Tropospheric ducting may be an overstatement.
But it is the effect you are hoping to exploit. Tropospheric ducting is the effect caused by an inversion causing the wave front to bend and more-or-less follow the curve of the earth. It depends on the part of the wavefront in the warmer air to propagate faster thus causing the whole wavefront to bend. Get it just right and you can talk to Hawaii from SoCal with 100W on 144 MHz. Been there, done that.
I am trying to calculate the angle of refraction when the beam passes through a temperature inversion. I have a 5 mile link that has a ridge-top end-point 1200 feet above it other end-point on the vally floor. If the effect is large enough, I want to set up a second pair of 24dBi antennas and use antenna diversity.
Oh, I think I see what you are driving at. At 5mi wouldn't expect the effect to be too substantial. At 80 mi it was. (Ref my comments previously about MMDS in SoCal from mountain top to mountain top). They had to figure it out by trial and error as the results were not consistent. Eventually they figured out where to put the second dish lower on the tower in order to have consistent links.
BTW, they didn't use diversity reception, they used a voter that selected which signal was the more useful. --
Brian Lloyd 6501 Red Hook Plaza, Suite 201 [EMAIL PROTECTED] St. Thomas, VI 00802 +1.340.998.9447 - voice +1.360.838.9669 - fax GMT-4
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