RE: [HCDX] Re: Antipodal Focusing

["Marcelo Toniolo" <dxnz@xxxxxxxxxx>]

Hello Glenn

Perhaps this was a misunderstanding and Thomas used incorrect words to
explain a correct thinking.
I just checked GeoClock and a Sunrise in Florida at this time of the
year corresponds to almost a perfect Sunset in Bangkok, Thailand.

Yes, Thailand is not geographically antipodal of USA but they match a
Sunset/Sunrise Gray Line and this explains the good propagation noticed
by Thomas.

Marcelo





-----Original Message-----
From: hard-core-dx-bounces@xxxxxxxxxxxxxxxx
[mailto:hard-core-dx-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Glenn
Hau-ser
Sent: Saturday, 6 September 2003 9:09 a.m.
To: hard-core-dx@xxxxxxxxxxxxxxxx
Subject: [HCDX] Re: Antipodal Focusing





Sorry to break this to you, but Thailand is nowhere near antipodal from
the 
US. For starters both are in the Northern Hemisphere... Unfortunately
there 
is little land on the opposite side of the globe from the USA --- in the

Indian Ocean.

73, Glenn Hauser

Yes Radio Thailand on 7260 kc at my local sunrise sure is stable here in

Central Florida, even more so then R. Australia on 9580 kc. There is a 
propagation mode called anti-podal focusing. If you are at or very near
the 
opposite side of the planet from the station you are receiving from and
the 
aurora ovals are retracted, the RF signal can travel on all available 
geometric (GC) great circle paths, all coming together at the opposite
side 
of the planet and adding up to a big signal. Antipodal focusing may
explain 
Radio Thailand's big signal here in the U.S. Antipodal focusing is best
at 
the fall/spring equinox of which we are fast approaching.
  A neat HF propagation project would be to keep track of Radio
Thailand's 
7260 kc signal every morning at local sunrise here in the U.S. for 365
days 
and plot it's signal strength versus the Ap index.

73,
Thomas F. Giella, KN4LF
Plant City, FL, USA
EL87WX

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THE INFORMATION IN THIS ARTICLE IS FREE. It may be copied, distributed
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