[HCDX] HF Propagation From Thailand

["Thomas Giella KN4LF" <kn4lf@xxxxxxxxxxxxxxx>]

Jerry KC2UT:
.....Judging by the way that signal sounds, very non auroral like and consistently there day from day and season to season, I think it must be the 16.000 mile path, through all darkness and low latitude, because even during high auroral periods I hear these guys, day in and day out.....

  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

KN4LF Daily Solar Space Weather & Geomagnetic Data Archive &
Daily HF/MF Radio Propagation Outlook:
http://www.kn4lf.com/kn4lf5.htm
 
KN4LF 160 Meter Amateur Radio Resources & More:
http://www.kn4lf.com/kn4lf.htm




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