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Old 01-18-2005   #1 (permalink)
raklet
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Join Date: Jan 2005
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Fresnel Calculations / Interpretation of results

This is my first foray into the wireless world so suggestions, RTFMs, etc are more than welcome. I have been reading the forums and web and know that I need to do my LOS and RFLOS calculations.

Here is what I have gathered about my topography:

Site A: 4376 feet elevation
Site B: 4361 feet elevation
Obstacle: 4400 feet elevation highest point

Distance from Site A to Site B: 2.64 miles
Distance from Site A to Obstacle: 1.05 miles
Distance from Site B to Obstacle: 1.59 miles

I ran this fresnel calculator and was told that my 1st Fresnel Zone is 36 ft. and the 60% level is 30 ft.

I am assuming this means I need 30 ft of free space from the radio waves to the obstacle at the point which the waves pass over the obstacle. So, if Site A is 4376 ft, I would need a 24 ft mast to get LOS and then an additional 30 ft to obtain RFLOS. Are my assumptions about the information from the calculator correct? Do I need a 54 ft mast?

*Note about the obstacle. It is the tail end of a hill with a not too steep slope. The hill is barren with light growth of scrub grass, no trees, and no major rock outcroppings. Does the type of obstacle make a difference in the calculation of RFLOS? Perhaps my mast does not need to be as high as I have calculated?

See attached picture for an overhead view of the site.

Thanks for any help,

Raklet

Last edited by raklet : 01-18-2005 at 06:04 PM.
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