[MLB-WIRELESS] longest link?

[paul van den bergen]

On Tue, 28 Oct 2003 04:25 pm, Ed wrote:
> How about over water with say 100m clearance?

you'd have to do the sums... I was quoting from memory because the I couldn't 
remember the website that did the original calc... which, when you think 
about it, does not bode well....

If you presume a clear LOS and you know your Freznel Zone angle you can work 
out a relationship between the distance between the two points and the 
maximum width of the Freznel zone.  The height of the Freznel Zone at the 
centre plus the drop in height as the earth drops away from that centre will 
give you the height of the antenna mount you will need at both ends (or 
double at one end.)... for most calcs. you can ignore paralax error (due to 
the fact the antenna poles are no longer parallel and hence slightly shorter 
wrt one another).

still and inverse squared relationship between data rate and distance... (or 
power and distance)
-- 
Dr Paul van den Bergen
Centre for Advanced Internet Architectures
caia.swin.edu.au
pvandenbergen at swin.edu.au
IM:bulwynkl2002
"And some run up hill and down dale, knapping the chucky stones 
to pieces wi' hammers, like so many road makers run daft. 
They say it is to see how the world was made."
Sir Walter Scott, St. Ronan's Well 1824 


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