Comparison between mask and far field

Fabio Borrelli
Fabio Borrelli Altair Community Member
edited June 2021 in Community Q&A

Hi there,

I have a problem relative the POSTFEKO ambient and the creation of the masks:
I'm designing a quadrihelix antenna, and I created two masks (greater than and less than) to make a gain optimisation. So, after OPTOFEKO worked, I step to the POSTFEKO ambient to see the farfield and I would like to make a comparison on the same chart with the two masks.
I think that I could do that only in the Cartesian Graph, and it's not a problem for me.
I created the two masks from 0 to 180, where in X axis I put the angle value, in Y axis I put the gain value in natural numbers.

When I look at the masks graph in POSTFEKO, according to the Feko's example guide, I scale the two mask of 180° and I do a math operation (20LOG (self) ) on the two masks in order to obtain the Y value in dB, so I can compare the masks with the farfield in dB.

This is my argument.
The problem is this: the masks doesn't fit with the far field optimisation. So, when I see the comparison chart, it doesn't make sense.
I expect the farfield curve it's located between the two masks, but it is positioned above them.

I attach three images: one of these shows my result, the other what I would like and the masks value (they are quiet simple, but it's only because I need to make some fast prove to risolve this problem).


P.S: in the result, the masks are the blue and green curves. The red one is the far field.

Thank you all in advance.

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