shape has NaN vertices when adding new shapes to the aggregate shape encloses a void; error assigning shape to antenna

I am creating a PCB antenna pattern adding together copper Polygons and rectangles to make the PCB trace pattern. The copper traces short back on themself forming a region with voids in it.

I have used shape.Rectangle() and shape.Polygon() to create the elements and added them together.

When I show the copper it looks right (needs a little cleanup, but OK).

When I show or mesh the antenna it throws a triangulation error.

Adding the last rectangle that closes the shape causes an NaN. This error was NOT happening in another pattern (make a shape, remove a notch from an edge, bridge the notch with a rectangle...).

...

copper = shape.Polygon('Vertices', 0.001*[MinX MinY 0; MinX MaxY 0; MaxX MaxY 0; MaxX MinY 0]);

stem = shape.Rectangle ("Center", 0.001*[StemX MaxY+StemLen/2], 'Length', 0.001*StemWid, 'Width', 0.001*StemLen);

copper = copper + stem;

... add rectangles till a closed loop is formed. feed point in stem and loading reactance at far end...

...

show(copper); % looks OK other than jagged corners, see below

Ant = customAntenna ('Shape', copper, 'Load', Load);

show(Ant); % --> error. If commented, mesh(Ant, ...) throws similar error (same error, different call back path)

createFeed (Ant, FeedPoint, 1);

meshconfig (Ant, 'manual');

mesh(Ant, 'MaxEdgeLength', .06,'MinEdgeLength', 0.0005);

show(Ant) --> error

Error using triangulation

The coordinates of the input points must be finite values; Inf and NaN are not permitted.

Error in customAntenna/createGeometry (line 235)

tri = triangulation(tt.ConnectivityList,vert);

Error in em.MeshGeometry/protectedshow

Error in em.MeshGeometryAnalysis/show (line 31)

protectedshow(obj,varargin{:});

mesh(Ant, 'MaxEdgeLength', .06,'MinEdgeLength', 0.0005); --> error

Error using triangulation

The coordinates of the input points must be finite values; Inf and NaN are not permitted.

Error in customAntenna/createGeometry (line 235)

tri = triangulation(tt.ConnectivityList,vert);

Error in customAntenna/meshGenerator (line 306)

createGeometry(obj);

Error in em.MeshGeometry/updateMesh

Error in em.MeshGeometry/protectedmesh

Error in em.MeshGeometryAnalysis/mesh (line 66)

protectedmesh(obj,varargin{:});

Error in patchNotch (line 89)

mesh(Ant, 'MaxEdgeLength', .06,'MinEdgeLength', 0.0005);

[Johnny Himbele]

Hi Jeffrey,

It looks like you are trying to create a PCB antenna. Have you consider using the pcbStack object?

p = pcbStack;
p.Layers{1} = copper;
% Make sure to update the BoardShape and FeedLocations

[Jeffrey Andle]

I also tried that. I am having issues with via/feed/load there but it works. Offline, I received help from an indirect contact at Matlab:

Hi Jeffrey,

I have attached modified versions of shared scripts above.

For NaN issues in customShapeLoop.m,CustomNotch_3D, issue occurs when creating a mesh internally for the antenna which will be fixed in 25a. As a workaround, we can input a shape without no-NaN vertices by meshing it first and creating a triangulation and making a new shape out of it. This is included in the modified script and should run fine in 24a.

For pcbShapeAntenna, using finer minedgelength is generating more tetrahedra leading to more run time. I modified it to use only maxedgelength but a little finer so as to run quicker.

Hope this helps.

Please reach out for any further clarifications or questions.

Regards,

Sharath.

[Johnny Himbele]

I'm gald to hear you've got the help.

What kinds of the via/feed/load issues are you having?

[Jeffrey Andle]

I reverted to just testing a transmission line 0.1mm over GND, 0.16mm wide, 100mm long.

I intend a feed at +X and a 50 Ohm load through a via at -X. The line is shorted with the via and open when I comment it, so I guess via and feed are working, but the load is not.

close all
clear

freq = linspace(100e6, 1000e6, 10);

% test simple transmission line 150mm long
% via, load, line, feed, via
ant = pcbStack();
ant.BoardShape = antenna.Rectangle("Length", 0.15, "Width", 0.075);
ant.BoardThickness = 0.0001;
L1 = antenna.Rectangle("Length", 0.1, "Width", 0.00016);
L2 = dielectric("FR4");
L2.EpsilonR= 4.1;
L2.Thickness=ant.BoardThickness;
L3 = ant.BoardShape;
ant.Layers = {L1 L2 L3};

ant.FeedDiameter = 0.00005;
ant.FeedLocations = [0.0498 0 1 3];
ant.ViaDiameter = 0.00005;
ant.ViaLocations = [-0.0498 0 1 3];% ; 0.0498 0 1 3];

Load = [lumpedElement('Impedance', 50, 'Location', [-0.0496 0 ant.BoardThickness])]; % lumpedElement('Impedance', 50, 'Location', [0.0496 0 ant.BoardThickness])];
ant.Load = Load;

meshconfig (Ant, 'manual');
mesh(ant, 'MaxEdgeLength', .03);

figure
Z = impedance(Ant, freq);
plot (freq, real(Z), freq, imag(Z))
grid on