[sdiy] generators/antennas analogy?

[Scott Gravenhorst]

Radio, X-rays, light, etc. are all radiant electromagnetic
energy.  If one places an absorbing material in it's path,
that which is behind the obstacle receives a lesser amount
of that energy.  But as far as a change in the energy input
required by the generating device; ask this question:  If 
one places something black in the path of light from a bulb
(black opaque things absorb most of the light), does the 
current or heat of the bulb vary?  I think we are confusing 
the transformer effect (which is  purely a magnetic 
phenomenon) with radiant electromagnetic energy, which is 
quite different.  A radio station and a receiver do not form
an air core transformer.  The amount of power used by the
transmitter is controlled by Ohm's Law, not the number of 
receivers.

harry <harrybissell at prodigy.net> wrote:
>Is this an 'urban legend' ???
>
>There are some people who have gotten "free' power by receiving RF
>stations from VERY close up... now that might make a little dent but I
>doubt that anyone could judge "listenership" from plate current etc...
>
>H^) harry
>
>Lincoln Fong wrote:
>
>> Whilst I am familiar with the idea of 'back emf' in a generator there is
>> something I have never understood which Im sure someone can clear up.
>>
>> I once heard that Radio and TV stations can judge audience figures by the
>> amount of power 'absorbed' ie the Watts or MWatts they have to pump out. On
>> one level this makes sense. A popular station would need only the weakest of
>> transmitters if this were not so. But can the resonance of millions of tuned
>> circuits really indicate power usage that accurately? And if not then how do
>> they judge audience figures? I don't really buy the argument that grid power
>> usage can accurately reflect these things when so many programmes start at
>> exactly the same time.
>>
>> Lincoln
>

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