If you have a 1m diameter dish, F/D=0.8.
Put string up/down and side/side and measure 5mm gap error in centre.
Distortion is that the sides are forward, and top and bottom are backwards
slightly.

What is the effect on gain at 14 GHz?
What is the effect on sidelobe patterns?
What if the string gap error varies from 1 to 10mm ?

Best regards, Eric.