[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: Geosynchronous Satellites



Jon,
You are confusing the "Field" with the "power received".  Yes, the field
is 1/r, but the power received from such a "field" is 1/r squared...

bob

On Sat, 23 Dec 2000, Jon Ogden wrote:

> 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."
> 
> ----
> Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
> 

de WB4APR@amsat.org, Bob

See my APRS LIVE pages    http://web.usna.navy.mil/~bruninga/aprs.html
See APRS SATELLITES       http://web.usna.navy.mil/~bruninga/astars.html
See MIM/Mic-E/Mic-Lite    http://www.tapr.org/tapr/html/mic-e.html

----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home