Platform of a Parabolic Reflector Different Pattern than built-in Parabolic Reflector Object

I wish to simulate a parabolic reflector with RMS surface error similar to the last part of this write up:

https://www.mathworks.com/help/antenna/ug/pattern-analysis-of-the-symmetric-parabolic-reflector.html

However, I have found that the process of importing a reflector using a platform in an installed antenna will always result in a lower gain of about 4 dB. The nulls also appear to not be in exactly the same place.

Does anyone know why this might be the case? The code is attached.

I have tried remeshing the STL and keeping the original (should be the same as the mesh created by the parabolic reflector object) and have not seen a difference. The solver is set to MoM-PO and the feed setup is exactly the same. Perhaps I am missing something.

Many thanks in advance.

Answer 1

[Naren]

Hello John,

I understand you are trying to simulate a parabolic reflector with RMS surface error, and you wish to compare the outputs of parabolic reflector and installed antenna. However, there is a mismatch between both results.

The difference in levels that you found is due to an issue with MATLAB when analysing installed antennas with custom meshes. Result variation is observed when pattern is plotted after tilting the antenna and compared with reflector parabolic. Mesh and feed are tilted for both custom dual reflectors and installed antenna but slight variation in result is observed.

It's worth noting that this problem does not occur in R2023b.

Regards, Naren