Seems that you measured your dish quiet precisely. Program shows offset angle 22,6* (as you mentioned earlier), and opening angle precisely 80*. I circled those numbers red.
View attachment 69077 View attachment 69078 Circled green distances from Focus to UP and DOWN points of antenna. And blue is distance from Focus till you know what.... "Le point G"
But, now we will only use opening angle of your antenna, which is 80*.
So, lets draw two crossing lines with 80* between them. Something like this
View attachment 69079
Humm, according to your program the measurements for my 1.2m CM are A=1211mm, B=712mm and the opening angle is 80⁰.
My measurements were, A=1230, B=720 and the opening angle was 78,2⁰
My measurements were taken with a quality steel tape measure.
The angle was taken with a stabila electronic angle finder (very accurate 0.0005⁰ ) and I took my time and rechecked all measurements, I placed my straight edge from point A (top of dish face) to the centre of the lnb and measured the angle. then repeated the procedure for point B (bottom of dish face). I then added the two angles together to get 78.2⁰
I used the point arrowed in the picture as the centre of the focus for the lnb and therefore my point for measurements. Anyone have any differing thoughts on this, as I couldn't find any info re this point!
The difference in these two sets of measurements would suggest that the lnb support arms are either holding the lnb in a slightly wrong position too far away from the dish face or possibly the lnb wants pulling forward towards the dish face! The only problem is if I pull the lnb forward, the signal gets weaker?I spent a lot of time when I set this dish up adjusting the position of the lnb and it's skew for it to end up where it is now. But the calcs of the parabola4 program suggest it wants to be moved?
When I have some spare time, maybe mid week, I shall re check all these measurements again!