Inverting reflectorCylindrical - to allow for curved ground plane simulations

Hello,

As above I am trying to invert reflectorCylindrical:

i.e. I would like the dipole (or other exciter) to be above the curved surface of the reflector like so:

this requires the depth to be set to a negative value (i.e. inverting the reflector) but the reflectorCylindrical function does not permit this.

I made a new function called reflectorCylindricalInverted which does the following:

• permits depth to be a negative number, by removing the 'positive' requirement - line 146
• remove the positive tolerance (1e-6) value which was preventing negative numbers also - line 147

function set.Depth(obj,propVal)

%tol = 1e-6;

validateattributes(propVal,{'numeric'},...

{'nonempty','scalar','real','nonnan','finite',...

},'reflectorCylindrical', 'Depth');

if isPropertyChanged(obj,obj.Depth,propVal)

obj.Depth = propVal;

end

end

end

I am then able to successfully generate an inverted reflector:

Exciter: [1×1 dipole]

GroundPlaneLength: 0.2000

GroundPlaneWidth: 0.2000

Spacing: 0.0750

Depth: -0.0750

EnableProbeFeed: 0

Conductor: [1×1 metal]

Tilt: 0

TiltAxis: [1 0 0]

Load: [1×1 lumpedElement]

However, when I run show(ant) I get the following error:

Error using reflectorCylindricalInverted/createGeometry

The value specified for Depth should be less than or equal to 0.1.

Error in em.MeshGeometry/protectedshow

Error in em.MeshGeometryAnalysis/show (line 31)

protectedshow(obj);

Does anyone have any insight into a possible solution for this problem? If anyone is particularly familiar with the reflector functions, that would be very helpful.

[Alexander]

I've managed to flip the reflector, however when running the pattern function from the antenna toolbox I get the following error:

Output argument "gr" (and possibly others) not assigned a value in the execution with "em.MeshGeometry/getNewMesherGrowthRate" function.

Error in em.MeshGeometry/getAutoMeshGrowthRate

Error in reflectorCylindricalInverted/calculateMeshParams (line 163)

growthRate = getAutoMeshGrowthRate(obj);

Error in em.MeshGeometry/getMesh

Error in em.EmStructures/analyze

Error in em.FieldAnalysisWithFeed/pattern (line 177)

analyze(obj,frequency,ElemNumber,parseobj.Results.Termination);

Answer 1

[Alan]

Hi Alexander,

From what I understand, you want to create an antenna where the dipole faces the outside surface of the cylindrical reflector.

If modifying the inbuilt function is not possible, you could create an STL file containing the 3D design of the cylindrical surface and the dipole with the required orientation. Then, create a custom shaped antenna using the “customAntennaStl” function:

ant = customAntennaStl(FileName = 'design.stl'); 

Finally, use the “createFeed” function to set the feed point on the dipole:

ant.createFeed();