1-1 Patch Antenna Design Using Ansoft Designer

Patch Antenna DesignUsing Ansoft Designer

Tony Donisi

Ansoft Corporation

Introduction

OverviewSingle Patch Element DesignLinear Patch ArrayCorporate Fed Patch ArraySystem and Circuit IntegrationConclusion

Goal: To introduce a more effective and streamlined design flow for systems with patch antennas that leverage Parameterization, Solver-On-Demand and Co-Simulation

Designer Capability OverviewDesigner can accurately simulate very large structures, quickly!

SVD fastsolveLow memory requirements

Geometries can be drawn or importedUser friendly GUIDxf, iges, and popular geometry importsAnsoft Links for Allegro and other CAD tools

Full ParameterizationSolver on Demand

The ability of designer that lets the user decide which solver to use on an element by element basis

Co-SimulationThe capability of designer to seamlessly integrate circuit, system and EM simulations

Single Patch DesignDesigner allows easy design of single patches

Patch estimator tool gives a good first approximation

Fully parameterized single patch will be createdSolution for a range of geometries

Patch characteristics will be plottedFunctions of geometry, FrequencyCurrent and field distributionsPlots can be animated

Real time tuningBoth 2D and 3D plotting available

Patch Estimator ToolIntegral patch estimator tool

Single Patch: Recessed feed

WPatch

LPatch Wf1

LfeedWfeed

WSlot

LSlot

This Patch can be used as either a full planar EM model or a “Solver on

Demand” component

This Patch can be used as either a full planar EM model or a “Solver on

Demand” component Zin

)LL

(Cos)GG(2

1R slotPatch

2

121in

π±

=

2

3

0

2patch0

1 120

dSinCos

)CosWk(Sin

Gπ

θθθ

θπ

∫

=

θθθθ

θπ

π

dSin)SinLk(JCos

)CosWk(Sin120

1G 3patch00

0

2patch0

212 ∫

=

Single Patch Design ProcedureUse Patch Estimator to get starting point

10mil Duroid 5880Frequency 10GHzResulting Width and length 393 milAlso gives a starting point for Lslot

Nominal patch frequency responseLslot and Wslot will have minimal effect on center frequency

Adjust Wpatch if necessaryVary Lslot and Wslot to get Best VSWR

Assume 100ΩLslot from 10mil to 100 milWslot from 30mil to 150mil

Edge meshed to concentrate at Edges

Single Patch Frequency Sweep

Sweep of Frequency and LSlot. Note Frequency response is not centered at 10GHz

Sweep of Frequency and LSlot. Note Frequency response is not centered at 10GHz

Sweep of Frequency and Wpatch. As the frequency increases, it is obvious that LSlot will need further adjustment

Sweep of Frequency and Wpatch. As the frequency increases, it is obvious that LSlot will need further adjustment

Single Patch Optimization

Designer allows the user to optimize with respect to any variable, Including field quantities.

Single Patch Parameter ResultsSmith plot of input Match Versus Slot

width and length. Smith plot of input Match Versus Slot

width and length.

Optimal Match (100ΩΩΩΩ) at Wslot = 50milLslot=127mil

Optimal Match (100ΩΩΩΩ) at Wslot = 50milLslot=127mil

Single Patch Scalar Return Loss

Parametric sweep of return loss with respect to Wslot and Lslot Parametric sweep of return loss with respect to Wslot and Lslot

Single Patch Real Time Tuning

Single Patch Far Field & Near Field

Patch Arrays

Patches can be arranged various ArraysTwo examples will be shown

“Linear” arrayBoth x- and y- patches variable

Corporate Array

Arrays will be built with previous patches100Ω impedance

Feed networks will be consideredFeeds have impact on antenna performanceMany, many feed designs

Patch Array Feed NetworksCo-linear feed network

Straightforward Extension to other feed styles

ViasDesigner has no restrictions on viasThis presentation will not take into effect viasVias and feeds on other layers are simple to add

PatchPatch

MatchingMatching

PatchPatch

MatchingMatching

Input

Patch(100ΩΩΩΩ)Patch(100ΩΩΩΩ)

100ΩΩΩΩ Line100ΩΩΩΩ Line

Input


λλλλ/4 Transformer

λλλλ/4 Transformer 100ΩΩΩΩ Line100ΩΩΩΩ Line




Linear Array“Patch” antenna with feed

Patch dimensions as previously outlinedQuarter wave transformers

The number of patches can be largenx Set as “number of x-dimension” Patchesny Set as “number of x-dimension” Patches

Lambda4

W01

Lf1

dx

dy

Lf1

Quarter Wave transformer sections. Width and length parameterized for user optimization

Analysis OverviewOne structure can represent

CircuitPlanar EM

Circuit provides quick analysisMatch and VSWR information

Planar EM providesFieldsFull match and VSWR informationNear field and far field informationCurrent Distributions

A sample patch array is built to utilize:Solver on demandEquivalent Circuit modelingFull parameterizationParameter passing

Component DescriptionThe Patch Array will consist of:Component

Represents the overall patchContains parameters, circuit equivalent

FootprintContains geometry informationCan be scripted in VB or JavaFull script of patch can be found in appendix

SymbolSchematic representation of patch

Circuit equivalent

Design Procedure1. Determine Geometry and parameters2. Create parameterized footprint

Standard drawing of polygons or shapesVBscript or JavaScript

3. Create circuit equivalent4. Create symbol5. Generate component6. Optional: Create circuit equivalent

Once this is done the user has a flexible “Solver on Demand” component that can be used as a versatile “stand alone” design or as part of a larger scale circuit or system design.

Once this is done the user has a flexible “Solver on Demand” component that can be used as a versatile “stand alone” design or as part of a larger scale circuit or system design.

Patch Array DesignOne row, nx = 4 (4 elements) nominalSame “patch” as previously designed

10mil, ε2.2 RT Duroid50Ω, 8 mil, 70.7Ω, 17mil, 50Ω, 30milContains parameters, circuit equivalentλ/4 = 218 mil

The spacing between elements is important“Orthogonal” pattern

Normal to x-y planePatch elements must be fed in phase

Feeding the patches in phase will make the pattern orthogonal to the x-y plane. This will occur when the

separation is an integral multiple of a

wavelength

Performance Plots

Gain Vs dxGain Vs dx

Return LossReturn Loss

N=4, dx= 600mil Nominal

N=4, dx= 600mil Nominal

Swept Plots

Effect of varying “dx” versus frequency Effect of varying “dx” versus frequency

Effect of varying “dx” on the 3D gain pattern, from 500mil to 1200mil. The optimal gain/direction occurs between 800mil and 100mil

Effect of varying “dx” on the 3D gain pattern, from 500mil to 1200mil. The optimal gain/direction occurs between 800mil and 100mil

4-Element Phased ArrayPreviously designed recessed patch

Array of 4 elementsFully parameterized

Input Phase and amplitude can be set to variablesThese can be modified to observe field patterns

Designer allows the user to feed the ports with different phases and amplitudes. These can be set to variables to allow for any desired feed pattern

Designer allows the user to feed the ports with different phases and amplitudes. These can be set to variables to allow for any desired feed pattern

Small Phased Array Animation

Variables are set up for the four ports. In this simple example, the ports toggle between 0 and 135 in a set pattern, based on the variable FeedControl.

Corporate Fed ArrayA “corporate” array is a popular configurationFeed structure can affect performanceMethods of analysis

Infinite arrayFinite array without feedFinite array with feed

Corporate Feed Patch GeometryAssume 4-Unit CellRecessed Slot PatchPatch dimensions

Calculated previously

Variable number of patches

dx

dy

Wpatch

W100

Lf1

(0,0)

LSlot

WSlot

Corporate Array Dimensions

Fully Parameterized2n Unit Cells

Square Array

Single Feed PointPatch may be any dimensionVBScript Generation

Patch Geometry

Quarter Wave transformer sections. Width and length parameterized for user optimization

This patch was created with a VB script, located in appendix

Corporate Fed 8X8 Array

Solution Details21,267 Unknowns343M Ram

13 Minutes

Corporate Fed 8X8 Array Details

Solution Plots

Corporate Fed 16X16 Array

Solution Details86,428 Unknowns121M Ram2 Hours, 54 Minutes

Corporate Fed 16X16 Solutions

Patch as an Infinite array

System Co-simulation

Circuit, System and EM Cosimulation

ConclusionAn improved design flow for systems with patch antennas has been presentedAdvanced features

ParameterizationSolver On DemandCo-Simulation

OptimizationGraphics and plottingField and geometry plots and animationsIntegration with system and circuit tool

Appendix: Patch Arrays

Patches can be arranged various ArraysTwo examples will be shown

“Linear” arrayBoth x- and y- patches variable

Corporate Array

Arrays will be built with previous patches100Ω impedance

Appendix: Linear Array“Patch” antenna with feed

The “wide” sections are “patches”, narrow sections are the feedsThe lengths of the patches are equalThe lengths of the feeds are equal

The widths of the patches can vary to form a “beam”The number of patches can be large

Up to 16 patches

Lpatch

dx

WfeedW01

W03

Wn

Patch “n”

W02

Appendix: Design Procedure1. Determine Geometry and parameters2. Create parameterized footprint3. Create circuit equivalent4. Create symbol5. Generate component

Once this is done the user has a flexible “Solver on Demand”component that can be used as a versatile “stand alone” design or as part of a larger scale circuit or system design.

Once this is done the user has a flexible “Solver on Demand”component that can be used as a versatile “stand alone” design or as part of a larger scale circuit or system design.

Appendix: Important Linear Patch ParametersA component can be set up with the following parameters:

LpatchW1 to W16WFeeddxn

These parameters fully define the patch element

Appendix: Component Description

The Linear Patch will consist of:Component

Represents the overall patchContains parameters, circuit equivalent

FootprintContains geometry informationCan be scripted in VB or Java

SymbolSchematic representation of patch

Appendix: Determine Footprint Geometry Variables

Lpatch

Lfeed = dx-Lpatch

Since “rectangle” objects are determined by their center, width and height, the centers of each of the patches/feeds will be determined.

Center “x” Point ChartA Reference, (0,0)B Lfeed/2+Lpatch/2C Lfeed+LpatchD (3/2)*Lfeed+(3/2)*LpatchE 2*Lfeed+2*LpatchF (5/2)*Lfeed+(5/2)*Lpatch

Y (n-.5)*(Lfeed+Lpatch)Z n*(Lfeed+Lpatch)

A

B C D E F Y Z

dx

Appendix: Creating a Footprint

dx

Appendix: Create Footprint Script Part 1The script is broken into two parts for clarityThe first part sets up variablesThe second part is the actual codeNote that the code section is only a few lines

One loop

Width(6) = LayoutHost.Pars.Item("W06")Width(7) = LayoutHost.Pars.Item("W07")Width(8) = LayoutHost.Pars.Item("W08")Width(9) = LayoutHost.Pars.Item("W09")Width(10) = LayoutHost.Pars.Item("W10")Width(11) = LayoutHost.Pars.Item("W11")Width(12) = LayoutHost.Pars.Item("W12")Width(13) = LayoutHost.Pars.Item("W13")Width(14) = LayoutHost.Pars.Item("W14")Width(15) = LayoutHost.Pars.Item("W15")Width(16) = LayoutHost.Pars.Item("W16")Lfeed = LayoutHost.LayoutPars.Item("Lfeed")idnum = LayoutHost.GetLayerID("anywhere")

‘Script Part 1 Defining all VariablesDim W1, W2, W3, W4, W5, W6, W7, W8Dim W9, W10, W11, W12, W13, W14, W15, W16Dim Lpatch, Lfeed, idnum, x, n, pi, pointsvar, width(20)set Pointsvar = LayoutHost.CreatePointsObject()pi = 3.1415926535n = LayoutHost.Pars.Item("n")Lpatch = LayoutHost.Pars.Item("Lpatch")Wfeed = LayoutHost.Pars.Item("Wfeed")dx= LayoutHost.Pars.Item("dx")

Width(1) = LayoutHost.Pars.Item("W01")Width(2) = LayoutHost.Pars.Item("W02")Width(3) = LayoutHost.Pars.Item("W03")Width(4) = LayoutHost.Pars.Item("W04")Width(5) = LayoutHost.Pars.Item("W05")

Appendix: Create Footprint Script part 2‘Main VB Script Just a for/ Next Loop with incremental Parameters!

‘Create a “Points” object to Draw First line pointsvar.Add (-1*lfeed/2),(width(1))pointsvar.Add (n*(Lpatch+Lfeed)+lfeed/2),(Width(1))‘Draw First line layouthost.NewRect idnum, 0, 0, Lfeed,Wfeed, 0

‘Main Loopfor x = 1 to n

‘Draw Patcheslayouthost.NewRect idnum, (x-.5)*(Lpatch+Lfeed),0, Lpatch,width(x),0

‘Draw Feedslayouthost.NewRect idnum, (x)*(Lpatch+Lfeed),0, Lfeed,Wfeed,0

next

‘Manipulat PortsLayoutHost.MovePort "n1", -1*lfeed/2,0, piLayoutHost.MovePort "n2", n*(Lpatch+Lfeed)+lfeed/2,0, 0

‘Main VB Script Just a for/ Next Loop with incremental Parameters!

‘Create a “Points” object to Draw First line pointsvar.Add (-1*lfeed/2),(width(1))pointsvar.Add (n*(Lpatch+Lfeed)+lfeed/2),(Width(1))‘Draw First line layouthost.NewRect idnum, 0, 0, Lfeed,Wfeed, 0

‘Main Loopfor x = 1 to n

‘Draw Patcheslayouthost.NewRect idnum, (x-.5)*(Lpatch+Lfeed),0, Lpatch,width(x),0

‘Draw Feedslayouthost.NewRect idnum, (x)*(Lpatch+Lfeed),0, Lfeed,Wfeed,0

next

‘Manipulat PortsLayoutHost.MovePort "n1", -1*lfeed/2,0, piLayoutHost.MovePort "n2", n*(Lpatch+Lfeed)+lfeed/2,0, 0

Appendix: Create Circuit Equivalent

A simple circuit equivalent could be madeElectromagnetic simulation is very fast

Largest problemsSVD Fast SolveLow memory requirements

Geometries may get very largeCircuit equivalent is a good method to speed solutionGives S-parameter equivalentsDemonstrates Designer’s flexibility

Appendix: Equivalent Circuit

Purely optionalSome designers prefer electromagnetic analysis only

May consist of any circuit elementCan be as simple as a single resistorCan be as complex as user can describeIs formed as a “Netist” line

Appendix: Netlist BasicsTo complete the component, a Netlist line will be added

Circuit simulations run much faster than Planar EM simulationsIt is desirable to have a circuit equivalent even if its just an approximation

Designer is a “Netlist” based programAll simulations run the engine through a netlistThis netlist is Spice compatible where applicable

The circuit geometry is similar to 3 to 33 “microstrip”transmission lines

Transmission lines are well characterized within the circuit solverBetween each transmission line, there may be a “step discontinuity”

The “circuit equivalent would look like:

Appendix: Geometric Variable SetupThe “largest” structure (n=16) contains

16 patches and 17 Feeds : Total 33 Transmission linesOne “step discontinuity between each lineTotal 32 Steps

The smallest Structure (n=1) contains:1 patch, 2 feed lines, and 3 steps

Provisions must be made in the netlist to “remove” components that are not used

Accomplished by setting “lengths” of the unused lines to Lpatch/1000“Widths” of the Unused transmission lines set to Wfeed“Unused” transitions take care of themselves

“Worst case” (n=1) Total of 30 lines “hanging” off end of the model Total length of Lpatch *30/1000This is an insignificant amount

Appendix: Geometric Variable SetupVariables We1 through we33 represent widths of each lineThe “odd” numbers represent feeds

They will all have the width “wfeed”The “even” numbers of Wexx represent patch widths

Dependent on the number of sections 16 sections, possibly 16 different width values

Case 1: n = 1Second line (first patch) set to width We1Remaining sections set to a width of WfeedLengths are set to Lpatch/1000

Case 2: 1 < n <16sections after the nth section are set to width WfeedTherefore Transmission line 2 (first patch) will always be set to We1

Lengths of the lines will be defined as L1 through L33Depending on the value of n, these transmission lines will be set to a length corresponding to the length of the patches & feeds, or set to a small value, Lpatch/1000 as discussed

“If” statements will be used to define the lengths and widths

Appendix: Typical Variable Property

We32@id= \ if \( @n < 16 , @wfeed , @w16 \) \

The variable We32

The variable We32@id (no space) is the syntax that tells designer to assign a unique identifier to the variable We32

Open and closed brackets surround an expression in the netlist. Designer uses brackets for special functions, so In order to netlist correctly, the backslash character must be put in front of the bracket or any other special character, such as parenthesis. This tells designer to netlist this character directly.

The @ character preceding a variable name means that the variable is a “passed parameter” directly from the component

The if statement in the netlist line will have the syntax If (expression, true, false) or We32= if(n<16, wfeed, w16)

Appendix: Component SetupShown are the lines in the component and the netlist line

In the component, carriage returns are for visuals in this presentation, they will not be in the component. The \n tells Designer to put carriage returns in the netlistDesigner puts the carriage returns in the netlist

MSTRL:@ID %0 %_101 w= @Wfeed p= \ @dx - @Lpatch \ Sub=@sub \n MSSTEP:@ID_ca %_101 %_1 W1= @Wfeed W2= @W01 sub=@sub \n

61 more “lines”MSSTEP:@ID_bf %_132 %_32 W1= \ We32@id \ W2= @wfeed sub=@sub \nMSTRL:@ID_af %_32 %1 w=@Wfeed p= \ @dx - @Lpatch \ Sub=@sub

The syntax for “defined” variables is different that that of the passed parameters. We32 was defined previously, and as explained, Designer assigned a unique ID to it. To reference that variable in the netlist line, @id must follow the variable name

MSTRL:1 Port1 inet_101 w= 10mil p= 150mil - 50mil Sub=Alumina MSSTEP: inet_101 inet_1 W1= 10mil W2= 50mil sub=Alumina

62 more “lines”

MSSTEP: inet_132 inet_32 W1= We321 W2= 10mil sub=AluminaMSTRL: inet_32 Port2 w=10mil p= 150mil - 50mil Sub=Alumina

Component text. Note that there will be no

carriage returns.

Component text. Note that there will be no

carriage returns.

Netlist Line. Note that Designer puts in carriage returns.

Netlist Line. Note that Designer puts in carriage returns.

Since it is a “multiple line” component, each component must have a unique ID. The underscore following the @ID tells designer to assign it a unique ID, and each element must have unique characters following the underscore. These can be alpha-numeric

Appendix Linear Patch ScriptDim Lpatch, Lfeed, idnum, x, n, pi, pointsvar,feedline1,feedline2,feedline3Dim width(20)

Set Pointsvar = LayoutHost.CreatePointsObject()Set Feedline1= LayoutHost.CreatePointsObject()Set Feedline2= LayoutHost.CreatePointsObject()Set Feedline3= LayoutHost.CreatePointsObject()Set PatchOutline=LayoutHost.CreatePointsObject()

pi = 3.1415926535nx = LayoutHost.Pars.Item("nx")ny = LayoutHost.Pars.Item("ny")n = LayoutHost.Pars.Item("n")Lpatch = LayoutHost.Pars.Item("Lpatch")Wfeed = LayoutHost.Pars.Item("Wfeed")dx= LayoutHost.Pars.Item("dx")dy= LayoutHost.Pars.Item("dy")lf1= LayoutHost.Pars.Item("lf1")lf2= LayoutHost.Pars.Item("lf2")wf1= LayoutHost.Pars.Item("wf1")wf2= LayoutHost.Pars.Item("wf2")W100= LayoutHost.Pars.Item("W100")W50= LayoutHost.Pars.Item("W50")W70= LayoutHost.Pars.Item("W70")Lambda4= LayoutHost.Pars.Item("Lambda4")Wcutout= LayoutHost.Pars.Item("WSlot")Lcutout= LayoutHost.Pars.Item("LSlot")WPatch= LayoutHost.Pars.Item("WPatch")Linput= LayoutHost.Pars.Item("Linput")

Lfeed = LayoutHost.LayoutPars.Item("Lfeed")idnum = LayoutHost.GetLayerID("anywhere"), W50

if x=nx-2 thenFeedline2.Add (cx+dx-w100/2-lambda4),(cy-lf1)Feedline2.Add (cx+dx+w100/2),(cy-lf1)LayoutHost.NewLine FeedL, feedline2,W100, "corner", "flat"call clearlinesend ifend Sub 'Draw patch

for y = 0 to ny-1'*****Draw Vertical FeedsFeedline2.Add (-1*lambda4-w100),(y*dy-lf1+(w70-w100)/2)Feedline2.Add (w100/2),(y*dy-lf1+(w70-w100)/2)LayoutHost.NewLine Qwave, feedline2,W70, "corner", "flat"Feedline2.Add (-1*lambda4-w100),(y*dy-lf1)Feedline2.Add (-1*lambda4-w100-lf2),(y*dy-lf1)LayoutHost.NewLine FeedL, feedline2,W100, "corner", "flat"

if y<>0 thenFeedline2.Add (-1*lambda4-w100-lf2+w70/2),(y*dy-lambda4-lf1-w100/2)Feedline2.Add (-1*lambda4-w100-lf2+w70/2),(y*dy-lf1-w100/2)LayoutHost.NewLine Qwave, feedline2,W70, "corner", "flat"call clearlines

Feedline2.Add (-1*lambda4-w100-lf2+w100/2),(y*dy-lambda4-lf1-w100/2)Feedline2.Add (-1*lambda4-w100-lf2+w100/2),((y-1)*dy-lf1+w100/2)LayoutHost.NewLine FeedL, feedline2,W100, "corner", "flat"end if

for x = 0 to nx-1Call drawpatch(dx*x,dy*y)

next ‘nxNext 'ny'***Draw input FeedFeedline2.Add (-1*lambda4-w100-lf2+w100/2)-w100/2,(-lf1-w100/2+w50/2)Feedline2.Add (-1*lambda4-w100-lf2+w100/2)-linput-w100/2,(-lf1-w100/2+w50/2)LayoutHost.NewLine idnum, feedline2,W50, "corner", "flat"call clearlines' Manipulate PortLayoutHost.MovePort "n1", (-1*lambda4-w100-lf2+w100/2)-linput-w100/2,(-lf1-w100/2+w50/2), piLayoutHost.SetPortWidth idnum, "n1", W50

Sub ClearLines'This routine will clear all feedlines and is to be used after each line build…..End Sub ' Clearlines

Sub DrawPatch(CenterZX,CenterZY)Cx =CenterZXCy =CenterZy

'Patch Drawing Subroutine, Cx and Cy are the coordsPatchOutline.Add (cx-Wpatch/2),(cy)PatchOutline.Add (cx-Wpatch/2),(cy+Lpatch)PatchOutline.Add (cx+Wpatch/2),(cy+Lpatch)PatchOutline.Add (cx+Wpatch/2),(cy)PatchOutline.Add (cx+WCutout/2),(cy)PatchOutline.Add (cx+WCutout/2),(cy+Lcutout)PatchOutline.Add (cx+W100/2),(cy+Lcutout)PatchOutline.Add (cx+W100/2),(cy)PatchOutline.Add (cx-W100/2),(cy)PatchOutline.Add (cx-W100/2),(cy+Lcutout)PatchOutline.Add (cx-Wcutout/2),(cy+Lcutout)PatchOutline.Add (cx-Wcutout/2),(cy)LayoutHost.Newpoly idnum, Patchoutline

'*** Draw Horiz Feeds'LayoutHost.NewCircle idnum,cx,cy,(Wpatch/4)Feedline2.Add (cx),(cy)Feedline2.Add (cx),(cy-lf1)

if x<>nx-1 thenFeedline2.Add (cx+dx-w100/2-lambda4),(cy-lf1)end ifLayoutHost.NewLine FeedL, feedline2,W100, "corner", "flat"

1-1 Patch Antenna Design Using Ansoft Designer

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