[amsat-bb] Re: S band interference solution

Robert Bruninga bruninga at usna.edu
Thu Oct 5 12:28:09 PDT 2006

> > These are 100 mW devices...maximum!  That means they have 
> > to be relatively close to your QTH for you to hear them.

Two big words there.  "Relateively" and "close"...

The laws of physics trumps all opinions...

All of these give the SAME power at your antenna:
 - A 100mW device at 1 mile 
 - A 10 W  device at 10 miles
 - a 1000W  device at 100 miles.

Or this one:
 - A 100 mW device at 10 miles
 - A 10 Watt device at 100 miles
 - A 1000W device at 1000 miles LEO
 - A 400 Kw device at 20,000 miles GEO orbit

Now our birds do not have 400 Kw to downlink at S-band to
Your neighbor's WIFI at 10 miles away.

Even if you throw away 30 dB of antenna gain  (the neighbor will
not be in you main lobe, this then makes the 400W Satellite
coming in your MAIN beam no stronger than a neighbor at 10 miles
away with a 100mw device coming in the back of your dish.

Yes, it is only 100 mW, but when it is 20,000 times closer, it
is 400,000,000 times stronger.

De WB4APR, Bob

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