Jeff,
I believe the prop mode you are taking about it called "ANTIPITAL
PROPAGATION" it is like a focusing mirror. There is a story about Ben
Franklin in one of the early sessions of congress. Being the scientist he was
he found a spot in the capitol, a particular location where he would place is
seat. He did this because he could hear his adversaries on the other side of
the room plotting their strategies. Why did this happen well because the
ceiling of the capitol was a giant dome and acted like a parabolic reflector
and the audio bounced off the ceiling to his ears. Dont believe me.. Go to
Captian Georges resturant in Virginia beach and sit in one of their domed rooms
out front and you can hear people talking on the other side of the room. I
think there is a more comon name for this mode but cant remember what is is
now.. and there have been several masters research papers published about it.
I have one of them published by Pipp et al but have never scanned it in .. it
is somewhat large. I intend to put it on my web sit at some point... a job for
the future I guess.
By the way this works for any place in the world .. supposedly.. take your
lat/lon and subtract 180 deg from it and if it hits land your in luck .. look
for stations from that area. Hummm I wonder if the other name was Antipode
focusing.. not sure anymore.
GL
Jim
------------------------------
Message: 9
Date: Thu, 31 May 2012 15:24:37 -0700 (PDT)
From: Jeff Woods <jmwooods@yahoo.com>
Subject: Re: Topband: RI1ANF
To: "Topband@contesting.com" <Topband@contesting.com>
Message-ID:
<1338503077.85738.YahooMailNeo@web39401.mail.mud.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1
Here's an interesting story:
In the early 90's, I worked as a ship-board radio officer.? At one of the
training conferences, I met a fellow RO who also worked at the McMurdo
Antarctic base when he wasn't on ships.? During one of our (many and frequent)
conversations after hours at the hotel bar, he mentioned an odd propagation
mode at 5 kHz which only seemed to be present from pole-to-pole.? The physics
of this propagation are still unclear to me, but the salient point is that he
also described the antenna.?
It was a simple dipole, cut for resonance, and strung for miles along the
icecap.? Ice is a good insulator, and the ice cap is thick enough to give a
"ground mounted" dipole reasonable height even at VLF.??
At 160m, a dipole on the ice would act as though it were essentially in
free-space.
Feel free to fact check me on this.? I was young.? We were sailors.? And we
were drinking.? :-)? But it does bode well for helping Herb get his Antarctic
merit badge some day.
-Jeff? W0ODS
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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