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Re: Geosynchronous Satellites




> My original post quoted here:
> 
>> Considering that the RF field falls of inversely
>> proportionally to the distance between two objects.....
> 
> I said RF FIELD.  And then I quoted to you from a TEXTBOOK.
> 
> I think I got that RIGHT, Phil.

Phil,

I thought about this some more.  We are BOTH correct, but I did make an
error in my original posting.

My statement that the RF field strength is inversely proportional to the
distance from an object is correct.  Where you are correct and where I made
the mistake was in speaking of POWER.  Field strength is a voltage.  When
moving over to speaking of power, you are correct since Power involves the
square of the voltage.

So my point is even more stronger in my orignal post!

For a given link margin at a leo orbit, you would need 400 times more power
from a geo-synchronous orbit to get the same link budget!  So if a satellite
has a 5 watt downlink on an FM channel (what we were talking about), in
order to receive that same signal at the same level with the same ground set
up at a Geo-synch orbit, we are now talking about a power of 2000 Watts!
Again, this is assuming that the geo-synch orbit is approximately two orders
of magnitude or 20 times higher than the LEO orbit.

So overall my point was still valid.  But I did confuse my units.

73,

Jon
NA9D

-------------------------------------
Jon Ogden
NA9D (ex: KE9NA)

Member:  ARRL, AMSAT, DXCC, NRA

http://www.qsl.net/ke9na

"A life lived in fear is a life half lived."

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