Ansoft HFSS waveguide

7/29/2019 Ansoft HFSS waveguide

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May2007

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The informat i on cont ained in th is document is subj ect t o change wit hout not ice.Ansoft makes no warranty of any kind wit h regard t o th is mater ia l , including,but not l im i t ed to , the im pl ied war rant ies of m erchantab i l i t y and f i t ness for a

part icular purpose. Ansoft shal l not be l iable f or errors cont ained herein or f orincidental or consequent ia l damages in connect ion wi t h t he furnishing, per f or-mance, or use of t h is mat er ia l .

2007 Ansof t Cor porat ion . Al l r igh t s r eser ved.

Ansoft Corporation

225 West St at ion Square DriveSuit e 200

Pit t sbur gh, PA 15219

USA

Phone: 412-261-3200

Fax: 412-471-9427

HFSS and Opti met r ics are regist ered t rademar ks or t radem arks of Ansoft Corpo-rat i on. Al l other t rademarks are the propert y of t heir respect ive owners.

New edi t ions of t h is manual incorporate al l m ater ia l updat ed since the previousedi t ion. The manual pr int ing dat e, w hich indicates t he manual s current edi t ion,changes when a new edi t ion is pr inted. Minor correct ions and updates t hat areincorporated at r epr int do not cause t he date t o change.

Update packages may be issued betw een edit ions and contain addit ional and/ or

repl acement pages t o be merged int o t he manual by t he user. Pages t hat arerearranged due t o changes on a previous page are not considered t o be revi sed.

Edi t i on Dat e Sof t w ar eVersion

1 January 2006 10. 0

2 May 2007 11. 0



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Getting Started with HFSS: A 20 Ghz Waveguide Combiner

iii

Please take a moment t o review how inst ruct ions and ot her useful i nfor -

mat ion are present ed in t his guide.

Procedures are pr esent ed as number ed l i st s. A single bul let indicat est hat t he procedure has only one st ep.

Bold t ype is used for t he fol l owing:

- Keyboard entr ies that should be typed in their ent i rety exact ly asshown. For example, copy file1 means t o type the word copy, t o

t ype a space, and then t o type file1.- On-screen p rom pt s and messages, names of opt ions and t ext boxes,

and menu comm ands. Menu commands are of t en separated by car-ats. For example, c l ick HFSS>Excitat ions>Assign>Wave Port .

- Labeled keys on t he comput er keyboard. For example, PressEnter means t o press t he key labeled Enter.

I tal ic t ype is used for t he fol low ing:

- Emphasis.

- The t i t les of publ i cat ions.

- Keyboard entr ies when a name or a variable m ust be t yped in placeof t he words in i t al ics. For exampl e, copy f il e name means totype the word copy, t o t ype a space, and t hen to t ype a f i le name.

The plus sign (+) is used bet ween keyboard keys to i ndicate t hat youshould press t he keys at t he same t ime. For exampl e, Press

Shift+F1 means t o press t he Shift key and t he F1 key at t he samet ime .

Toolbar but t ons serve as short cut s for executing comm ands. Toolbarbut t ons are displayed aft er t he comm and they execut e. For example,

On the Draw menu, c l ick Line means t hat you can c l ick theDraw Line toolbar but t on to execute t he Line command.

Alternatemethodsortipsarelistedintheleft

margininblueitalic

text.



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iv

To contact Ansoft t echnical support st aff in your geographical area,please log on to t he Ansoft corporat e website, h t t p : / / www.anso f t . com,c l ick the Contact but t on, and t hen c l ick Support . Phone num bers and e-mai l addresses for t he t echnical support st aff are l i st ed. You can alsocontact your Ansoft account m anager in order t o obtain t his inf ormat ion.

Al l Ansoft soft ware f i les are ASCII text and can be sent convenient ly by e-mai l . When report ing d i f f icu l t ies, i t is extrem ely helpfu l t o include very

specif i c inform ati on about w hat st eps wer e t aken or what st ages t hesimul at i on reached, including soft ware f i les as appl icable. This al low smore r apid and eff ect i ve debugging.

To access onl ine h elp f rom t he HFSS m enu bar, cl ick Help and select fr omt he menu:

Contents - c l ick here to open the content s of t he onl ine help. Seach - c l ick here t o open the search funct ion of t he onl ine help.

Index - c l ick here to open the index of t he onl ine help.

To access online help from the HFSS user interface, do one of the fol low-ing:

To open a help t opic about a specif ic HFSS me nu comm and, pressShift+F1, and t hen c l ick t he command or t oolbar icon.

To open a help t opic about a specif ic HFSS dial og box, open t he dia-log box, and t hen press F1.

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Contents-1

Table of Contents

TheSampleProblem ............................. 1-2

ResultsforAnalysis .............................. 1-3

OverviewoftheInterface .......................... 2-2

CreatetheNewProject ........................... 2-4

AddtheNewProject............................. 2-4

InsertanHFSSDesign...........................2-4

AddProjectNotes............................... 2-5

SavetheProject ................................ 2-5

SelecttheSolutionType .......................... 3-2

SetUptheDrawingRegion ........................ 3-3

Overviewofthe3DModelerWindow................ 3-3

CoordinateSystemSettings.......................3-4

UnitsSettings................................... 3-4

GridSettings...................................3-4

TransparencySetting ............................ 3-5

CreatetheGeometry ............................. 3-6

DrawtheWaveguideCombiner .................... 3-6

Table of Contents



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Contents-2

DrawthePolyline1Object........................ 3-6

VerifythePointsofPolyline1 ...................... 3-10

DuplicateandMirrorPolyline1 ..................... 3-12UnitePolyline1andPolyline1_1 ................... 3-13

RenamePolyline1 .............................. 3-15

ModifytheWaveguidesAttributes.................. 3-15

SweeptheWaveguide ........................... 3-17

SetUpBoundariesandExcitations ................. 4-2BoundaryConditions ............................. 4-2

ExcitationConditions............................. 4-2

AssignBoundaries............................... 4-3

AssignaFiniteConductivityBoundarytotheSide

Faces ........................................ 4-3

AssignaFiniteConductivityBoundarytotheBottomFace......................................... 4-7

AssignaPerfectESymmetryBoundarytotheTop

Face......................................... 4-10

AssignExcitations ............................... 4-13

AssignWavePort1 ............................. 4-14

AssignWavePort2 ............................. 4-15AssignWavePort3 ............................. 4-16

AssignWavePort4 ............................. 4-17

ModifytheImpedanceMultiplier ................... 4-18

VerifyAllBoundaryandExcitationAssignments.......4-19

SpecifySolutionOptions.......................... 5-2

AddaSolutionSetup............................. 5-2

AddaDiscreteFrequencySweep................... 5-5

ValidatetheProjectSetup ......................... 5-8

GeneratetheSolution ............................ 5-9

ViewtheSolutionData ........................... 5-10

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Getting Started with HFSS: A 20 Ghz Waveguide

Contents-3

ViewtheProfileData ............................ 5-10

ViewtheConvergenceData ...................... 5-12

ViewtheMatrixData ............................ 5-13

CreateModalS-ParametersReports ................ 6-2

CreateanS-ParametersReportofS11,S12,S13,

andS14....................................... 6-2

CreateanS-ParametersReportofS12andS14 .......6-3

CreateFieldOverlayPlots ......................... 6-5ScaletheMagnitudeandPhaseforthePorts ......... 6-5

CreateaMagEFieldOverlayCloudPlot ............. 6-6

CreateaPhaseAnimationoftheMagECloudPlot..... 6-7



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Contents-4



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Introduction 1-1

1Introduction

This Gett ing St art edguide is wr it t en f or HFSS beginners as wel l asexperienced users who are using version 11 for t he f i rst t ime. Thismanual guides you t hrough the setup, solut ion, and analysis of a t wo-

way, low -loss waveguide combi ner.By fol low ing the st eps in t his guide, you wi l l learn how t o perfor m t hef oll ow ing t asks in HFSS:

Draw a geomet ric model .

Modify a models design parameters.

Assign variabl es t o a m odel s design param et ers.

Specif y solut ion set t ings f or a design.

Validat e a designs set up.

Run an HFSS simulation.

Creat e a 2D x-y plot of S-paramet er r esult s.

Creat e a f ield overl ay plot of result s.

Creat e a phase animat ion of result s.



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1-2 Introduction

For t his problem, t he w aveguide comb iner i s a st andard WR42 modelwit h a four-port combining j unct i on. Each waveguide is 420 mi l s wi deand 170 mi ls high. This t ype of waveguide combiner is used t o combinet he out put power of t wo 20 GHz sol id stat e power ampl i f i ers (SSPA) wit ha very compact size and low insertion loss.

The out put s of t he SSPAs are f ed int o Port s 2 and 4 of t he w aveguide wi t ha 90-degree out-of -phase separat i on to st eer t he output power of t heampl i f iers to port 1. Port 3 of t he waveguide is t he iso lated port wheret he impedance mismatch at t he output (por t 1) is absorbed.

This problem is also described and analyzed in the fol lowing:

Arcioni, Paolo, Perr egrini , Luca, Bonecchi, Fulvio, Low-Loss WaveguideCombiners for Mult idevice Power Ampl i f iers, The Second Internat ionalConference on Elect romagnetics in Aerospace Applicat ions, Sept ember1991.

The geomet ry f or t his waveguide combiner pr oblem is shown below :

Port 4

Port 2

Combiningj unct ion Port 3

Waveguidesection

Port 1



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Introduction 1-3

Aft er set t ing up the w aveguide combiner m odel and generat i ng a solu-t ion , you w i l l :

Creat e Modal S-paramet er report s. Creat e a f i eld overlay cloud plot of t he magnit ude of E. Creat e an animat ion of t he mag-E cloud plot .

Time I t should t ake you approximat ely 2 hours t o work t hrough t he ent i r eguide.



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1-4 Introduction



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Creating the New Project 2-1

2Creating the New Project

This guide assum es t hat HFSS has alr eady b een i nstal le d as descri bedin the Installation Guide.

Your goals in t his chapter are as fol l ows:

Create a new proj ect .

Add an HFSS design t o t he pr oj ect .

Note I f you have not inst al led t he soft ware or you are not yet set up t o runt he soft ware, STOP! Fol low t he inst ruct ions in t he Installation Guide.

Time I t should take you approximately 10 minutes to work through thischapter.



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2-2 Creating the New Project

Below is an overview of t he maj or component s of t he HFSS int erf ace.

Displays det ails about all open HFSS proj ect s. Each proj ect

has it s own project t ree, w hich u l t imat ely inc ludes ageomet ric m odel and i t s boundaries and exci tat ions,mat eri al assignment s, analysis set ups, and analysis result s.

Displays err or, in f orm at ional, and warni ng messages f or t heact ive pro ject .

Displays solution progress information.

Menu bar

Toolbars

Status bar

History tree

Proj ect Managerwindow and thepro jec t t ree .

Message Managerwindow

Progresswindow

Propert ies

window

3D Modeler window



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Displays t he att r ibut es of a select ed obj ect i n the act ivemodel, such as t he obj ect s name, m ater ial assignment,orient at i on, color, and t ransparency.

Also displays inf ormat ion about a select ed comm and t hathas been carr ied out . For example, i f a circ l e was drawn,i t s command informat ion w ould inc lude t he commandsname, t he type of coordinat e syst em in w hich i t w asdrawn, the circ les center posi t ion coordinates, the axisabout which t he c i rc le was drawn, and t he size of i t sradius.

Displays t he drawing area of t he act ive model, along wit ht he h ist ory t r ee.

Displays al l oper at i ons and comm ands carr ied out on t heact ive model, such as information about the model sobj ect s and al l act ions associated w it h each obj ect, andcoordinate system information.

Provides various menus that enable you t o perf orm al l oft he HFSS t asks, such as managing proj ect f i le s, cust omi zingt he deskt op components, drawing obj ects, and set t ing andmodi fy ing al l pro j ect paramet ers.

Provides but t ons t hat act as short cut s for executing variouscommands.

Shows current actions and provides instructions.

Also, depending on t he command being carr ied out , t hest at us bar can display t he X, Y, and Z coordinat e boxes, t heAbsolute/Relative pul l -down l ist t o ent er a point sabsolut e or relat ive coordinat es, a pul l -dow n l ist t o specifya point i n cartesian, cyl indr ical , or spherical coordinates,and the act ive model s uni t sett ing.



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The first step in using HFSS to solve a problem is to create a project inwhich t o save al l t he data associated w it h the pr oblem. By default ,opening HFSS 11 creat es a new p roj ect named Proj ect nand insert s a newpr oj ect nam ed HFSSDesignn, where nis t he order in which each wasadded t o t he current session.

You can also create a new project and insert a design manually as fol-lows.

To add a new HFSS project:

Click File>New.

A new proj ect is l ist ed in the pro ject t ree in the Project Manager win-dow. I t is named proj ect nby defau l t , where ni s t he order in which t heproj ect was added t o t he current session. Proj ect def i ni t ions, such asboundaries and mat erial assignment s, are stored under t he proj ect nam e

in the proj ect t r ee.

The next st ep f or t his waveguide combiner pr oblem is t o insert an HFSSdesign int o t he new proj ect . By def ault , a design named HFSSDesignnw i t h t he t ype as [Dr iven Modal ] appears for t he current pr o ject .

To manual ly insert an HFSS design int o t he proj ect , do one of t he fol low-ing:

Click Project>Insert HFSS Design.

Right -c l ick on the pro j ect name in t he Project Manager window, and



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t hen cl ick Insert>Insert HFSS Design on the shortcut menu.

Click t he Insert HFSS Design t oolbar but t on .

A 3D Modeler window appears on t he deskt op and an HFSS Design icon is

added t o the pro j ect t ree, as shown below:

Next , ent er not es about your proj ect , such as i t s creat ion date and adescript ion of t he device being modeled. This is useful for keeping a run-ning log on t he pro ject .

To add not es t o the proj ect :

1 Click Edit >Edit Notes.

The Design Notes window appears.

2 Click in t he window and type your not es, such as a descript ion of t he

model and the version of HFSS in which it is being created.

3 Click OK t o save the notes wi t h the current pro j ect .

Next,saveandnamethenewproject.

Note To edit exist ing proj ect not es, double-cl ick Notes i n the proj ect t r ee.

Th e Design Notes window appears, i n which you can edi t t he pro ject snotes.



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ItisimportanttosaveyourprojectfrequentlybecauseHFSSdoes not

automaticallysavemodels.Savingfrequentlyhelpspreventthelossof

yourworkifaproblemoccurs.

To save the new proj ect :1 Click File>Save As.

The Save As dial og box appears.

2 Use t he f i le brow ser t o f ind t he d i rectory where you want t o save t he

f i l e .

3 Type the name wg_combiner i n the File name tex t box.

4 In the Save as type l i st , c l ick Ansoft HFSS Proj ect (.hfss) as t he cor-rect f i le extension for the f i le type.

When you create an HFSS project, i t is given a .hfss fi le extension by

defaul t and p laced in t he Proj ect d i r ectory. Any f i l es re lated t o t hat

pro j ect are st ored in t hat d i rect ory.

5 Click Save.

HFSS saves the project to the location you specified.

Now, you are ready to dr aw t he obj ects for t his waveguide combinerproblem.

Note For f urt her i nfor mat ion on any t opic in HFSS, such as coordinatesyst ems and grids or 3D Modeler comm ands or w indow s, you can viewthe context-sensit ive help:

Clickthe buttoninapop-upwindow.

Press .Thecursorchangesto .Clickontheitemwithwhichyouneedhelp.

Press F1. This opens the Help window. If you have a dialog open, the Helpopens to a page that describes the dialog.

Usethecommandsfromthe menu.



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Creating the Model 3-1

3 Creating the Model

This chapter shows you how t o create t he geomet ry for t hewaveguide combiner problem described earl ier. Your goals are as fol-lows:

Select t he solut ion t ype.Set up t he draw ing region.

Creat e the obj ect s t hat m akes up the w aveguide combiner m odel,which includes:

a. Drawingtheobjects.

b. Assigningcolorandtransparencytotheobjects.

c. Assigningmaterialstotheobjects.

You are now r eady to st art drawi ng the geometr y.

Time I t should take you approximately 30 minutes to work through thischapter.



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3-2 Creating the Model

Before you draw t he waveguide combiner m odel, f i rst you must specify asolut ion type. The default solut ion t ype is set i n theTools>Opt ions>HFSS Opt ions dialog. As you set up your model, t heavai lable opt ions wi l l depend on t he designs solut ion t ype.

To specify t he solut ion t ype:

1 Click HFSS>Solution Type.

The Solut ion Type dialog box app ears.

2 Select t he Driven Modal solut ion type.

The possibl e solut ion t ypes are described b elow.

3 Click OK t o apply the Driven Modal solut ion t ype t o your design.

Driven Modal For calcul at ing t he mod e-based S-param et ers of passive,high-frequency structures such as microstrips,waveguides, and t ransmission l ines, whi ch are drivenby a source.

DrivenTerminal

For calculat ing t he t ermi nal-based S-paramet ers ofpassive, high-frequency st ruct ures wi t h mult i -conduct ort ransmission l ine port s, w hich are driven by a source.

Result s in a t ermi nal-based descript ion rel ated t ovoltages and currents.

Eigenmode For calculat ing t he eigenmodes, or r esonances, of ast ruct ure. The Eigenmode solver f i nds t he resonantfr equencies of t he st ruct ure and the f ields at t hoseresonant fr equencies.



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The next st ep is t o set up t he drawing region. For t his waveguide com-biner problem, you wi l l decide the coordinate system, and specify theunits and grid settings.

The area containing t he model is cal led t he drawing region. Models aredrawn in the 3D Modeler window, w hich appears on t he deskt op whenyou insert a design into t he proj ect.

As shown below, t he 3D Modeler window consists of a grid and a history

t ree. The grid is an aid t o help visual ize the locat ion of obj ects. For m oreinformat ion about t he gr id, see Grid Set t ings on page 3-4.

The hist ory t ree displays al l operat ions and commands carr ied out on t heact ive model . For m ore informat ion about t he h ist ory t r ee, see Hist o ryt ree on page 2-3.

History

Grid



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For t his waveguide combiner pr oblem, you wi l l use the f ixed, def aultglobal coor dinat e syst em (CS) as t he w orki ng CS. This is t he curr ent CSwit h which obj ects being drawn are associated.

HFSS has t hree t ypes of coor dinat e syst ems that let you easily or ient newobject s: a globalcoordinate syst em, a relativecoordinate syst em, and afacecoordi nat e syst em. Every CS has an x-axis t hat l i es at a right anglet o a y-axis, and a z-axis t hat i s normal t o t he xy plane. The origin (0,0, 0)of every CS is located at t he int ersect i on of t he x-, y-, and z-axes.

Now, specif y t he drawing unit s for your model. For t his waveguide com-biner probl em, set t he drawing unit s t o mi l s (1 mi l = One t housandth ofan inch).

To set the drawing units:

1 Click Modeler>Units.

The Set Model Units dial og box appears.

2 Select mil f r om the Select unit s drop-dow n l ist , and ensure Rescale

to new unit s is cleared.

I f se lected, t he Rescale t o new uni ts option automatical ly rescales

t he gr id spacing to uni ts entered t hat are d i f f erent t han the set draw-

ing unit s.

3 Click OK t o accept mi l s as t he drawing unit s for t his model.

The grid displayed in t he 3D Modeler window is a drawing aid t hat helpst o visual ize the locat ion of obj ects. The points on the grid are div ided byt heir l ocal x-, y-, and z-coordinat es and grid spacing is set according t ot he current pro j ect s drawing uni ts.

Global CS The f ixed, defaul t CS for each new proj ect . I t cannot be edi ted

or deleted.

RelativeCS

A user-def ined CS. I ts origin and orient at i on can be set relat ivet o t he global CS, r elat ive t o anot her rel at i ve CS, or relat ive t oa geometric feature. Relative CSs enable you to easily drawobject s t hat are located re lat ive t o other object s.

Face CS A user- def ined CS. It s ori gin is specif ied on a pl anar obj ectface. Face CSs enable you to easily draw objects that arelocat ed re lat ive t o an obj ect s face.



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For t his waveguide combiner proj ect, i t is not necessary to edi t any oft he gr id s defaul t propert ies.

To edit t he grid s propert ies, c l ick Grid Settings on the View menu to

contr ol t he grids t ype (cart esian or polar), st y le (dot s or l i nes), densit y,spacing, or visibi l i t y.

Set t he defaul t t ransparency for object s t o 0.4.

To set t he default t ransparency for new obj ect s:

1 Click Tools>Options>Modeler Options.

The 3D Modeler Options window appears.2 Click t he Display tab .

3 I f i t is not a l ready there, m ove the Default transparency sl ider t o the

f i f t h l ine (which is a tr ansparency of 0.4), and t hen cl ick OK.



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The geometry for this waveguide combiner consists of a single standardWR42 waveguide combiner obj ect w it h a four -port , l ow-l oss combining

j unct ion. Each w avegu ide is 420 m i l s w ide an d 170 m i l s h igh .

Since thi s model w i l l be symm et ric about t he xz plane, f i rst you wi l ldraw t he lef t -hal f o f t he st ructure and t hen dupl icat e i t t o create t her ight -side and complete t he model .

To help reduce t he size of t his model, you wi l l assign a perf ect E symm e-t ry boundary to t he top face of t he waveguide combiner t o spl i t i t sheight in hal f (85 mi ls). This enables you to m odel only part of a st ruc-

t ure, t hereby shortening the solut ion t ime.For a det ai led descript ion about t his waveguide com biner, see The Sam-ple Problem on page 1-2.

You wi l l create t he waveguide combiner by f i rst draw ing i ts lef t -side andt hen dupl icat ing i t t o creat e t he r ight-s ide of t he model . Then, you wi l l

uni t e t hese 2-dimensional (2D) sheet obj ects (geomet ric obj ect s contain-ing surf ace area but no volume) t o make t he single waveguide combinerobject . Next , you wi l l sweep t h is object in t he z-axis d i rect ion t o creat et he f inal 3D waveguide combi ner.

Draw the Polyline1 Object

The f i rst object you wi l l draw is t he lef t -hal f o f t he waveguide combiner,which is created by draw ing a polyl i ne obj ect consist ing of 25 points.

This wi l l r esult in a 2D sheet obj ect wi t h a default name of Polyl ine1.To draw Polyl ine1, you can use one of two methods.

Method 1: Draw a Polyline and Edit the Point Coordinates

The f i rst, more f orgiving met hod, is to begin by drawing a closed polyl inewith 25 mouse clicks. You then use the basic approach described in the Veri fy the Point s of a Polyl ine sect ion t o enter t he correct coordinatesfor each point v ia the CreateLine proper it es wi ndow f or each segment.

1 Click Draw>Line, or c l ick the Draw line but t on on the t oolbar.

2 Cl ick a point at t he or igin, and increment a count of c l icks f r om t he

ini t ial c l ick to 25, for convenience fol lowing a counter-clockwise

movement that places the last c l ick back at the origin.

3 Right-cl i ck to display the short cut menu.

4 Click Done.



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This displays t he propert ies window for t he newly creat ed polyl ine in

t he docked propert ies window.

5 Go to t heVeri fy the Point s of a Polyl ine sect ion and fo l low t he pro-

cedure to enter the correct coordinates for each segment.

Method 2: Enter the Point Coordinates for Each Point

The second met hod is more di rect , but is less for giving. In t his case, youenter the point coordinates for each vert ice of the 25 segment polyl inein sequence:

1 Click Draw>Line, or c l ick the Draw line but t on on the t oolbar.

The st atus bar now prompt s you to enter t he f i rs t point of t hepolyl ine.

2 Pre ss th e Tab key to move t o the X box, and then select t he f i rst point

of t he l ine by enteri ng t he fol low ing values in t he coordinat e boxes,

pressing Tab t o move t o the next coordinat e text box:

3 Press the Enter key to accept t h is point .

You can delet e t he last point you entered by r i ght-cl icking in t he 3D

Modeler window and t hen c l icking Back up on the shortcut menu.

4 Cont inue wi t h t h is same met hod to enter t he fo l lowing 24 points that

remain:

X coordinat e 0

Y coordinat e 0

Z coordinat e 0

Note Skip t he f i r st point , s ince you just ent ered i t s coordinates (0, 0, 0) int he preceding steps.

Point X Coordinate Y Coordinate Z Coordinate

1 0 0 0

2 0 -53 0

3 -147 -53 0

4 -474 -367 0

5 -474 -710 0

6 -944 -710 0

7 -944 -1130 0

8 -369 -1130 0


G i S d i h HFSS A 20 Gh W id C bi


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5 Right-cl i ck in t he 3D Modeler window, and cl ick Close Polyli ne on

t he shortcut menu.

The 2D polyl ine obj ect appears in t he drawing region.

The obj ect is named Polyl ine1 by default , as displayed in t he Proper-

ties window.

9 -27 -792 0

10 -27 -467 0

11 83 -467 0

12 146 -433 0

13 255 -433 0

14 337 -411 0

15 427 -411 0

16 506 -523 0

17 682 -523 0

18 915 -683 019 1562 -683 0

20 1562 -263 0

21 1073 -263 0

22 858 -53 0

23 612 -53 0

24 612 0 0

25 0 0 0

Note Objects are automatical ly selected immediately after being drawn sot hat you can inst ant ly v iew t he selected obj ect s defaul t a t t r ibut es in

t he Properties window.




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6 Press Ctrl+D t o f i t the obj ect in the drawing region.

Your complet ed lef t -hal f of t he waveguide combiner should appear in

t he 3D Modeler window, as shown below:




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Verify the Points of Polyline1

Before you dupl icat e t he object Polyline1 t o creat e the r ight-side of t hewaveguide combiner, i t is important that you make sure al l the points

you ent ered are correct .The image below displays al l t he point locat ions requir ed for t he obj ectPolyline1:

To veri f y t he point s:

1 In the h ist ory t r ee, c l ick t he p lus (+) symbol t o t he lef t o f Sheet s t o

expand t he t ree st ruct ure t o see Unassigned. Expand t he st ruct ure

under Unassigned to see Polyl ine1. Expand the structure under

Polyl ine1 t o see Creat e Polyl ine. Expand t he st ruct ure under




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Polyline1 t o see the tw enty- f ive CreatePolyline objects .

2 Click t he f i r st CreateLine object in the l ist t o view t he coordinat evalues t hat you enter ed for point 1 (0, 0, 0) and point 2 (0, -53, 0).

These values are di splayed i n t he Properties wi ndow, as shown

below:

3 Veri f y that t he values for t hese points are correct .

Point X Coordinate Y Coordinate Z Coordinate

1 0 0 0

2 0 -53 0

3 -147 -53 0

4 -474 -367 0

5 -474 -710 0

6 -944 -710 0

7 -944 -1130 0

8 -369 -1130 0

9 -27 -792 0

10 -27 -467 0

11 83 -467 0

12 146 -433 0




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g g


4 To edi t an incorrect point value:

a. Inthehistorytree,selectthe objectyouwanttoedit.

b. Inthe window,enterthecorrectvaluesinthe column.

ThevalueenteredforPoint2automaticallyappliestothePoint1forthe

nextsegment.Therefore,youneedonlyeditPoint2insubsequentCre-

ateLinewindows.

Asyouenterthevalues,thedisplayofthesegmentupdates.Youmay

needtouse toresizethedisplayinthe3Dwin-

dow.

c. Press toapplythenewvaluestothemodel.

5 Cont inue wi t h t h is same met hod to ver i f y t he values for a l l t heremaining point s.

Duplicate and Mirror Polyline1

Next , you wi l l dupl icate and mirror t he object Polyline1 object about aspecif ied plane to create the r ight-hal f of the waveguide combiner.Remem ber, t his is possibl e because t he w aveguide com biner is symm et ri cabout t he xz plane. This wi l l result in a 2D sheet obj ect w it h a default

name of Polyline1_1.

To dupl icate t he object Polyline1:

1 Select t he object Polyline1 by e i ther c l ick ing on i t in t he 3D Modeler

w indow or c l ick ing i t s name in t he h ist ory t ree.

2 Click Edit>Duplicate>Mirror .

3 Press Tab to move to the X box, and then ent er (0, 0, 0) t o specify

13 255 -433 0

14 337 -411 0

15 427 -411 0

16 506 -523 0

17 682 -523 0

18 915 -683 0

19 1562 -683 0

20 1562 -263 0

21 1073 -263 0

22 858 -53 023 612 -53 0

24 612 0 0

25 0 0 0




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t he point on t he p lane on which you want t o mirror t he obj ect .

A l ine drawn f r om t h is point t o the m irror p lane wi l l be perpendicular

t o the p lane.

4 Press Enter .

5 Press Tab t o move to t he dY box and enter 1 t o specify a norm al point

on the plane.

6 Press Enter .

The object Polyline1_1, a dupl icate of obj ect Polyline1, ap pears on

t he p lane you speci f ied, or iented according to t he normal point you

specified, as shown below:

Unite Polyline1 and Polyline1_1

Now t hat you have successful ly creat ed bot h halves of t he waveguidecombiner, you wi l l un i t e, or j o in, t hem t o make the s ingle waveguidecombiner object .

To unit e bot h halves of t he waveguide combiner :

1 Select Polyline1.

2 Press and hold down Ctrl t o also select Polyline1_1.

Polyline1 an d Polyline1_1 should now both be selected. To verify,

both obj ects should be h ighl ighted i n t he h ist ory t ree, and t he st atus




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bar should indicate t hat t he number of object s selected is two.

3 Click 3D Modeler >Boolean>Unit e.

The new obj ect t hat is creat ed inheri t s i t s propert ies (name, color,

boundary, and material assignment) from the f i rst object selected

(Polyline1) .The result ing single, new obj ect appears in t he 3D Modeler window,

as shown below :

Note By defaul t , t he objects being jo ined to t he f i rst object se lected are notpreserved f or lat er use.

For t his waveguide combi ner probl em, you do not need t o preserve anyobject s for l a ter use. However, i f you want t o keep a copy of t heobject s being j o ined to t he f i rst object se lected, do one of t hefo l lowing:

Copytheobjects,andthenpastethembackintothedesignafterunitingthem.

Onthe menu,pointto ,andthenclickinthe dialogbox.This

optioninstructsHFSStoalwayskeepacopyoftheoriginalobjectsbeing

joined.




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Rename Polyline1

Next , change t he defaul t name of t he new, uni t ed object t o speci fy t hati t is t he waveguide combiner obj ect .

To modif y t he name of Polyline1 ob jec t :1 Under t he Attribute tab o f the Properties window, cl ick Polyline1 i n

t he Name row.

2 Type waveguide t o rename t he obj ect , and then press Enter t o

accept t he new name.

Modify the Waveguides Attributes

The next st ep in creat i ng t he waveguide is t o modif y i t s defaultat t r ibut es t hat are d isplayed in t he Properties window, which includesassigning a color and t ransparency, and veri f y ing the current mat erialassignment.

Assign a Color to the Waveguide

To assign a color t o t he w aveguide:

1 Select the object waveguide, i f i t is not alr eady select ed.

2 Under t he Attribute tab o f the Properties window, c l ick Edit i n the

Color row.

The Color palette appears.

3 Select the basic color blue (RGB settings 0, 0, 255) from the Color

palet t e, and then c l ick OK t o assign the color t o t he obj ect

waveguide.

Whi le t he w aveguide i s select ed, i t ret ains t he select ion color. To seet he assigned color, unselect t he waveguide by cl icking a locat ion in

t he drawing window of f t he waveguide.

Assign a Transparency to the Waveguide

To assign a t ransparency l evel t o t he w aveguide:

1 Select the object waveguide, i f i t is not alr eady select ed.

2 Under t he Attribute tab o f the Properties window, c l ick the defaul tvalue 0.4 i n the Transparency row.

The Set Transparency wi ndow appears.

3 Move the sl ider t o t he r ight t o increase t he t ransparency level, st op-

ping when t he value is 0.7.

4 Click OK.




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The t ransparency is now set t o .7, which appears as t he new value in

t he Transparency row af t er i t is set .

5 Click out side t he object , on t he grid background, t o deselect

waveguide and view the resulting color and transparency assign-ments.

Your waveguides color and transparency should resemble the one

shown bel ow:

Verify Lighting Attributes are Disabled

I f you want, you can change t he default ambient and dist ant l ight source

propert ies at t his t ime, t hough i t is not necessary for t his waveguidecombiner problem.

To veri f y l ight i ng at t r ibut es are disabled:

1 Click View>Modify At t r ibutes>Lighting.

The Light ing Propert ies dial og box appears.

2 Ver i fy tha t t he Do not use lighting opt ion is disabled. Clear t his

opt ion i f i t is se lected.

3 Click OK or Cancel , depending on whet her or not you had t o c lear the

l ight ing opt ion.




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Sweep the Waveguide

Next , you must sweep t he 2D obj ect waveguide along a vect or t o createa 3D sol id obj ect as t he f i nal waveguide combiner model.

To sweep the waveguide along a vector:1 Select the object waveguide, i f i t is not alr eady select ed

2 Click Draw>Sweep>Along Vector .

3 Draw t he vect or you want t o sweep t he object a long:

d. Enter( , , )inthecoordinateboxestospecifythestartpoint,andthen

press .

e. Tabintothe boxandenter tospecifytheendpoint,andthenpress

.

The Sweep along vector dial og box appears.

4 Enter 0 i n the Draft angle tex t box.

This is t he angle to w hich the pr of i l e is

expanded or contr acted as i t is swept .

5 Select Round f r om the Draft t ype

pul l -down l ist .This draft t ype appl ies rounded edges

to t he new ob jec t .

6 Click OK t o complet e the sweep.

Your com plet ed 3D object waveguide should r esemb le t he one shown

below:




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7 Click File>Save, o r c l i ck t he Save a proj ect t oolbar but t on , t o

save t he geomet ry.

Now you are ready t o assign al l boundaries and exci t atons to t he

waveguide combiner.



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Setting Up the Problem 4-1

4 Setting Up the Problem

Now t hat you have creat ed t he geomet ry and assigned al l m ater ialsfor t he waveguide combiner problem, you are ready to def ine i t sexci t at i ons and b oundaries.

Your goals for this chapter are to:Defi ne t he boundary condit ions, such as t he locat i ons of f ini t econductiv i t y boundaries.

Defi ne t he wave port s t hrough which t he signals ent er and leavet he waveguide combiner.

Veri f y t hat you correct ly assigned the b oundaries and exci tat ionsto t he mode l .

Now you are ready to set up t he problem .

Time I t should t ake you approximat ely 15 minut es t o work t hrough t his chapter.




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4-2 Setting Up the Problem

Now t hat you have created t he waveguide combiner m odel and definedit s propert ies, you must d ef ine t he boundary and exci t at i on condit ions.

These condit ions specify t he exci t at i on signals ent ering t he st ruct ure,t he behavior of el ectr ic and magnet ic f i elds at various surf aces in t hemodel, and any special surf ace characterist ics.

Boundaries specify t he behavior of m agnet ic and elect r ic f ields at vari-ous surf aces. They can al so be used t o ide nt if y special surfaces such as

resist ors whose character ist ics di f fer fr om t he default .The fol low ing tw o types of boundary condit i ons wi l l be used for t hiswaveguide combiner problem:

Wave port s def ine surf aces exposed t o non-exist ent mat erials (general lythe background or materials def ined to be perfect conductors) through

which exci t at i on signals ent er and leave the st ruct ure.Wave ports represent places in t he geomet ry t hrough which exci tat ionsignals ent er and leave t he st ruct ure. They are used when m odel ing st r ipl ines and ot her w aveguide struct ures, such as t his waveguide com binerproblem. Wave ports are typical ly placed on the perfect E interfacebetw een the 3D object and the background to pr ov ide a window t hatcouples t he model dev ice to t he external wor ld.

Finiteconductivity

This t ype of boundary repr esent s an im perf ect conductor. HFSSdoes not comput e t he f ie ld inside t hese object s; t he f in i t econduct iv i t y boundary approx imates t he behavior of t he f ie ld att he surf aces of t he obj ect s. Any skin-eff ect losses wi l l be

proper ly t aken int o account .For t h is waveguide combiner problem, a f in i t e conduct iv i t yboundary is assigned t o t he side f aces (excl uding t he four port s),and the bot t om face of t he model .

Symmetry In st ruct ures t hat have an elect romagnetic pl ane of symm et ry,such as t his waveguide combi ner model , t he problem can besimpl i f ied by model ing only one-hal f of t he model and ident i f y ing

the exposed surface as a perfect H or perfect E boundary.For t his waveguide combiner pr oblem, a perfect E symm et ryboundary is assigned to t he t op face of t he model.



For t his waveguide combiner problem a wave port is assigned t o each


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For t his waveguide combiner problem , a wave port is assigned t o eachend-face of t he model s four waveguide sect i ons.

First, you wil l assign all boundary conditions to the model. These assign-ment s include t wo f ini t e conduct iv i t y boundaries and one perf ect E sym-met ry boundary.

To review infor mat ion on t he t ypes of boundaries you wi l l assign, see Boundary Condit ions on page 4-2.

Assign a Finite Conductivity Boundary to the Side Faces

Fini t e conductiv i t y boundary to al l t he waveguide combiner s side f aces,excludingt he port faces.

As discussed in Boundary Condit ions on page 4-2, f i n i te conduc t i v i tyboundaries represent im perf ect conductors. At such boundaries, t he fol-lowi ng condit ion holds:

where Et ani s t he component of t he E-f ie ld t hat is tangent ia l t o t he sur face.

Ht ani s t he component of t he H-f ie ld t hat is tangent ia l t o the sur face.

Zsi s t he sur f ace im pedance of t he boundary, , w here

istheskindepth, ,oftheconductorbeingmodeled.

istheangularfrequencyoftheexcitationwave.

istheconductivityoftheconductor.

isthepermeabilityoftheconductor.The fact t hat t he E-f i eld has a tangential component at t he surf ace ofimperfect conductors simulates the case in which the surface is lossy.

The surf aces of any obj ects def ined t o be non-perfect conductors areautom ati cal ly set t o f ini t e conduct iv i t y boundaries. HFSS does notat t empt t o comput e the f ie ld inside these objects ; the f in i t e conduct iv-i t y boundary approximat es t he behavior of t he f ield at t he surf aces of

t he obj ects.The f ini te conductiv i ty boundary condit ion is val id only i f the conductorbeing modeled is a good conductor, t hat is, i f t he conductor s t hickness ismuch larger t han the skin dept h in t he given fr equency range.

To assign a f ini t e conducti v i t y boundary t o t he side f aces of t hewaveguide combiner :

1 Right-cl i ck in the 3D Modeler window, t hen c l ick Select Faces on the

Eta n Z n Hta n( )=

1 j+( ) ( )

2 ( )



shortcut menu


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shortcut menu.

In t his mode you can select or de-select an obj ect s faces inst ead of

t he ent i r e object . When the mouse hovers over a face in the 3D Mod-

eler window, t hat face is out l ined, w hich indicates t hat i t w i l l beselect ed when you cl ick.

2 Ult imat ely , you want t o select a l l o f t he side faces of t he object

waveguide, except t he port faces. Here, you do not seek t o select

t he top or bot t om f aces. However, g iven the number and posi t ion of

t he f aces, i n t his case it is easier t o use Edit>Select All, and t hen use

Ctrl-click t o de-select t he four por t f aces, and t he top and but t om

faces. You wi l l need to rot ate t he model t o complete t he process.

Wit h Face select ion mode on, c l ick Edit>Select All. This high-l ights al l f aces on the obj ect .

Press and hol d dow n Ctrl and cl ick to de-select t he top f ace andt wo visible port faces.

Press and hol d dow n Alt and drag the mouse t o rotat e t he modelt o a posi t ion w here you can select t he desired side f aces.

Pre ss and hol d Ctrl and cl ick to deselect t he rotated bot t om faceand the rem aining port faces.

Al l side f aces of t he waveguide combiner are select ed.

3 On t he HFSSmenu, c l ick Boundaries>Assign>Finite Conductivity.



The Fini te Conducti vit y Boundary wi ndow appears


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The Fini te Conducti vit y Boundary wi ndow appears.

4 Select t he Use Material check box, and c l ick the mat er ia l but t on

(wher e t he default vacuum is displayed).

The Select Definition window appears. By default , this material

brow ser l ists al l m ater ials in t he global m ater ial l ibr ary, as wel l as t helocal mat er ia l l ibrary for t he current pro j ect , which is a subset of t he



global l ibrary.


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global l ibrary.

5 Select aluminum f rom t he l ist of mat er ia ls, and t hen cl ick OK.

The Fini te Conducti vit y Boundary window reappears.

The conductiv i ty and permeabi l i ty values for aluminum are now

assigned to t he f i ni t e conductiv i t y boundary.

6 Clear Infinite Ground Plane i f i t is select ed.

I f se lected, t he Infinit e Ground Plane opt ion simul ates t he eff ects of

an inf ini t e ground plane. This opt ion only aff ects the calculat ion of

near- and far-field radiation during post processing. The 3D Post Pro-cessor models the boundary as a f ini t e port ion of an inf i ni t e, per-

fect ly conduct ing p lane.

7 Click OK t o accept t he defaul t name FiniteCond1 and apply the

boundary.

The result ing f ini t e conduct iv i t y boundary is appl ied t o the side faces

of t he object w aveguideand now appears as a subent ry of



Boundaries in t he pro ject t ree, as shown below:


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p j ,

By default , t he geomet ry, name, and vect ors for t he boundary are al lshown in t he 3D Modeler wi ndow. For t his waveguide combiner p roblem ,i t is not necessary t o edi t any of t he boundarys visual izat ion def ault set -tings.

Assign a Finite Conductivity Boundary to the Bottom Face

Next , assign a f in i t e conduct iv i t y boundary to t he bot t om f ace of t hewaveguide combiner, using t he same procedure you j ust fol l owed t oassign a f ini t e conducti v i t y boundary t o t he side f aces.

Note To edit a boundary s visualizat ion set t ings:

1. Click ifyouwanttoshoworhide

boundaries.

2. Clearthe , ,or selectionof

boundariesthatyouwanttohidefromview.Selecttheoptionsyouwant

toshowinthe window.

3. Click .

Fini te Conductiv i tyboundary added as asubent ry of

Boundaries

Fini t e Conductiv i t y boundaryassigned t o t he side f aces

Propert ies of t he

f in i te conduct iv i tyboundary



To assign a f i ni t e conductiv i t y boundary t o the bot t om f ace of t he


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waveguide:

1 I f i t is st i l l selected, deselect the f ini te conductiv i ty boundary you

j ust assigned t o t he side f ac es.2 In Select Faces mode, do one of t he fo l lowing to select t he bot t om

face of t he obj ect waveguide:

Press and hol d dow n Alt and drag the mouse t o rotat e t he modelt o a posi t ion where you can select t he bot t om f ace.

Cl ick t he top f ace, and then c l ick Next Behind on the short cutmenu, or press B on the keyboard, t o select t he bot t om face.

The bott om f ace of t he waveguide combiner is select ed.

3 On t he HFSSmenu, c l ick Boundaries>Assign>Finite Conductivity.

The Fini te Conducti vit y Boundary wi ndow appears.

Hint You can also assign boundaries by selecting the object or object face to

which you want t o assign the boundary, and t hen doing one of t hefo l lowing:

Right-clickinthe window,pointto ,andthenclicktheboundarytypeyouwanttoassign.

Right-clickon intheprojecttree,pointto ,andthenclicktheboundarytypeyouwanttoassign.



4 Select t he Use Material check box, and c l ick the mat er ia l but t on


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(wher e t he default vacuum is displayed).

The Select Definition window appears.

5 Select aluminum f rom t he l ist of mat er ia ls, and c l ick OK. The Fini te Conducti vit y Boundary window reappears.

The conductiv i ty and permeabi l i ty values for aluminum are now

assigned t o t his f ini t e conducti v i t y boundary.

6 Clear Infinite Ground Plane i f i t is select ed.

7 Click OK t o accept t he defaul t name FiniteCond2 and apply t he

boundary.

The resul t ing f in i te conduct iv i t y boundary is appl ied to t he bot t om

face of t he obj ect waveguide.



Assign a Perfect E Symmetry Boundary to the Top Face


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HFSS has a boundary cond it ion specif icall y for symm et ry pl anes. Inst eadof def ining a perf ect E or perf ect H boundary, you def ine a perfect E or

perfect H symmet ry p lane.When you are def ining a symm et ry plane, you must decide whi ch type ofsymm et ry boundary should be used, a perf ect E or a perfect H. In gen-eral , use the fol lowing guidel ines to decide which type of symmetryplane to use:

I f t he symm et ry is such that t he E-f i eld is normal t o the symm et ryplane, use a perf ect Esymmetry plane.

I f t he symm et ry is such that t he E-f ield is t angent ial t o the symm et ryplane, use a perf ect Hsymmetry plane.

The simpl e tw o-port rect angular waveguide shown below i l lust rat es t hedif fer ences bet ween t he tw o types of symm et ry planes. The E-f i eld oft he dominant mode signal (TE10) is shown . The w aveguide has t wo pl anesof symm et ry, one vert ical ly t hrough the center and one horizontal ly.

The horizont al plane of symm et ry is a perfect Esurf ace. The E-f i eldis normal and t he H-f i eld is t angent ial t o that surf ace.

The vert i cal plane of symm et ry is a perfect Hsurf ace. The E-f i eld ist angent ia l and H-f ie ld isnormal t o t hat sur face.

Since t he E-f ield is symm et ric t o t he height of t he waveguide combinermodel in t his guide, t he height of t he waveguide has been spl i t in hal f inorder t o place a perf ect E symm et ry boundary on the t op face.

Electric field of TE10 Mode

Perfect E symmetry plane

Perfect H symmetry plane



Next , you wi l l assign a perf ect E symm et ry boundary to t he t op face oft he waveguide combiner ( t he symmet ry plane for t he model )


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t he waveguide combiner ( t he symmet ry p lane for t he model ) .

To assign a symm et ry boundary t o t he t op f ace of w aveguide:

1 I f i t is st i l l selected, deselect the f ini te conductiv i ty boundary youj ust assigned.

2 In Select Faces mode, select t he top face of t he obj ect waveguide.

The t op face of t he waveguide is select ed.

3 On t he HFSSmenu, c l ick Boundaries>Assign>Symmetry.

The Symmetry Boundary dial og box appears.4 Select Perfect E as t he symm et ry t ype.

5 Do the fo l lowing to edi t t he impedance mul t ip l ier :

a. Click Impedance Multiplier.

The dialogboxappears.

b. Enterthevalue inthe box,andthenclick .



6 Click OK t o accept t he defaul t name Sym1 and apply the boundary.

Th lt i f t E t b d dit i i i d t


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The result ing perf ect E symm et ry boundary condit i on is assigned t o

t he top face t he obj ect waveguide, as shown below:



N i l l i l l i i h id bi d l


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Now you wi l l assign al l exci t at i ons t o t he waveguide combiner model.These exci t at i ons include w ave port s assigned t o each end f ace of t he

models four waveguide sections, as shown below:

Wave ports represent places in t he geomet ry t hrough which exci tat ionsignals ent er and l eave t he st ruct ure. HFSS assume s t hat each wave por tyou define is connected t o a semi-i nf ini t ely long waveguide t hat has t hesame cross-sect i on and mat erial p ropert ies as t he port .

When solving f or t he S-param et ers, HFSS assumes that t he st ruct ure i sexci t ed by the natur al f iel d patt erns (modes) associated w it h thesecross-sect ions. The 2D f iel d solut ions generat ed f or each wave port serveas boundary condit ions at t hose port s for t he 3D problem . The f i nal f iel dsolut ion computed m ust mat ch the 2D f ie ld pat t ern at each port .

For t his waveguide combiner model, you wi l l assign four w ave ports tot he locat i ons shown in t he above image.

Port 1

Port 2

Port 3

Port 4



The funct i on of each wave port in t his waveguide combiner m odel are asfol lows:


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fol lows:

Assign Wave Port 1

To assign wave port 1:

1 Deselect t he perf ect E boundary you j ust assigned, i f i t is st i l l

selected.

2 In Select Faces mode, select t he face of por t 1.

3 On t he HFSSmenu, c l ick Excitations>Assign>Wave Port .

The Wave Port wizard appears.4 In the Wave Port :General st ep, accept t he defaul t name WavePort1,

and then cl ick Next .

5 In the Wave Port :Modes st ep, accept t he defaul t set t ings, and then

cl ick Next .

6 In the Wave Port:Post Processing step, accept the default sett ings,

and then cl ick Finish t o complete t he wave port assignment for por t

1.

WavePort1 is assigned t o t he w aveguide and now appears as a suben-

The output por t t hat is fed t he out put power of t he sol id st ate

power amp l i f iers fr om port s 2 and 4.The port in w hich t he out put of a SSPA is fe d.

The iso lated port where t he impedance mismatch at t he output(port 1) is absorbed.

The port in w hich t he out put of a SSPA is fed, wit h a 90-degreeout- of-phase separat i on to port 2.



t r y of Excitations in t he pro ject t ree, as shown below:


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Assign Wave Port 2

To assign wave port 2, you w i l l use t he same pr ocedure you j ust fol lowedt o assign wave port 1, but w i t h t he addi t ion of an integrat ion l ine.

When HFSS comput es t he exci t at i on f ield pat t ern at a port , t he direct i onof t he f ie ld at wt = 0 is arb i t r ary ; t he f ie ld can a lways point in one of at

least two direct ions.For both w ave port 2 and wave port 4, you must cal ibrat e t he port r e la-t ive to some r eference or ient at ion by def in ing an integrat ion l ine in t heupdi rect ion.


1 Deselect WavePort1 t hat you j ust assigned, i f i t is st i l l selected.



The Wave Port wizard appears.

4 In the Wave Port :General st ep, accept t he defaul t name WavePort2,


5 In the WavePort:Modes step , c l ick in the Integrat ion Line l is t , and

Wave por tassignmentadded as asubentr y ofExci tat ions

Propert ies of t he

wave port Port 1assigned



t hen select New Line.

The Wave Port wizard di sappears whi l e you draw t he vector.


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6 Def ine t he integrat ion l ine:

a. Selectthestartpointbyclickingthecenterofthebottomlineontheface.Yourcursorwillappearasatrianglewhenitisatthisexactlocation.

b. Selecttheendpointbyclickingthecenterofthetoplineontheface,

whichisdirectlyverticaltothestartpointyoujustselected.Again,your

cursorwillappearasatrianglewhenitisatthisexactlocation.

The endpoint def i nes t he d i rect ion and lengt h of t he integrat ion l ine.

The Wave Port wizard reappears at t he WavePort:Modes step.

7 Click Next . 8 In the Wave Port:Post Processing step, accept the default sett ings,


2.

WavePort 2, w i t h i t s in tegrat ion l ine, is shown below:

Assign Wave Port 3

To assign wave port 3, you w i l l use t he same pr ocedure you f ol low edwhen you assigned wave por t 1.



2In Select Faces mode, select t he face of por t 3.





5 In the Wave Port :Modes st ep, accept t he defaul t set t ings, and then



cl ick Next .

6 In the Wave Port:Post Processing step, accept the default sett ings,


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g p, p g ,


1.WavePort3 is assigned t o t he w aveguide and now appears as a suben-

t r y of Excitations i n the proj ec t t ree .

Assign Wave Port 4

To assign wave port 4, you w i l l use t he same pr ocedure you f ol low edwhen you assigned wave por t 2.




3 Zoom in on the f ace of por t 4.





6 In the WavePort:Modes step , c l ick in the Integrat ion Line l is t , and

t hen select New Line.


7 Def ine t he integrat ion l ine:

a. Selectthestartpointbyclickingthecenterofthebottomlineontheface.

Yourcursorwillappearasatrianglewhenitisatthisexactlocation.b. Selecttheendpointbyclickingthecenterofthetoplineontheface,

whichisdirectlyverticaltothestartpointyoujustselected.Again,your

cursorwillappearasatrianglewhenitisatthisexactlocation.

The endpoint def i nes t he d i rect ion and lengt h of t he integrat ion l ine.

The Wave Port wizard reappears at t he WavePort:Modes step.

8 Click Next .

9 In the Wave Port:Post Processing step, accept the default sett ings,and then cl ick Finish t o complete t he wave port assignment for por t

4. WavePort4, w i t h i t s int egrat ion l ine, is assigned to t he waveguide



and now appears as a subent ry of Excitations i n the proj ect t r ee .

Note To edit a wave port assignment:


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Modify the Impedance Multiplier

Because you defined a symm et ry plane (al low ing the m odel of a struc-t ure t o be cut in hal f ) , t he impedance comput at ions must be adjust ed byspecify ing an impedance mul t ipl ier.

In cases such as t his waveguide combiner p roblem , where a perf ect Eplane of symmetry spl i ts a structure in two, only one-half of the vol tagedi f f erent ia l and one-hal f of t he power f low can be computed by t he sys-tem.

Therefore, s ince the impedance, Zpv, is given by ,

t he computed value is one-half t he desired value. An impedance mult i -pl i er of 2 must be specif ied i n such cases.

To edi t t he impedance mul t ip l ier :

1 Click HFSS>Excitations>Edit Impedance Mult .

The Port Impedance Multiplier dial og box appears.

2 Ent er t he value 2 i n the Impedance Multiplier box, and then c l ick

OK.

Note To edit a wave port assignment:

1. Inthe window,double-clickthenameofthewaveport

assignmentlistedintheprojecttree.

The dialogboxappears.

2. Clicktheappropriatetabs(General,Modes,PostProcessing,Defaults)

toeditanyportassignmentinformation.

3. Click toapplytheassignmentrevisions.

ZpvV V

P-------------=



Now t hat you have assigned all t he necessary boundar ies and excit at ions


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t o a model, you should review t heir speci f i c locat ions on the model in

the solver view.When you veri fy boundaries and exci t at i ons in t he solver view, youreview t he locat i ons of t he boundaries and exci tat ions as you havedefi ned t hem f or generat ing a solut ion (solving).

HFSS runs an init ial m esh and det erm ines t he locat ions of t he boundari esand exci t at i ons on the model .

Then, you can select a boundary or exci tat ion from t he l ist in t he Bound-

ary Display (Solver View) window t o v iew i t s h ighl ighted area in t hemodel .

To check the solvers view of boundaries and excitations:

1 Click HFSS>Boundary Display (Solver View).

HFSS runs an init ial mesh and determines the locations of the bound-

aries and exci tat ions on t he model.

The Solver View of Boundaries window appears, l i st ing al l t he

boundar ies andexci tat ions for t he act ive model in t he order in which t hey were

assigned.

2 Select a check box in t he Visibility column t hat corresponds wi t h t he

boundary or exc i tat ion for w hich you want t o rev iew i t s locat ion on

t he model .

The select ed boundary or exci t at i on appears in t he model in t he color

it has been assigned, as indicated in the Color column.

Visible to Solver appears in t he Solver Visibility column f or eachboundary that is val id.

Overridden appears in t he Solver Visibility column for eachboundary or exci t at i on that overwr i t es any exist ing boundary or



exci t at ion wi t h which i t over laps.

3 Veri f y t hat t he boundaries or exci t at i ons you assigned to t he model

b i di l d i t d d f l i


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are bei ng displayed as you int ended f or solvin g purposes.

4I f required, modify the parameters for those boundaries or exci ta-t ions t hat are incorrect .

5 Click Close, and t hen cl ick File>Save, or c l ick the Save a proj ect

t ool bar but t o n , t o save t he geom et r y.

You are now ready t o set up t he solut ion paramet ers for t his waveguidecombiner pr oblem and generate a solut ion.

Warning Be sure t o save geomet ri c m odels peri odicall y; HFSS does notautom ati cal ly save models. Saving frequent ly helps prevent t he lossof your wor k i f a problem occurs.


5 Generating A Solution


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Generating A Solution 5-1

5 Generating A Solution

Now t hat you have defined and veri f ied al l of t he boundaries andexci tat ions for t he waveguide combiner problem, you are ready t ogenerat e a solut ion.

Your goals for this chapter are to:

Set up t he solut ion paramet ers t hat w i l l be used in calculat ing t hesolut ion.

Val idat e t he pro j ect setup.

Generate a solut ion.

View t he solut ion dat a, such as convergence and mat r ix d atainformat ion.

Time This problem solved in approxim atel y 10 minut es on an 1.4 Ghz PC wit h1 gigabyt e of RAM. Depending on t he com put ing resources you haveavai lable, t his solut ion t ime m ay vary great ly



Before you can generat e a solut ion, you need t o specify t he solut iont Thi t l h HFSS t th t d l ti


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5-2 Generating A Solution

parameters. This controls how HFSS computes the requested solution.

Each solut ion set up includes t he fol l owing inform ati on: General dat a about t he solut ion s generat ion.

Adapt ive mesh ref inement paramet ers, i f you want t he mesh t o beref ined i terat ively in areas of highest error.

Frequency sweep param et ers, i f you want t o solve over a range offrequencies.

You can define more than one solution setup per design; however, you

wi l l def ine only onesolut ion set up for t his waveguide combiner pr oblem.

Now, you wi l l speci fy how HFSS wi l l com put e t he solut ion by adding asolut ion set up t o t he waveguide combiner design.

To add a solut ion set up t o t he design:

1 Click HFSS>Analysis Set up>Add Solut ion Setup.

The Solution Setup dialog box app ears.



The Solution Setup dialog box is div ided int o the f ol lowi ng tabs:

Includes general solution settings.


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2 Under t he General t ab, spec i fy the f o l lowing:

Includes mesh opt ions, adaptive opt ions, and solut ion

settings.

Includes advanced set t ings for ini t ial m esh generat ion andadapt ive analysis.Incl udes mesh generat ion opt ions f or modelports.

Enables you t o save the current set t ings as t he def ault s forfut ure solut ion set ups or revert t he current set t ings t o HFSSsstandard settings.



a. Enterthefollowingvalues:

SolutionFrequency

20 GHz

For e er m odal dri en sol t ion set p o m st specif


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b. Acceptallremainingdefaultsettings.

3 Accept al l d efault set t ings on the Options, Advanced, and Default

tabs.

4 Click OK.

Setup1 now app ears as a solut ion setup u nder Analysis in the pro ject

Frequency For every m odal driven solut ion set up, you must specify

t he f requency at which t o generate t he solut ion. Fort his waveguide combiner model, you wi l l solve over arange of f requencies, which wi l l requi re you to def i ne afr equency sweep in Add a Discret e Freque ncy Swe epon page 5-5. I f a f requency sweep is solved, an adapt iveanalysis is perf ormed only at t he solut ion f requency.

Maximum

Number ofPasses

9

The Maximum Number of Passes value is t he maximumnumber of mesh ref inement cycles t hat you would l ikeHFSS to perform. This value is a stopping criterion fort he adapt ive solut ion; i f t he maximum num ber of passeshas been complet ed, t he adaptive analysis st ops. I f t hemaxim um num ber of passes has not been complet ed,t he adaptive analysis wi l l cont inue unless t heconvergence cri t er ia are reached.

Maximum Delt aS Per Pass

0.001

The delt a S is t he change in t he magnit ude of t he S-paramet ers betw een t wo consecuti ve passes. The valueyou set for Maximum Delta S Per Pass is a st oppingcr i t er ion for t he adapt ive solut ion. I f t he magni tude andphase of al l S-param et ers change by an amount lesst han t h is value f rom one i terat ion to t he next , t he

adaptive analysis st ops. Ot herwi se, i t cont i nues unt i lt he request ed numb er of passes is complet ed.



t ree .


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To generat e a solut ion across a range of f reque ncies, you must add a f re-quency sweep t o t he solut ion set up. HFSS perf orms the sweep aft er t headaptive solut ion.

For t his waveguide combiner model, you wi l l add a Discretef requencysweep t o t he solut ion set up. A Discret e sweep generat es f i eld solut ionsat specif i c f requency point s in a f requency range. For t his waveguidecombiner problem , you wi l l speci f y a range of 19.5 GHz t o 20.4 GHz,

wit h a St ep Size of 0.1 GHz. The result wi l l be t en solut ions at incre-ment s of 0. 1 GHz. By default , t he f iel d solut ion is only saved for t he f inalf requency point .

Be aware t hat HFSS uses t he f ini t e elem ent mesh r ef ined during an adap-t ive solut ion at t he solut ion fr equency. I t uses t his mesh wit hout f urt herref inement . Because t he mesh for t he adapt ive solut ion is opt imi zed onlyfor t he solut ion fr equency, i t is possible t hat t he accuracy of t he result s

could vary at f requencies signi f icant ly f ar away fr om t his fr equency. I fyou wish to m inim ize the variance, you can opt t o use t he center of t hefr equency range as t he solut ion fr equency. Then, aft er inspect ing theresult s, r un addit ional adaptive passes wit h t he solut ion fr equency set t ot he cr i t ica l f requencies.

Solut ion Set upadded as a subent ryof Analysis



To add a Discret e f requency sweep t o t he solut ion set up:

1 Click HFSS>Analysis Set up>Add Sweep.

The Select dialog box app ears.


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The Select dialog box app ears.

2 Select Setup1 for t he solut ion set up for w hich t he sweep appl ies, andcl ick OK.

The Edit Sweep dialog box app ears.

3 Under t he Sweep Type section, select Discrete as t he fr equency

Sweep Type you want t o add.4 Under t he Frequency Setup sect ion, select or ent er t hese values t o



define the sweep:

Type Linear St ep

Start 19 5 GHz


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5 Clear Save Fields (All Frequencies), i f se lected.

I f se lected, t he Save Fields opt ion saves t he f i eld solut ion f or a spe-

ci f ic point . The S-paramet ers are alw ays saved for every f requency

point . The more st eps you request , t he longer i t t akes t o completethe frequency sweep.

6 Click Display t o view each of t he sweep values at t he 0.1 GHz st ep

size increment wit hin t he frequency range you specif i ed.

7 Click OK.

Sweep1 now appears as a subent ry und er Setup1 i n the proj ect t r ee.

Start 19.5 GHz

Stop 20.4 GHz

StepSize

0. 1 GHz



Befor e you run an analysis on t he waveguide combiner model, i t isimpor t ant t o f i r st perf orm a val idat i on check on t he proj ect . HFSS runs a


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check on a l l t he setup det a i ls of t he act ive pro j ect t o ver i fy t hat a l l t henecessary steps have been completed and their parameters are reason-able.

To perfor m a val idat ion check on t he proj ect wg_combiner:

1 Click HFSS>Validat ion Check.

HFSS checks t he proj ect set up, and t hen t he Validation Check win-

dow appears.

2 View t he result s of t he val idat ion check in t he Validation Check win-dow.

For t his waveguide combiner proj ect , a green check mark should

appear next t o each pro j ect st ep in t he l ist .

The fol low ing icons can appear next t o an i tem :

3 I f t he val idat ion check indicates that a st ep in your waveguide com-biner pro ject i s incomplete or incorrect , t hen return to t he st ep in

HFSS and caref ull y revi ew it s set up.

4 Click Close.

5 Click File>Save t o save any changes you m ay have made t o your

pro jec t .

Indicat es t he st ep is complet e.

Indicat es t he st ep is incomplet e.

Indicates the step may require your attent ion.

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