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From: karsh@geowhiz.UUCP (Bruce Karsh)
Newsgroups: net.physics
Subject: Re: freq. spectrum
Message-ID: <210@geowhiz.UUCP>
Date: Fri, 19-Jul-85 06:27:19 EDT
Article-I.D.: geowhiz.210
Posted: Fri Jul 19 06:27:19 1985
Date-Received: Sun, 21-Jul-85 01:21:13 EDT
References: <99@biomed.UUCP>
Reply-To: karsh@geowhiz.UUCP (Bruce Karsh)
Organization: UW Madison, Geology Dept.
Lines: 30

In article <99@biomed.UUCP> lagasse@biomed.UUCP (Robert C. Lagasse) writes:
>
>  Now, if I want to transmit at a frequency of, say, 1 kHz which is
>obviously in the audio (20 Hz-18 kHz) range, do I just take an audio
>oscillator, feed it to an audio amp, and instead of driving a speaker
>(please don't laugh) connect it to a 300 km long antenna (speed of light /
>freq. = wavelength) with some sort of impedence matching network?  In other
>words, how high up in frequency must one go before you can generate "RF", on
>the other hand, how low in frequency can you go before you begin to affect
>objects, people, etc.  I mean, if I build an RF transmitter for 10 Hertz and
>connect it to the proper aerial (about 30 Mm long), would it shake every
>object that would resonate at 10 Hertz even though it is "RF" and not audio,
>or not??

  The military's project ELF (extremely low frequency) project in Clam Lake,
Wisconsin broadcasts at 60 hz on huge (many miles long) antennas.  The intent
is to be able to communicate with submarines.  (Skin depth in water is much
bigger at lower frequencies.)

  There have been a lot of complaints, lawsuits, etc. about possible health
and environmental effects.

   We did some seismic experiments up there.  I understand that when ELF
was broadcasting, our seismic cables went wild.
-- 
Bruce Karsh                           |
U. Wisc. Dept. Geology and Geophysics |
1215 W Dayton, Madison, WI 53706      | This space for rent.
(608) 262-1697                        |
{ihnp4,seismo}!uwvax!geowhiz!karsh    |