Re: just wondering (Schumann resonance)

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Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net> 


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Thursday, May 06, 2004 5:15 AM
Subject: RE: just wondering (Schumann resonance)


 > Original poster: "Steve Conner" <steve.conner-at-optosci-dot-com>
 >
 > I have a couple of thoughts about the Schumann resonance.
 >
 > As a radio ham I know about propagation and stuff. And I understand the
 > Schumann resonance is a standing wave caused by a radio wave that, in
 > wavelength terms, fits exactly once (or a whole number of times) round the
 > earth. (please correct me if I'm wrong.)

Exactly right..

 >
 > Now, if my "standing wave" analogy is correct, I would imagine the
 > propagation path for the wave that forms the Schumann resonance is pretty
 > lossy. When talking to very high powered foreign stations on the HF band,
I
 > could often hear a distinct "echo" on their signal, which is of course
 > caused by their radio waves reaching me twice, the short way round the
 > world, and the long way.

It is...

 >
 > Anyway, from observations like these, I would estimate the loss for a trip
 > round the world is over 100dB. I was working at 10s of MHz, it would of
 > course be lower at the 10s of Hz where the Schumann resonance happens. But
 > even assuming the loss goes down in proportion to the frequency, it's
still
 > a 40dB loss (40dB= 1/10000) at 10Hz.
 >
 > So how on earth you could ever excite a resonance in such a lossy system,
 > using even the most powerful transmitter ever made, I don't know.

You can actually measure the Schumann resonance by hooking up a suitable
spectrum analyzer to an antenna and integrating for a good long time.
You'll see a small hump in the noise floor around 7-8 Hz. The power into the
"resonance" is from lightning.  The Q isn't all that high (perhaps 3?), and
recall, it's not the same distance around the world every direction,
particularly when the propagation path is really like a big waveguide (below
cutoff) between the surface and the ionosphere, where the waveguide size is
varying as are the wall properties.


 >
 > If these loss figures are ballpark, it blows all that "wireless death ray"
 > cr*p out the water too: For instance, Tesla couldn't have caused the
 > Tunguska explosion ;) without causing an explosion 40dB bigger at his
 > transmitter site, and I think folks would have noticed New York missing
:)))
 >
 > Steve C.
 >
 >