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pcbStack

Single-feed or multifeed PCB antenna

Description

The pcbStack object is a single-feed or multi-feed printed circuit board (PCB) antenna. The pcbStack object can be used

  • 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 with Antenna Toolbox™ antenna catalog elements

  • To convert antenna array elements to PCB stack

Note

To generate a Gerber file, a substrate layer is required. Use the Substrate property to create this layer in the PCB antenna. For more information, see Stack Conversion

Creation

Description

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

example

pcbant = pcbStack(Name,Value) sets Properties using name-value pairs. For example, pcbStack('FeedDiameter', 2.000e-04) creates a PCB antenna with a feed diameter of 2.000e-04 meters. You can specify multiple name-value pairs. Enclose each property name in quotes creates a PCB antenna, with additional properties specified by one or more name-value pair arguments. Properties not specified retain their default values.

example

pcbant = pcbStack(ant) converts any 2-D or 2.5-D antenna from the antenna catalog into a PCB antenna for further modeling and analysis. You can also use antenna array objects from the antenna array catalog elements them convert it into PCB antennas.

Properties

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Name of PCB antenna, specified a character vector.

Example: 'Name','PCBPatch'

Data Types: char | string

Revision details of PCB antenna design, specified as a character vector.

Example: 'Revision','2.0'

Data Types: char | string

Shape of PC board, specified as an object. The shape can be a rectangle or a polygon.

Example: 'BoardShape',antenna.Polygon

Thickness of PC board, specified as a positive scalar.

Example: 'BoardThickness',0.02000

Data Types: double

Metal and dielectric layers, specified 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

Feed locations for PCB antenna in Cartesian coordinates, specified as N -by-3 or N-by-4 array. You can place feed 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]

Example: 'FeedLocations',[-0.0187 0 1 2]

Data Types: double

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

Example: 'FeedDiameter',2.000e-04

Data Types: double

Electrical short locations for antenna in Cartesian coordinates, specified as a real vector of size M-by-4 array. The arrays translate to the following:

  • M-by-4 – [x, y, SigLayer, GndLayer]

Example: 'ViaLocations',[0 -0.025 1 2]

Data Types: double

Electrical shorting pin diameter between metal layers, specified a positive scalar in meters.

Example: 'ViaDiameter',1.0e-3

Data Types: double

Magnitude voltage applied at the feeds, specified as a positive scalar in volts.

Example: 'FeedVoltage',2

Data Types: double

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' – A 8-sided polyhedron approximation to the feed or via cylinder.

Example: 'FeedViaModel','octagon'

Data Types: char | string

Excitation phase at each feed, specified as a real vector in degrees.

Example: 'FeedPhase',2

Data Types: double

Lumped elements added to the antenna feed, specified as a lumped element object handle. For more information, see lumpedElement.

Example: 'Load',lumpedelement. lumpedelement is the object handle for the load created using lumpedElement.

Example: pcbant.Load = lumpedElement('Impedance',75)

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

Example: 'Tilt',90

Example: ant.Tilt = 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.

Note

The wireStack antenna object only accepts the dot method to change its properties.

Data Types: double

Tilt axis of the antenna, specified as:

  • 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, each specified as three-element vectors of Cartesian coordinates. In this case, the antenna rotates around the line joining the two points in space.

  • A string input describing simple rotations around one of the principal axes, 'X', 'Y', or 'Z'.

For more information, see Rotate Antennas and Arrays.

Example: 'TiltAxis',[0 1 0]

Example: 'TiltAxis',[0 0 0;0 1 0]

Example: ant.TiltAxis = 'Z'

Note

The wireStack antenna object only accepts the dot method to change its properties.

Data Types: double

Object Functions

showDisplay antenna or array structure; display shape as filled patch
infoDisplay information about antenna or array
axialRatioAxial ratio of antenna
beamwidthBeamwidth of antenna
chargeCharge distribution on metal or dielectric antenna or array surface
currentCurrent distribution on metal or dielectric antenna or array surface
EHfieldsElectric and magnetic fields of antennas; Embedded electric and magnetic fields of antenna element in arrays
impedanceInput impedance of antenna; scan impedance of array
meshMesh properties of metal or dielectric antenna or array structure
meshconfigChange mesh mode of antenna structure
patternRadiation pattern and phase of antenna or array; Embedded pattern of antenna element in array
patternAzimuthAzimuth pattern of antenna or array
patternElevationElevation pattern of antenna or array
returnLossReturn loss of antenna; scan return loss of array
sparametersS-parameter object
vswrVoltage standing wave ratio of antenna
plotPlot boundary of shape
layoutDisplay array or PCB stack layout

Examples

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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 = .015;
gapy = .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 = .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))

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)

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
          Tilt: 90
      TiltAxis: [1 0 0]
          Load: [1x1 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 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);

Create a circular microstrip patch.

p = patchMicrostripCircular;
d = dielectric;
d.EpsilonR = 4.4;
p.Radius = .0256;
p.Height = 1.6e-3;
p.Substrate = d;
p.GroundPlaneLength = 3*.0256;
p.GroundPlaneWidth = 3*.0256;
p.FeedOffset = [.0116 0];

Create a PCB circular microstrip 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)

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

Images using Mayhew Labs 3-D Viewer.

Create a coplanar inverted-F antenna.

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

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

la = linearArray;
la.Element = fco;
la.NumElements = 4;

Use this antenna array to create the PCB antenna.

p = pcbStack(la);

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)

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

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.

Introduced in R2017a