To: | "David G4FTC" <g4ftc@hotmail.com>, amps@contesting.com |
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Subject: | Re: [Amps] 10dB and propagation |
From: | Bill Fuqua <wlfuqu00@uky.edu> |
Date: | Mon, 07 Feb 2005 14:18:50 -0500 |
List-post: | <mailto:amps@contesting.com> |
In the late sixties and early seventies an EE professor of mine
was doing research into plasma physics studying the effects of ionization
on radio propagation. The study had to do with studying the nonlinearity of
plasmas which causes a high degree of signal scrambling (intermodulation,
cross-modulation and harmonic generation) when the plasma density is high
(such as you would have after a nuclear atmospheric blast). There were
concerns about communication and radar operations in such
environments. There was just only so much he could do in the plasma
physics lab inside the long glass tubes with water cooled magnets around
them and KW RF generators. He propose that the university allow him to build a large transmitter and antenna system (cloud warmer) to produce ionization of the upper atmosphere and then probe it with other radio signals to characterize the non-linearity of the signal path. The altitude of the zone of plasma that would be produced was related to the frequency of the high power signal. This was related to mean distance between the atoms in that region. Also, the probe frequencies were not chosen as those that would be most refracted or reflected which is related to the electron density (plasma resonance). The idea was not to optimize the return signal but to determine what would happen to signals that tried to pass thru the plasma (some very small amount would be returned). The department chairman pulled the funds so that he could have the front office remodeled and others got to do this work. 73 Bill wa4lav At 06:45 PM 2/7/2005 +0000, David G4FTC wrote: W2DTC wrote:
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