflection.• d is the maximum decay characterizing the element. (d is • h is the thickness of one finite element.• c is the velocity of light in vacuum.

Things to ConsiderWhen you are creating PMLs, keep the following things in mi

• The names of PML objects should begin with PML.• Each object whose name begins with PML is treated as a

software performs additional mesh refinement for those oinformation for post processing. PML objects are also treawaves are present.

PML MacrosAnsoft HFSS includes several macros that automate the PMLdraw layers similar to these and assign the material matrices

3D Modeler PML MacrosUse the PMLCoverSetup macro to automatically create PML

PMLCoverSetup allows you to draw a box, then select the falayers. These layers represent the PMLs.

> To draw the PML objects:1. Choose View/Command Prompt to display the command

can start the PMLCoverSetup macro. 2. Enter PMLCoverSetup in the command line. This creates

of the cursor in the selected view window as a starting postarting point when you start the command. For example,the starting point, enter the following:

PMLCoverSetup [0,0,0]3. Choose Enter to start the macro. A window appears, prom

the base box and the thickness of the layers. To create th





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ers in the X Size, Y Size,

the base box with PMLs. oose OK, and you need

prompting you to select

cting the faces.select adjacent faces, ogether.There are two Enter in the command prompt.

used to create the layers.

etup macro or manually), es you with a macro that s PML materials to objects

pting you to enter

e following:

names all start with PML em as PMLs. Do not convention is shown in

PMLCoverSetup macro.nually.

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the faces of the box. Each selected face will become a PM4. Enter the size of the base box and the thickness of the lay

Z Size, and Layer Thickness fields.5. Select Cover all faces with PML to cover all the faces of

If you select this, the PML objects are created after you chnot select the faces of the base box to cover with PMLs.

6. Choose OK to create the base box. A message appears, the faces of the box from which to create layers.

7. Choose OK to acknowledge the message and begin sele8. Select the faces of the base box to turn into layers. If you

edge and corner objects will be created to join the faces t9. Choose Enter when you are finished selecting the faces.

buttons you can choose, one in the side window, and one You may choose either.

The faces you selected are detached from the base box and

Material Manager PML MacrosAfter you have drawn the PML objects (with the PMLCoverSyou must assign PML materials to them. Ansoft HFSS providautomates this process. PMLMatSetup automatically assignwhose name begins with PML.

> To assign materials to PML objects:1. Press CTRL - F4 to display the command prompt.2. Enter PMLMatSetup in the command prompt.3. Choose Enter to start the macro. A window appears, prom

information about the nature of the PML objects.4. Specify how the macro was created by selecting one of th

Warning: Names are automatically given to the layers. These and are necessary for Ansoft HFSS to recognize thchange the names of the PML objects. The namingthis figure.

PML macro PML objects were drawn withUser drawn objects PML objects were drawn ma





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f the following:

e window that appears low that corresponds to

L objects is air or vacuum.L objects is a material other

space.ansmission line.

ion are not valid setups.

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5. Specify the type of material of the object in contact with thobject is the base box if you used PMLCoverSetup. Sele

6. Specify how the PML objects terminate by selecting one o

7. Choose OK to proceed with the settings you selected. Thdepends on the settings you selected. Select the setup beyour settings for instructions on how to proceed:• PML/Air/Free • PML/Other/Free • User/Air/Free • User/Air/Guided • User/Other/Free • User/Other/Guided

Air/vacuum Object in contact with the PMOther materials Object in contact with the PM

than air or vacuum.

Free radiation PML objects terminate in freeGuided waves PML objects terminate in a tr

Note: PML/Air/Transmission and PML/Other/Transmiss





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field. This is the lowest

y field. This is the lve for.

to the full range of . By indicating a broad bsequent solutions. ent and longer solution

erials based on the settings se names begin with PML.




he PML objects in the

the PML objects in the

erials based on the settings se names begin with PML.

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PML/Air/Free> To specify the settings for a PML/Air/Free setup:

1. Enter the minimum frequency in the Minimum frequencyfrequency of the frequency range you intend to solve for.

2. Enter the maximum frequency in the Maximum frequenchighest frequency of the frequency range you intend to so

The frequency range you specify here should correspondfrequencies you intend to use in any subsequent solutionfrequency range, you increase your flexibility in running suHowever, a large range will result in greater mesh refinemtimes.

3. Choose OK to proceed with the settings you selected.

The software automatically creates the appropriate PML matyou specified and assigns these materials to the objects who

PML/Other/Free> To specify the settings for a PML/Other/Free setup:




3. Enter the relative permittivity of the base object touching tRel. Permittivity field.

4. Enter the relative permeability of the base object touchingRel. Permeability field.


The software automatically creates the appropriate PML matyou specified and assigns these materials to the objects who





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als. To properly assign a cts can all be treated rdinate system


y field. This is the


d the radiating bodies in quired because the PML f their near fields at the inimum distance

. If you have multiple losest and use that

hickness field. The ave the specified ML macro for each

etermined by the

erials based on the settings

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User/Air/Free> To specify the settings for a User/Air/Free setup:

1. Select the PML objects to which to assign the PML materiPML material to objects, you must ensure that these objeuniformly, with regard to the PML thickness and local cooorientation.

2. Enter the minimum frequency in the Minimum frequencyfrequency of the frequency range you are solving.

3. Enter the maximum frequency in the Maximum frequenchighest frequency of the frequency range you are solving.


4. Enter the minimum distance between the PML objects anthe Minimum radiating distance field. This distance is rematerial characteristics depend on the cumulative effect olocation of the PML object surfaces. This distance is the mbetween any of the radiating bodies and the PML objectsradiating bodies and multiple PML objects, take the two cdistance.

5. Enter the thickness of the PML objects in the PML layer tmacro only assigns a PML material to those objects that hthickness. If your PML objects vary in thickness, run the Pthickness.

6. Select the orientation of the PML objects. Orientation is ddirection of outward propagation.


The software automatically creates the appropriate PML mat





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order to properly assign ll be treated uniformly, tem orientation. in the Propagation

y in the Propagation


etermined by the


ickness and local orien-tion of your PML objects

atSetup macro will not must run the macro for or orientation from the

pagation constants for he range you specify ies you intend to use in

uency range, you ions. However, a large ger solution times.

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you specified and assigns these materials to the selected obj

User/Air/Guided> To specify the settings for a User/Air/Guided setup:

1. Select the PML objects to assign the PML materials to. Ina PML material, you must ensure that these objects can awith regard to the PML thickness and local coordinate sys

2. Enter the propagation constant at the minimum frequencyconstant at min. frequency field.

3. Enter the propagation constant at the maximum frequencconstant at max. frequency field.





Note: The material property calculations depend on the thtation of the PML objects. If the thickness or orientavaries, the material assignments made by the PMLMbe valid if done for all PML objects at one time. Youeach group of PML objects that varies in thickness others.

Note: The frequency range corresponds to a range of prothe waveguides or transmission lines to terminate. There should correspond to the full range of frequencany subsequent solution. By indicating a broad freqincrease your flexibility in running subsequent solutrange will result in greater mesh refinement and lon





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order to properly assign jects can all be treated rdinate system



d the radiating bodies in quired because the PML f their near fields at the inimum distance

. If you have multiple losest and use that

he PML objects in the



pond to the full range of lution. By indicating a in running subsequent ter mesh refinement and

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User/Other/Free> To specify the settings for a User/Other/Free setup:

1. Select the PML objects to assign the PML materials to. Ina PML material to objects, you must ensure that these obuniformly, with regard to the PML thickness and local cooorientation.



4. Enter the minimum distance between the PML objects anthe Minimum radiating distance field. This distance is rematerial characteristics depend on the cumulative effect olocation of the PML object surfaces. This distance is the mbetween any of the radiating bodies and the PML objectsradiating bodies and multiple PML objects, take the two cdistance.



Note: The frequency range you specify here should corresfrequencies you intend to use in any subsequent sobroad frequency range, you increase your flexibilitysolutions. However, a large range will result in grealonger solution times.


eting Materialserial Attributescting Several Objects at ceelecting Objectsfectly Matched Layersmbedded PMLsetting PML Parametershings to ConsiderML Macrosparing Thick- and Thin- Resistivity Values

faces


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etermined by the

erials based on the settings ects.



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The software automatically creates the appropriate PML matyou specified and assigns these materials to the selected obj




faces


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order to properly assign ll be treated uniformly, tem orientation.he PML objects in the

the PML objects in the

in the Propagation

y in the Propagation


etermined by the


pagation constants for he range you specify ies you intend to use in

uency range, you ions. However, a large ger solution times.

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User/Other/Guided> To specify the settings for a User/Other/Guided setup:

1. Select the PML objects to assign the PML materials to. Ina PML material, you must ensure that these objects can awith regard to the PML thickness and local coordinate sys



4. Enter the propagation constant at the minimum frequencyconstant at min. frequency field.

5. Enter the propagation constant at the maximum frequencconstant at max. frequency field.





Note: The frequency range corresponds to a range of prothe waveguides or transmission lines to terminate. There should correspond to the full range of frequencany subsequent solution. By indicating a broad freqincrease your flexibility in running subsequent solutrange will result in greater mesh refinement and lon





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faces


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nd thin-film resistivity values al resistor as a collection of

, keep the following points in

resistivity. After calculating

instead of material mpedance boundary.edance entered when you

ection.

L

aa

J

ction.

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Comparing Thick- and Thin-film ResistivityIn some instances, you may have to convert between thick- ato compare results. To do so, visualize the surface of the actusquares as shown in below:

When you are converting thick- and thin-film resistivity valuesmind:

• In Ansoft HFSS version 6, conductivity is used instead of the resistivity needed, enter it as a conductivity of 1/ρ.

• Thin-film resistors are defined using boundary conditions properties. Therefore, create a thin-film resistor using an i

• Rsurface corresponds to the real portion of the surface impdefine the impedance boundary.

You must reduce the following general relationship:

where ρ is the resistivity, to one of the following.

ab

J

L = the length of the resistor in the J dirArea (A) = ab

a

a

L

N = the number of squares in the J dire

R ρLA------=


eting Materialserial Attributescting Several Objects at ceelecting Objectsfectly Matched Layers

paring Thick- and in-film Resistivity Val-shick- to Thin-filmhin- to Thick-filmfaces


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square value:

per values of ρ and b as

e total circuit ohms, n of current flow on the r as two series resistors. 00 ohms/square to con-


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eting Materialserial Attributescting Several Objects at ceelecting Objectsfectly Matched Layers

paring Thick- and in-film Resistivity Val-shick- to Thin-Filmhin- to Thick-Filmfaces

Thick- to Thin-Film> To convert to ohms/square, assume the following:

• R is the total circuit resistance• L = Na

and use this equation to determine the appropriate ohms/

Thin- to Thick-Film> To convert from ohms/square, do the following:

1. Use the following equation to find the total resistance:

2. Use the total resistance in general equation to find the profollows:

Note: Depending upon the direction of current flow and thadjust ρ accordingly. For instance, given the directioright side of this figure, visualize that thin-film resistoIf that resistor’s resistivity is 50 ohms/square, use 1vert to a thick-film value.

Rsurface R N⁄=

R Rsurface N⋅=

R ρLA------ pNa

a b⋅----------= =

R ρNb-------=

RN---- ρ

b--- Rsurface= =


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d to be perfect conductors. m and is not assigned mate- model and fills any space ometric model as being

ide, create a single object in f the waveguide is automat-

cts not exposed to the back- inside a larger structure, r as well.

two dielectrics; on one side n the other side is the mate-l a thin conductor between pedance boundary.


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facesterface Between Two ielectrics

oundariesbjects Within Objects

SurfacesBy default, all surfaces touching the background are assume(The background, which is automatically created by the systerial characteristics, is the region that surrounds the geometricnot occupied by an object.) Therefore, visualize the entire geencased by a thin perfect conductor.

For example, to model a simple air-filled rectangular waveguthe shape of the waveguide and define it as air. The surface oically assumed to be a perfect conductor.

No special assumptions are made about the surfaces of objeground. For example, if an object defined as copper is placedAnsoft HFSS assumes that the surface of the object is coppe

Interface Between Two DielectricsNo special assumptions are made about the surface betweenof the surface is the material associated with one object and orial associated with the other. However, it is possible to modethe two objects by defining the surface to be a perfect E or im


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be overwritten by the ing the characteristics of air e with the Setup Bound-ary:

. This overwrites the perfect d the background.

r object, the material r object. Assign material .

object has been subtracted completely surrounded by a

ly assign it the character-


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facesterface Between Two ielectrics

oundariesbjects Within Objects

BoundariesIn some cases, the material that you specify for an object willboundaries that are assigned to them. In these cases, assignallows you to complete the Setup Materials step and continuaries/Sources step. For instance, to create a radiation bound

• Create a virtual object enclosing the model. • Assign it the material characteristics of air.

• Assign a radiation boundary to the virtual object’s surfaceE boundary that is assumed between the virtual object an

Objects Within Objects In cases where one object is entirely contained inside anotheassigned to the outer object stops at the boundary of the innecharacteristics to the two objects using the normal procedure

In cases where a void exists in an object (because a smaller out), the void is part of the background and is assumed to be perfect conductor.

Note: “Air” is an arbitrary selection. You could just as easiistics of a vacuum.


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