ARRL

ARRL Propagation Bulletin ARLP025 (2006)

SB PROP @ ARL $ARLP025
ARLP025 Propagation de K7RA

ZCZC AP25
QST de W1AW  
Propagation Forecast Bulletin 25  ARLP025
From Tad Cook, K7RA
Seattle, WA  June 23, 2006
To all radio amateurs 

SB PROP ARL ARLP025
ARLP025 Propagation de K7RA

This weekend is the annual ARRL Field Day, so this bulletin will
have a Field Day focus. See
http://www.arrl.org/contests/rules/2006/rules-fd-2006.html for
rules.

One thing nice about the bottom of the solar cycle is disruptive
radio blackouts or sudden ionospheric events are very unlikely,
compared to times when the solar cycle is active. A couple of
decades back I was at a club Field Day site when mid-day Saturday a
solar flare made the bands suddenly so dead that we really thought
our radios were broken. W7RM had just placed a 40 meter bobtail
curtain aimed toward the East Coast over a saltwater path, and I was
convinced it was all for naught. But shortly after, again we heard
signals, and toward the evening K7HBN hooked up to the bobtail and
worked an amazing number of CW stations all night long.

Very low geomagnetic activity is predicted this time around, with
the planetary A index forecast around 5. Sunspot counts for the past
five days have been 23, 21, 20, 19 and 0. No substantial increase is
predicted. Geophysical Institute Prague predicts quiet conditions
June 23, 24 and 27, quiet to unsettled June 25 and 29, and unsettled
June 26 and 28.

I've received many messages asking for advice on which HF bands to
concentrate on. In Field Day, there are no multipliers for states or
sections or countries. What counts for scoring is satisfying rules
for various bonus points and multipliers and working as many
stations as possible on each band and mode. Your best bet is going
to be 40 and 20 meters, and be alert for sporadic-E openings on 15
and 10 meters. 40 meters will be open to many areas of North America
throughout the day and night, and 80 meters should give good results
from a couple of hours before local sunset on Saturday night until a
couple of hours past local sunrise on Sunday morning.

If you are in either California or Georgia, for example, and trying
to work the other end of this path, the best bet for 20 meters is
from 5:30 PM PDT (8:30 PM EDT) until around 6:00 AM PDT (9:00 AM
EDT), then again with moderate signal strength 8:30 AM PDT (11:30 AM
EDT) to 3:30 PM PDT (6:30 PM EDT). In other words, the unlikely
times of making contact from California to Georgia is around
2300-0000z and 1330-1500z.

Rich Klinman, W3RJ in Pennsylvania asks us to remember that with all
the sporadic-E openings on 6 meters, 10 meters has been good as
well. In the morning on 10 meter SSB he has been working Europe, and
he worked the Middle East recently.

Hector Garcia, XE2K mentions that Armando, XE3ARV, around 1530z on
June 16 worked Johan, ON4IQ, running 5 watts to two stacked 4
element Yagis. From the XE3ARV QTH in Felipe Carillo Puerto,
Quintana Roo on the Yucatan Peninsula to Gooik in the Belgian
Flemish Region is about 5,270 miles.

Don't miss the July 2006 QST for an article by Paul Graziani, W5ZK
on using beacon stations to observe band openings and propagation,
followed by some sage advice from Carl Luetzelschwab, K9LA, on when
the bands will improve.

If you would like to make a comment or have a tip for our readers,
email the author at, k7ra@arrl.net.

For more information concerning radio propagation, see the ARRL
Technical Information Service at,
http://www.arrl.org/tis/info/propagation.html. For a detailed
explanation of the numbers used in this bulletin, see
http://www.arrl.org/tis/info/k9la-prop.html. An archive of past
propagation bulletins is at http://www.arrl.org/w1aw/prop/ .

Sunspot numbers for June 15 through 21 were 11, 0, 42, 23, 21, 20
and 19 with a mean of 19.4. 10.7 cm flux was 76.4, 75.3, 73.2, 73.3,
73.3, 72.9, and 72.7, with a mean of 73.9. Estimated planetary A
indices were 28, 10, 10, 8, 5, 4 and 4 with a mean of 9.9. Estimated
mid-latitude A indices were 17, 7, 7, 6, 4, 2 and 2, with a mean of
6.4.
NNNN
/EX