In article , Eric
Johnston writes
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 ?

Eric,

I don't have the book on hand so can't I look it up, but I seem to
recall graphs of this in the ARRL Antenna Book (at least for the effect
on gain). It could be worth finding a copy as a graph would be easier
to make an approximation from than trying to work the formulas!

Andrew Williamson GI0NWG / AC6WI
Homepage = http://www.gi0nwg.freeserve.co.uk/

One of the ZL9CI gang
http://www.qsl.net/zl9ci/