[NLRS] Path loss calculations

Fri, 5 Mar 2004 17:34:26 -0600

Hey Donn, that sounds good.  I will look at that this weekend perhaps.  I
appreciate the info.

As for the humidity thing.  Roger roger.  I was refering to humidity I guess
in a lump sum of all things.  My calculations were based on absolute
humidity for grams / meter-cubed water vapor based on a celcius temperature,
then multiplied by the relative humidity as a percentage.  At least thats
what the ARRL UHF/Microwave book shows.  It is a good point for sure, dont
want to show everyone that RH is just the only thing that is taken into
account for water vapor attenuation.

As for LOS communications, thanks for the rule of thumb.  That gives us all
a good idea of where real tropo scatter begins.  I was hoping it was a LOS
path, but never gave it any numerical thought to see if it was even close.
Now I know!

73

Mike - KM0T

----- Original Message ----- 
From: "Donn Baker" <[email protected]>
To: "Mike A. King - KM0T" <[email protected]>; "Northern Lights Radio
Society" <[email protected]>
Sent: Friday, March 05, 2004 5:11 PM
Subject: RE: [NLRS] Path loss calculations

> Hi again, guys,
> I downloaded Technical Note 101.  This may be the jackpot.  There are
> chapters on LOS, troposcatter, etc.  There's a LOT of stuff in it.  Its
> dated 1965, revised 1967.  Two volumes: Vol I seems to be the "good
stuff,"
> while Vol II is Annexes (Appendicies) with what appears to be the base
data
> for the formulas in Vol I.  I didn't look too closely at Vol II.  Each vol
> runs to 200 or more pages.  Unzipped, it looks like more than 20 MB.
>
> As would be expected, math heavy, but I didn't see anything that scared
me,
> and I'm pretty math-phobic, so I don't it'll be a problem for anyone else.
> There are tables, charts, and nomographs if you don't want to crunch
numbers.
>
> 73 Donn
> WA2VOI/0
>
> >All I found for Atmosphereic Absorption (oxygen and water vapor) was a
> graph.  However, I did find a reference to the source for the graph.  See:
> >NBS (NIST)
> >Technical Note 101
> >Transmission Loss Predictions for
> >Troposheric Communication Circuits
> >Volumes I & II
> ><http://its.bldrdoc.gov/pub/ntia-rpt/tn101/>
> >
> >Its LARGE, ~15MB, and I haven't downloaded it (yet ?).  The Contents look
> interesting, though.
> >**************
>
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