pcbStack

R2026b

Single feed or multi-feed PCB antenna

Description

The pcbStack object is a single-feed or multi-feed printed circuit board (PCB) antenna. Use the pcbStack object:

• To create single-layer, multilayer metal, or metal-dielectric substrate antennas.

• To create an arbitrary number of feeds and vias in an antenna.

• To create a PCB antenna from antenna and array catalog elements.

Note

To generate a Gerber file, include a substrate layer. Use the Substrate property to create this layer in the PCB antenna. For more information, see Convert Circular Microstrip Patch into PCB Antenna.

Creation

Syntax

pcbant = pcbStack

pcbant = pcbStack(PropertyName=Value)

pcbant = pcbStack(ant)

Description

pcbant = pcbStack creates an air-filled single-feed PCB with two metal layers.

pcbant = pcbStack(PropertyName=Value) sets properties using one or more name-value arguments. PropertyName is the property name and Value is the corresponding value. For example, pcbStack(FeedDiameter=2e-04) creates a PCB antenna with a feed diameter of 0.2 mm. You can specify several name-value arguments in any order as PropertyName1=Value1,...,PropertyNameN=ValueN. Properties that you do not specify retain their default values.

pcbant = pcbStack(ant) converts any 2-D or 2.5-D antenna from the antenna catalog into a PCB antenna for modeling and analysis. You can also convert antenna array objects from the antenna array catalog to a PCB antenna. For a list of supported catalog elements, see Supported Catalog Elements.

Properties

Name — Name of PCB antenna

"MyPCB" (default) | string

Name of PCB antenna, specified as a string.

Example: "PCBPatch"

Data Types: string

Revision — Revision details of PCB antenna design

"1.0" (default) | string

Revision details of PCB antenna design, specified as a string.

Example: "2.0"

Data Types: string

BoardShape — Shape of PCB board

antenna.Rectangle object (default) | shape object

Shape of the PCB board, specified as one of the following shape objects:

• antenna.Rectangle object.

• antenna.Circle object.

• antenna.Ellipse object.

• antenna.Polygon object.

• antenna.Triangle object.

Example: antenna.Polygon

BoardThickness — Thickness of PCB board

0.0100 (default) | positive scalar

Thickness of the PCB board, specified as a positive scalar. The value of this property is the sum of the thicknesses of all the dielectric layers that lie below the top metal layer. The object treats dielectric layers that are above the top metal layer as coating. Set this property before you set the Layers property. For more information on BoardThickness, see Board Thickness versus Dielectric Thickness in PCB.

Example: 0.02000

Data Types: double

Layers — Metal and dielectric layers

{[1×1 antenna.Rectangle] [1×1 antenna.Rectangle]} (default) | cell array of metal layer shapes and dielectric

Metal and dielectric layers, specified as a cell array of metal layer shapes and dielectric. You can specify one metal shape or one dielectric per layer starting with the top layer and proceeding down.

Data Types: cell

FeedFormat — Input format for feed setup

"FeedLocations" (default) | "FeedDefinitions"

Input format for the feed setup, specified as one of the following:

• "FeedLocations" — Use the FeedLocations property to configure the feeds based on the specified locations.

• "FeedDefinitions" — Use the FeedDefinitions property to configure the feeds that are too complex to be inferred from the feed locations.

Example: "FeedDefinitions"

Data Types: string

FeedLocations — Cartesian coordinates of feed points for PCB antenna

[-0.0187 0 1 2] (default) | N -by-3 or N-by-4 array

Cartesian coordinates of feed points for the PCB antenna, specified as either N -by-3 array for a balanced feed or N-by-4 array for an unbalanced feed. You can place the feed/feeds inside the board or at the edge of the board. The arrays translate to the following:

• N -by-3 – [x, y, Layer]

• N-by-4 – [x, y, SigLayer, GndLayer]

  For more information about location-based feeds, see Feed Model.

Example: [-0.0187 0 1 2]

Data Types: double

FeedDefinitions — Type of feed

ArbitraryFiniteGapFeed object | CoaxialFeed object | DeltaGapFeed object | EdgeFeed object | FiniteGapFeed object | ProbeFeed object

Type of feed, specified as one of the values in the table:

Feed Type	Description	Applications
ArbitraryFiniteGapFeed	Defines a lumped feed across arbitrarily shaped finite gaps between multiple metal regions, enabling you to specify potential relationships among the conductors	Coplanar-Waveguide (CPW)-fed monopole and slot antennas Multi-ground antenna feeds Differential MIMO antenna feeds Complex multi-port PCB antenna structures with multiple signal and ground conductors
ProbeFeed	Models a vertical conductive pin or via that excites the PCB by connecting a signal layer to a reference ground	Probe-fed microstrip patch antennas, stacked patch antennas, planar Inverted-F antenna (PIFA) structures Antennas where the feed is brought from the ground plane through a via to the radiator
EdgeFeed	Excites the structure from the edge of the PCB, typically representing a microstrip or stripline launch	Inset-fed microstrip patch antennas, edge-fed rectangular and circular patch antennas PCB trace antennas fed directly from a microstrip line Vivaldi and tapered-slot antennas where excitation originates at the PCB edge
DeltaGapFeed	Applies an idealized lumped excitation across an infinitesimally small gap between two conductors	Dipole PCB antennas Bow-tie antennas Folded dipoles Slot antennas excited across a narrow feed gap General balanced PCB radiator structures
CoaxialFeed	Models a coaxial-style feed as a signal via excited across an annular antipad gap in a ground metal layer (higher-fidelity version of a probe feed)	High-fidelity modeling of probe-fed patch antennas SMA-fed patch antennas Via-fed PCB antennas requiring accurate feed parasitics Correlation of simulation with measured coax-fed prototypes
FiniteGapFeed	Represents a lumped excitation across a physically finite gap between conductors for improved realism over delta‑gap feeds	Slot antennas with finite-width excitation Aperture-coupled patch antennas (feed aperture region) Internal antenna ports in PCB antenna structures Differentially excited PCB radiators requiring physical feed width representation

Example: DeltaGapFeed

Dependencies

To enable the FeedDefinitions property, set the FeedFormat property to "FeedDefinitions".

FeedDiameter — Center pin diameter of feed connector

1.0000e-03 (default) | positive scalar in meters

Center pin diameter of the feed connector, specified as a positive scalar in meters.

Example: 2.000e-04

Data Types: double

ViaLocations — Cartesian coordinates of electrical shorts

M-by-4 array

Cartesian coordinates of electrical shorts, specified as a M-by-4 array. The array translates to the following:

• M-by-4 – [x, y, SigLayer, GndLayer]

Example: [0 -0.025 1 2]

Data Types: double

ViaDiameter — Electrical shorting pin diameter between metal layers

positive scalar | positive vector

Electrical shorting pin diameter between metal layers, specified as a positive scalar in meters for a single pin or a positive vector in meters for multiple pins. The number of values specified in this property must match the number of pins.

Example: 1.0e-3

Data Types: double

FeedViaModel — Model for approximating feed and via

"strip" (default) | "square" | "hexagon" | "octagon"

Model for approximating feed and via, specified as one of the following:

• strip – A rectangular strip approximation to the feed or via cylinder. This approximation is the simplest and results in a small mesh.

• square – A 4-sided polyhedron approximation to the feed or via cylinder.

• hexagon – A 6-sided polyhedron approximation to the feed or via cylinder.

• octagon – An 8-sided polyhedron approximation to the feed or via cylinder.

Example: "octagon"

Data Types: string

FeedVoltage — Excitation voltage applied at each feed point

1 (default) | positive scalar in volts | positive 1-by-N array in volts

Excitation voltage applied at each feed point, specified as a positive scalar in volts for a single feed point or a positive 1-by-N array for N feed points. The default excitation voltage is 1V.

Example: 2

Data Types: double

FeedPhase — Excitation phase at each feed point

0 (default) | real scalar in degrees | real 1-by-N vector in degrees

Excitation phase at each feed point, specified as a real scalar in degrees for a single feed point or a real 1-by-N vector in degrees for N feed points. The default excitation phase is 0 degrees.

Example: 2

Data Types: double

Conductor — Type of metal material

metal("PEC") (default) | metal object

Type of the metal used as a conductor, specified as a metal object. You can select any metal from the MetalCatalog or specify a metal of your choice. For more information on metal conductor meshing, see Meshing.

Example: metal("Copper")

Tilt — Tilt angle of antenna

0 (default) | scalar | vector

Tilt angle of the antenna in degrees, specified as a scalar or vector. For more information, see Rotate Antennas and Arrays.

Example: 90

Example: Tilt=[90 90],TiltAxis=[0 1 0;0 1 1] tilts the antenna at 90 degrees about the two axes defined by the vectors.

Data Types: double

TiltAxis — Tilt axis of antenna

[1 0 0] (default) | three-element vector | 2-by-3 matrix | "X" | "Y" | "Z"

Tilt axis of the antenna, specified as one of these values:

• Three-element vector of Cartesian coordinates in meters. In this case, each coordinate in the vector starts at the origin and lies along the specified points on the x-, y-, and z-axes.

• Two points in space, specified as a 2-by-3 matrix corresponding to two three-element vectors of Cartesian coordinates. In this case, the antenna rotates around the line joining the two points.

• "x", "y", or "z" to describe a rotation about the x-, y-, or z-axis, respectively.

For more information, see Rotate Antennas and Arrays.

Example: [0 1 0]

Example: [0 0 0;0 1 0]

Example: "Z"

Data Types: double | string

Load — Lumped elements

[1x1 lumpedElement] (default) | lumpedElement object

Lumped elements added to the antenna feed, specified as a lumpedElement object. You can add a load anywhere on the surface of the antenna. By default, the load is at the feed.

Example: lumpedElement(Impedance=75)

SolverType — Type of solver used for analysis

"MoM" (default) | "FEM"

Type of solver used for analysis, specified as "MoM" or "FEM". The default solver is method of moments ("MoM"). For more information on the MoM solver, see Method of Moments Solver for Metal and Dielectric Structures. To use the finite element method ("FEM") solver, you need an RF PCB Toolbox™ license and the Integro-Differential Modeling Framework for MATLAB add-on. For more information on the FEM solver and the required add-on installation, see FEM-based Solver for RF Structures (RF PCB Toolbox). To access FEM solver settings, use the solver object.

• FEM solver supports only pattern, peakRadiation, and sparameters analyses of the pcbStack object.

• For the FEM solver, the following constraints apply:

  • FeedVoltage is fixed at 1 V

  • FeedPhase is fixed at 0 degrees

  • Load is not supported

  • Only Metal of type PEC is supported

  • Tilt is fixed at 0 degrees

• For pattern analysis with the FEM solver, the following constraints apply:

  • Polarization is not supported

  • Type as Phase is not supported

  • Termination is fixed at 50 ohms

  • CoordinateSystem of type UV is not supported

Example: "FEM"

Data Types: string

Connector — Type of RF connector

RFConnector object

Type of RF connector assembled at the feed locations, specified as an RFConnector (RF PCB Toolbox) object. Specify this property when SolverType is set to "FEM".

Object Functions

array	Create array of PCB stack objects
axialRatio	Calculate and plot axial ratio of antenna or array
bandwidth	Calculate and plot absolute bandwidth of antenna or array
beamwidth	Beamwidth of antenna
charge	Charge distribution on antenna or array surface
correlation	Correlation coefficient between two antennas in array
current	Current distribution on antenna or array surface
efficiency	Calculate and plot radiation efficiency of antenna or array
EHfields	Electric and magnetic fields of antennas or embedded electric and magnetic fields of antenna element in arrays
feedCurrent	Calculate current at feed for antenna or array
gerberWrite	Generate Gerber files
impedance	Calculate and plot input impedance of antenna or scan impedance of array
info	Display information about antenna, array, or platform
layout	Display array or PCB stack layout
memoryEstimate	Estimate memory required to solve antenna or array mesh
mesh	Generate and view mesh for antennas, arrays, and custom shapes
meshconfig	Change meshing mode of antenna, array, custom antenna, custom array, or custom geometry
msiwrite	Write antenna or array analysis data to MSI planet file
pattern	Plot radiation pattern of antenna, array, or embedded element of array
patternAzimuth	Azimuth plane radiation pattern of antenna or array
patternElevation	Elevation plane radiation pattern of antenna or array
peakRadiation	Calculate and mark maximum radiation points of antenna or array on radiation pattern
phaseShift	Calculate phase shift values for arrays or multi-feed PCB stack
rcs	Calculate and plot monostatic and bistatic radar cross section (RCS) of platform, antenna, or array
resonantFrequency	Calculate and plot resonant frequency of antenna
returnLoss	Calculate and plot return loss of antenna or scan return loss of array
show	Display antenna, array, AI-based antenna, platform, or shape
sparameters	S-parameters for antenna or array
stlwrite	Write mesh information to STL file
vswr	Calculate and plot voltage standing wave ratio (VSWR) of antenna or array element

Examples

End Loaded Planar Dipole

Setup parameters.

vp = physconst("lightspeed");
f = 850e6;
lambda = vp./f;

Build a planar dipole with capacitive loading at the ends.

L = 0.15;
W = 1.5*L;
stripL = L;
gapx = 0.015;
gapy = 0.01;
r1 = antenna.Rectangle(Center=[0 0], Length=L, Width=W, Center=[lambda*0.35 0]);
r2 = antenna.Rectangle(Center=[0 0], Length=L, Width=W, Center=[-lambda*0.35 0]);
r3 = antenna.Rectangle(Length=0.5*lambda, Width=0.02*lambda, NumPoints=2);
s = r1 + r2 + r3;
figure
show(s)

Assign the radiator shape to pcbStack and make the changes to the board shape and feed diameter properties.

boardShape = antenna.Rectangle(Length=0.6, Width=0.3);
p = pcbStack;
p.BoardShape = boardShape;
p.Layers = {s};
p.FeedDiameter = 0.02*lambda/2;
p.FeedLocations = [0 0 1];
figure
show(p)

Analyze the impedance of the antenna. Effect of the end-loading should result in the series resonance to be pushed lower in the band.

figure
impedance(p,linspace(200e6,1e9,51))

PCB Stack of Dielectric Antenna

Create a pcb stack antenna with 2 mm dielectric thickness at the radiator and air below it. Display the structure.

p = pcbStack;
d1 = dielectric("FR4");
d1.Thickness = 2e-3;
d2 = dielectric("Air");
d2.Thickness = 8e-3;
p.Layers = {p.Layers{1},d1,d2,p.Layers{2}};
p.FeedLocations(3:4) = [1 4];
show(p)

Directivity Pattern of PCB Stack Antenna

Create a PCB stack antenna from reflector backed bowtie.

b = design(bowtieRounded,1e9);
b.Tilt = 90

b = 
  bowtieRounded with properties:

        Length: 0.0959
    FlareAngle: 90
     Conductor: [1×1 metal]
          Tilt: 90
      TiltAxis: [1 0 0]
          Load: [1×1 lumpedElement]

b.TiltAxis = [0 1 0];
r = reflector(Exciter=b);
p = pcbStack(r);

Plot the directivity pattern of the antenna at 1 GHz.

pattern(p,1e9);

Create PCB Antenna From Antenna Library Element

Create a coplanar inverted F antenna.

fco = invertedFcoplanar(Height=14e-3, GroundPlaneLength=100e-3,...
                  GroundPlaneWidth=100e-3);

Use this antenna to create a pcbStack object.

p = pcbStack(fco);

Convert Circular Microstrip Patch into PCB Antenna

Create a circular microstrip patch.

p = patchMicrostripCircular;
d = dielectric;
d.EpsilonR = 4.4;
p.Radius = 0.0256;
p.Height = 1.6e-3;
p.Substrate = d;
p.GroundPlaneLength = 3*0.0256;
p.GroundPlaneWidth = 3*0.0256;
p.FeedOffset = [0.0116 0];

Create a PCB of this patch using pcbStack.

pb = pcbStack(p);
pb.FeedDiameter = 1.27e-3;
pb.ViaLocations = [0 pb.FeedLocations(1)/1.1 1 3];
pb.ViaDiameter = pb.FeedDiameter;
figure
show(pb)

Define the RF SMA connector and use it with the GerbLook writer service to generate Gerber files of the design.

C = SMA_Jack_Cinch;
O = PCBServices.GerbLookWriter;               
O.DefaultViaDiam = pb.ViaDiameter;
O.Filename = 'Microstrip circular patch-9a';
Am = PCBWriter(pb,O,C);
gerberWrite(Am)

Generated File: 'C:\Users\user\OneDrive - MathWorks\Documents\MATLAB\ExampleManager\user.Bdoc.DocWork1\antenna-ex88881296\MicrostripCircularPatch_9a.zip'
'(name is available in system cut-buffer)

13 files in PCB stack
   Size Lines File
     1k    36 MicrostripCircularPatch_9a.gtl (Copper,L1,Top,Signal)
     1k    69 MicrostripCircularPatch_9a.gbl (Copper,L2,Bot,Signal)
   107b     5 MicrostripCircularPatch_9a_1-3.txt (ExcellonPlated,1,3)
    98b     9 MicrostripCircularPatch_9a.gts (Soldermask,Top)
   227b    18 MicrostripCircularPatch_9a.gbs (Soldermask,Bot)
   103b     5 MicrostripCircularPatch_9a.txt (ExcellonPlated,1,2)
   505b    42 MicrostripCircularPatch_9a.gbp (Paste,Bot)
   130k  6817 MicrostripCircularPatch_9a.gbo (Legend,Bot)
   180k  9068 MicrostripCircularPatch_9a.gto (Legend,Top)
     1k    39 MicrostripCircularPatch_9a.gpi (PhotoplotterInfo,Info)
     1k    36 MicrostripCircularPatch_9a.dri (DrillStationInfo,Info)
     1k    22 MicrostripCircularPatch_9a.ipc (IPCD356A,Info)
              MicrostripCircularPatch_9a.gml (Profile,NP)

If you have internet connection, the Gerber files generation process opens GerbLook viewer in the web browser window. Drag and drop the Gerber files into the browser window. The viewer renders the PCB design.

This is the top view of the PCB.

This is the bottom view of the PCB.

Create PCB Antenna Using Antenna Array Library Element

Create a coplanar inverted-F antenna.

fco = invertedFcoplanar(Height=14e-3, GroundPlaneLength=100e-3,...
                   GroundPlaneWidth=100e-3);
show(fco)

Create a linear array with inverted-F antenna as its elements.

la = linearArray;
la.Element = fco;
la.NumElements = 4;
show(la)

Use this antenna array to create the PCB antenna.

p = pcbStack(la);
show(p)

Create PCB Antenna Using Linear Dipole Array and Dipole Antenna Element

Create a dipole antenna object and linearArray antenna array object. In the linearArray antenna object, leave the Element property set to its default value of dipole. Set the ElementSpacing property to 4."

d1 = dipole;
d2 = linearArray(ElementSpacing=4);

To set the Z-coordinate of pcbStack antenna object to zero, rotate the dipole and linear dipole array around 90 degrees using the Tilt property. Then set the TiltAxis property to [ 0 -1 0 ] for dipole and linear dipole array antennas.

d1.Tilt = 90;
d2.Element.Tilt = 90;
d1.TiltAxis = [0 -1 0];
d2.Element.TiltAxis = [0 -1 0];

Create and view PCB stack antenna created using the dipole antenna object.

p1 = pcbStack(d1);
show(p1)

Create and view PCB stack antenna using the linearArray antenna array object.

p2 = pcbStack(d2);
show(p2)

Circular Microstrip Patch Antenna on Polygon Shaped Board

Create a circular microstrip patch antenna.

ant = design(patchMicrostripCircular,3e9);
ant.Substrate = dielectric("FR4");
show(ant)

c = antenna.Circle;
show(c)

c.NumPoints = 6;
c.Radius = 3*ant.Radius;
figure
show(c)

Create the PCB stack using the vertices derived from the circle shape.

v = getShapeVertices(c);
cp = antenna.Polygon(Vertices=v);
pb = pcbStack(ant);
pb.Layers{3} = cp;
pb.BoardShape = cp;
show(pb)
axis equal

Radiation Pattern of a Circular Microstrip Patch Using FEM Solver

Define dimensions of the circular patch antenna, RF connector, and FR4 dielectric substrate.

% Operating frequency
f = 2.44e9;

% Geometry
gnd = 80e-3;
h = 1.53e-3;
r = 16.8e-3;
feedloc = [5.1e-3 0];

% RF Connector dimensions
DinFeed = 1.25e-3;
DoutFeed = 4.1e-3;

% FR4 substrate
d = dielectric(Name='FR4',EpsilonR=4.3,LossTangent=0.015,Thickness=h);

Create a circular patch antenna based on these parameters.

patch = patchMicrostripCircular(GroundPlaneLength=gnd,GroundPlaneWidth=gnd,...
    Radius=r,Height=h,Substrate=d,FeedOffset=feedloc);

Convert the circular patch antenna into a PCB stack and define the feed parameters.

p = pcbStack(patch);
p.FeedViaModel = 'square';
p.FeedDiameter = DinFeed;

Refine the mesh of this antenna. Define an RF connector for this PCB stack. Compute and plot radiation pattern using the FEM solver.

[~] = mesh(p,MaxEdgeLength=0.0035);
p.SolverType = 'FEM';
connector = RFConnector(InnerRadius=0.5*DinFeed,OuterRadius=0.5*DoutFeed,...
    EpsilonR=2,PinLength=0);
p.Connector = connector;
pattern(p,f)

Create Rectangular Patch Antenna with Probe Feed

Create a rectangular patch antenna on an FR4 dielectric substrate using a pcbStack object.

patch = antenna.Rectangle(Length=0.02,Width=0.02);
gnd = antenna.Rectangle(Length=0.04,Width=0.04);
d = dielectric("FR4");
d.Thickness = 1.6e-3;

p = pcbStack;
p.BoardShape = gnd;
p.BoardThickness = 1.6e-3;
p.Layers = {patch,d,gnd};
p.FeedViaModel = "strip";

Create a ProbeFeed object and assign it to the FeedDefinitions property.

pf = ProbeFeed;
pf.ViaModel = "octagon";
pf.SignalLocations = [0 0];
pf.SignalLayers = 1;
pf.GroundLayers = 3;

p.FeedFormat = "FeedDefinitions";
p.FeedDefinitions = pf;

Visualize the antenna geometry and feed.

figure
show(p)
title("PCB Antenna with Probe Feed")

Supported Catalog Elements

The following antennas and arrays from the catalog can be converted into a PCB antenna by the pcbStack object:

Antennas

Note

Orient these antennas in the xy-plane if required, before conversion to pcbStack.

• Dipole Antennas: dipole, bowtieTriangular, bowtieRounded, and dipoleBlade.

• Fractal Antennas: fractalCarpet, fractalGasket, fractalIsland, fractalKoch, and fractalSnowflake

• Loop Antennas: loopCircular, loopRectangular

• Monopole Antennas: invertedFcoplanar, invertedLcoplanar

• Patch Antennas: patchMicrostrip, patchMicrostripCircular, patchMicrostripElliptical, patchMicrostripEnotch, patchMicrostripHnotch, patchMicrostripInsetfed, patchMicrostripTriangular

• Reflector Antennas: reflector and reflectorCircular with a finite ground plane.

• Slot Antennas: slot, vivaldi, vivaldiAntipodal, vivaldiOffsetCavity

• Spiral Antennas: spiralArchimedean, spiralEquiangular, spiralRectangular

• Other Antennas: lpda, customAntennaGeometry, customArrayGeometry

Arrays

Note

The arrays must be homogeneous, with uniform elements.

• linearArray

• circularArray

• rectangularArray

References

[1] Balanis, C. A. Antenna Theory. Analysis and Design. 3rd Ed. Hoboken, NJ: John Wiley & Sons, 2005.

[2] Stutzman, W. L. and Gary A. Thiele. Antenna Theory and Design. 3rd Ed. River Street, NJ: John Wiley & Sons, 2013.

Version History

Introduced in R2017a

R2026b: Specify feed definitions

Use the new FeedFormat and FeedDefinitions properties of the pcbStack object to define and create six types of feeds using the FeedDefinitions objects. You can control the feed geometry, orientation, and signal-ground relationships using the properties of these FeedDefinitions objects.

R2026a: Added FEM solver and RF connector support

Add RF connectors to the PCB antennas and use the finite element method (FEM) solver to compute S-parameters and visualize the far-field radiation pattern of PCB antennas designed with the pcbStack object. To enable the FEM solver, set the SolverType property to "FEM".

To use this feature, you need an RF PCB Toolbox license.