Problem with custom antenna magnitude response import

Hi there,

There is a problem when we try importing a custom magnitude response in the Simulink environment. We have the antenna radiating at maximum 10.9 dBi directivity, but it is only displays 8.78dBi in the antenna analysis tool. Basically, this is the code which we use to import:

filename = 'data.txt';
delimiterIn = ' ';
A = importdata(filename,delimiterIn);
mag_response = A(:,end-2);
phase_response = A(:,end-1);
mag_response = [mag_response; mag_response(end-180:end)];
phase_response = [phase_response; phase_response(end-180:end)];
m1 = vec2mat(mag_response,181);
m2 = vec2mat(phase_response,181);
m1 = m1';
m1 = m2';

After that we invoke m1 in the custom antenna gui in simulink and the image we get with the pattern is shown below.

Notice that we get maximum directivity under 9 dBi, whereas the maximum values in the matrix is 10.14 dBi. I am not sure what could cause this.

Is is something to do with the precision of the array?

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Answer 1

[Honglei Chen]

The magnitude and phase patterns are meant to be field patterns, not directivity patterns. Note that directivity has no phase so if your m1 is directivity, then m2 should just be all zeros. Is that the case?

HTH

[Cristian Alistarh]

Hi HTH,

Many thanks for your clarification. I will see more about this on Monday since I do not have access to CST now, but I would like to add that we can extract the phase patterns as well for the elevation, and that is what we input in the phase response section.

I guess that is not correct from what you are suggesting.

Thank you.

All the best,

Cristian

[Honglei Chen]

If you have a phase pattern, then my understanding is you have a field pattern, in that case it is not the same as directivity. So you shouldn't expect the directivity value match the maximum value in your field pattern since the directivity is the power pattern normalized by the total radiated power.

HTH