The final product only needs to be accurate to about 1mm as this will only shift the frequency within the range of the 802.11 spectrum. A smaller cavity length will shift the frequency response to that slot to a higher channel. A longer slot cavity length will shift it down.
|Not very exciting, but works well out to ~2Km. (with a cone probe it was working well at 3km)
|Shows the reflector mounting
| N-Socket with 1/4 wavelength copper wire
(including the length of the bit of the
N-Socket it is soldered into).
This becomes the probe for the antenna.
|Shows the probe mounted.
A conical feed is a much better probe. It is made from a 20mm x 40mm piece of copper and rolled into a cone. It is slightly harder to make, but it is worthwhile.
Cut the red area from the copper and roll into a cone. Solder onto an N-Connector so that the cones base will be exactly half way across the cavity.
Nb.The 10mm hole in the waveguide for the Nconnector will be too small for a cone probe. You will need to drill it out to 16mm. Do this in small increments, widening the hole one or two drill bit sizes at a time. It will make a much neater hole.