"a" wrote in message
...
I'm looking at making a parabolic reflector for a wifi link.

I'm trying to work out the distance required between the radiating element
and the reflector.
Should it be an odd number of quarter wavelengths, or an even number?

(An odd number of quarter wavelengths would be required if there is a 180
degree phase change on reflection, and
and even number would b required if there is no phase change).

So... is there a 180 degree phase change at the reflector?


It is not a mater of odd or even wavelengths. The antenna needs to be at
the focus of the reflector. The feed needs to be adjusted so it will put
most of the signal on the reflector without too much over spray.

All the above will depend on what the shape of the dish is.