[Lowfer] Free Energy/QST October 1999

Sun, 10 Mar 2002 16:26:27 EST

In a message dated 03/09/2002 9:39:00 PM Eastern Standard Time, 
[email protected] writes:

<< If you are in the far field region, however, then anything you use to
 intercept the RF energy will not be directly "seen" by the transmitting
 antenna.  In the far field region, the interception antenna t is
 effectively decoupled from the transmitter, and generally causes no more
 harm than simply tuning a receiver to the transmitted frequency.

 73,

 Ralph   W5JGV / WC2XSR / 13
  >>
Hi Ralph,

I read with interest your comments about "stealing" power from a radio 
transmitter/antenna. This brings up a question that I've pondered a long time 
(probably shows my lack of knowledge about fields and waves). 

Say you have a one watt transmitter with a 100% efficient antenna so that one 
watt is "transmitted". Furthermore, say that 1000 receivers in the far field 
are tuned to that signal, each receiver's antenna input circuit "absorbing" 
one milliwatt of power (surely a receiver's antenna input circuit, even 
though decoupled from the transmitting antenna by distance, "sinks" a finite 
amount of power, especially if it is tuned to resonance on the transmitter's 
frequency). One milliwatt is probably outrageously high, but for the sake of 
arguement let's say that this is the case. If 1000 additional identical 
receivers were added, would the signal strength to all receivers drop by 3 
db? 

I know it's a dumb question, but I'm just curious.

73, Curt, K4TL