Long Distance link through cloud and fog

[raytaylor]

Hi everyone.

I am about to look at using a couple of powerstation2's for a long distance wifi link. They will be connected to 19dbi parabolic grid antennas pointed at each other.

This will be an interesting link because it will be going from a base station at sea level to a remote station 600m above sea level that through most winter evenings or cloudy days, will be in or above clouds and fog.

Distance will be about 20km but i hope to put in another link about 45km using the same hardware going from 40m Above Sea Level to 1000m ASL.

Does anyone know if these links would be affected by the cloud or fog?
There will definitley be cloud and at night up at the lookout you cannot see the city lights below when clouds are going underneath - also the lookout is only 400m high. I am using 2.4ghz powerstation2's

[WHT]

Dang it...where did my reply disappear to? Let me try again.

Fog, clouds, and rain do not significantly affect 2.4 and 5.8 Gig wireless...but the temperature difference associated with those events can affect you signal path. You may have to have a more robust fade margin allowance.

For a 20 KM (12 miles) hop:
PS2 -> PS2 @ 36 MBps data speeds: 15 dB fade margin
PS2 -> PS2 @ 24 MBps data speeds: 20 dB fade margin

For a 45 KM (27 miles) hop:
PS2 -> PS2 @ 36 MBps data speeds:   8 dB fade margin
PS2 -> PS2 @ 24 MBps data speeds: 13 dB fade margin
PS2 -> PS2 @ 12 MBps data speeds: 18 dB fade margin
PS2 -> PS2 @   6 MBps data speeds: 21 dB fade margin

This is assuming a fairly flat shot where the depression angle caused by the temperature inversion induced diffraction is only a few degrees. In your case where you are looking down from a much steeper angle, the diffraction would be less and you may not need a more robust link.

[raytaylor]

Awesome, that makes alot of sense. Basically if i design the 50km link using hardware / power of a 80km link it should be stable through the cloud. :-)