Propagation to Eastern U.S.
Following are the comments of Bob Brown, NM7M regarding propagation
between Scarborough Reef and the eastern half of the United States:
A few bits of data:
Calls Region Distance Path
W1-W3 NYC area 13,700 km polar
W4 Atlanta, GA 14,100 km auroral zone
W5 Dallas, TX 13,500 km sub-auroral
W8 Cleveland, OH 13,400 km polar
W9 Chicago, IL 13,200 km polar
While the distances are not very different, the paths tell you
something of the problem of making contacts from Scarborough Reef.
Being a low-latitude station, it does well with other low-latitude
locations - JA, VK, ZL, ZS, LU, PY and even W6. But going to more
northerly sites, the paths become more difficult.
So for the USA call districts shown above, contacts are at the
mercy of geomagnetic activity and whether the solar wind impacts
seriously on the high-latitude field lines. Any significant geo-
magnetic activity could disrupt the F-region electron densities
(e.g., MUFs) and propagation paths on the higher bands, e.g., 14
MHz, across high latitudes as well as mess up the possibility of
contacts with the USA from BS7.
Right now, the Weekly Boulder Report, "Preliminary Report and
Forecast of Solar Geophysical Data", does not show data in it's
"Twenty Seven Day Outlook" past March 31. So any idea of possible
geomagnetic activity after that date will have to come later, say
four or less weeks before your April 30 date. But I will be in
touch and give you the best ideas I can, whether there will be any
geomagnetic disturbance of the polar paths between April 30 and
The discussion above has to do with paths; now let's turn to the
frequencies of interest - 40, 30 and 20 meters. Except for geo-
magnetic disturbances, there will be plenty of ionization to
support propagation of 40 meters. But actual propagation will be
absorption-limited, paths open when in the dark and D-region
absorption at a minimum. So propagation programs like MINIPROP
PLUS or Capman should be looked at for times around 1000-1200 UTC
for possible openings. They will serve you well.
The higher, transition bands, 10.1 MHz and 14.0 MHz, are both
absorption- and MUF-limited. While there might be brief times in
morning hours when the paths would be open, they are more reliable
at the end of the day, as the sun sets and the F-region decays.
For the paths to the USA, that would be 1300-1500 UTC. Check your
favorite propagation program for details.
As for long-path, the problems there are the same as above - paths
across polar caps and all those solar wind problems. Of course,
the greater distances just increase the spatial attenuation and do
nothing to help making contacts. Long-path is not a winning game
in the present circumstances - stations on the Pacific Coast able
to make short-path contacts even with the idea of the "Aluminum
All in all, my advice right now would be to concentrate on short-
path contacts on 40 meters and venture onto 30 and 20 meters at
the end of a day when there will be darkness on the paths.
Without any serious outburst of solar activity, there's little
propect of chances of propagation on 10 and 15 meters. Better to
stay on reliable paths and gratify those of the Deserving that are
For everything you need to know about basic HF radio propagation, you
should pick up a copy of Bob's book, The Little Pistol's Guide to HF
Propagation. It's available for $10 (plus $2 S&H) from Worldradio
Books, P.O. Box 189490, Sacramento CA 95818, U.S.A. Or, for on-line
information regarding radio propagation, check out the propagation links on the N4GN Home Page.
N4GN Home Page | BS7H 1995 Home Page | BS7H 1997 Home Page
Last modified 02 February 1999 by Tim Totten, email@example.com.