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Re: Geosynchronous Satellites



on 12/23/00 10:42 PM, Jon Ogden at na9d@mindspring.com wrote:

> on 12/23/00 8:32 PM, Phil Karn at karn@ka9q.net wrote:
> 
>>> orders of magnitude.  Considering that the RF field falls of inversely
>>> proportionally to the distance between two objects, it follows then that two
>> 
>> Last time I checked, it ws inversely proportional to the SQUARE
>> of the distance.
> 
> Phil,
> 
> The RF NEAR field is inversely proportional to the square.  The FAR field
> (what we are talking about here) is inversely proportional to the distance.

Follow-up:

>From the book "Antenna Theory and Design" by Stutzman and Theil copyright
1981 John Wiley & Sons, page 22:

"If we get far enough away from any source the fields exhibit local plane
wave behavior and have a magnitude dependence of 1/r."

And then from page 17:

"In the near-field region of an antenna, terms of the field expressions with
powers of inverse r greater than one are significant compared to the
radiation fields.  The complex Poynting vector 0.5(E x H*) will then contain
terms with powers of (1/r) of three and higher in addition to the RADIATION
FIELD TERM THAT VARIES AS 1/(r^2).  (Emphasis added)

I think that proves it.

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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