Trouble in codegen customized antenna pattern

Hello,

I am trying to use codegen on a customized antenna pattern, basically this,

pattern = phased.CustomAntennaElement('AzimuthAngles',x.azim,'ElevationAngles',x.elev, ...

'MagnitudePattern',(x.pat_azEl),'PhasePattern',45*ones(size(x.pat_azEl)));

but I keep getting the following error message:

"??? Expression could not be reduced to a constant.", which points to line 1014 of the CustomAntennaElement.m function when setting the phase.

Does Matlab Coder not support custom antenna functions? Could anybody give me some advice please?

[Honglei Chen]

Thansk for reporting this. We've idenfitied the issue and will fix it in a future release. Please see the ansewr below for a workaround.

Answer 1

[Honglei Chen]

I don't know how x is formed, but here is an example you can take a look, that generates the code. The main idea is to push pattern computation to a separate function and use coder.extrinsic to compute it first then save as a constant.

The main function looks like this

function pattern = phasedArrayWrapper()
coder.extrinsic('getPattern');
AzimuthAngles = -180:180;
ElevationAngles = -90:90;

MagnitudePattern = coder.const(getPattern(AzimuthAngles,ElevationAngles));
phasepattern = zeros(size(MagnitudePattern));
ant = phased.CustomAntennaElement('AzimuthAngles',AzimuthAngles,'ElevationAngles',ElevationAngles, ...
    'MagnitudePattern',MagnitudePattern,'PhasePattern',phasepattern);
pattern = ant(3e8,[0;0]);
end

The supporting function, which needs to be on path, looks like below

function pat = getPattern(AzimuthAngles,ElevationAngles)
pat = mag2db(repmat(cosd(ElevationAngles)', ...
    1,numel(AzimuthAngles)));
end

The codegen command is shown below

>> codegen phasedArrayWrapper
Code generation successful.

HTH

[Tor Viscor]

Thanks for the answer.

I tried your way and also something similar,by saving the pattern information in a variable and loaded it in the main code for codegen. But both resulted in that error message. Could it be an issue with the pattern type I am trying to use in the custom antenna function?

Please see below:

% this is the pattern to be used in the custom antenna element function, saved in 'cosVar'

antenna = phased.CosineAntennaElement;

TRM = phased.ULA('NumElements',6,'Element',antenna,'ArrayAxis','y','ElementSpacing',lambda/2);

[pat_azEl,azim, elev ] = pattern(TRM,fc,-180:0.05:180,-90:0.05:90);

save('cosVar.mat','pat_azEl','azim','elev');

*************************************************************

coder.load('cosVar')

TRM_pattern = phased.CustomAntennaElement('AzimuthAngles',azim,'ElevationAngles',elev,'MagnitudePattern',(pat_azEl),'PhasePattern',0*ones(size(pat_azEl)));