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ARRL Propagation Bulletin ARLP029 (2010)

ARLP029 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 29  ARLP029
From Tad Cook, K7RA
Seattle, WA  July 23, 2010
To all radio amateurs 

ARLP029 Propagation de K7RA

Sunspot activity increased recently, although it is foolish to call
this a trend because solar activity has great variability.  Sunspot
group 1087 was visible for 13 days over July 9-21.  In millionths of
a solar hemisphere, its size was 30, 100, 120, 130, 70, 100, 60, 50,
20, 10, 10, 10, and 10.  On July 19 new sunspot group 1089 appeared
over the eastern horizon, with a relative size of 130, 150, 310 and
240 for July 19-22.

Predicted solar flux for July 23-25 is 88, 85 on July 26-30, and 83
on July 31.  This is fairly strong, considering that the average
daily solar flux for each of the past four weeks was 73.9, 72.8,
79.2 and 80.6.  There is a small predicted rise in geomagnetic
activity, with a predicted planetary A index from July 23-31 of 10,
10, 8, 8, 10, 7, 7, 5 and 5.

Geophysical Institute Prague predicts unsettled conditions on July
23, quiet to unsettled July 24, unsettled July 25-26, unsettled to
active July 27, and unsettled July 28-29.

Perhaps another sign of a quiet sun, which includes a weakening
solar wind, is the collapse of the Earth's thermosphere.  Marcia
Stockton, NU6N, who lives off the grid on a wilderness ranch
northeast of Bakersfield, California at elevation 4,500 feet, shared
with us an interesting article from NASA.  Titled "A Puzzling
Collapse of Earth's Upper Atmosphere", you can read it at

Kurt Kochendarfer, KE7KUS of Phoenix, Arizona sent in a report last
week just a few hours late for bulletin ARLP028.  He reports, "The
evenings of 11 and 12 July I was working 20m PSK-31 around 14.070
and saw strong openings into central European Russia from my QTH in
Phoenix, AZ which began around 0330Z and lasted approximately an
hour on each night.  With a minimal antenna setup (275 foot long
horizontal loop mounted on top a block fence up about 6 feet) and
50W I worked UR8MH, UA3PT, RZ3DC, and RA3FO in a period of 20
minutes beginning at 0340Z on 11 July.  Numerous other Russian and
Ukrainian stations were heard, but I was unsuccessful breaking
through the mini-pileups.  This was a real treat, as I usually have
a hard time working that far east in Europe with my antenna setup".

"I suspect the gray-line may have had something to do with the
propagation, and it made for an enjoyable couple of hours to add
some new European DX to the logbook.  Summer evening DX on 20m has
been relatively good here in Phoenix, of late as well.  In the last
month I've had success working FO8RZ in Tahiti, and heard a number
of South Pacific stations from New Caledonia all the way to central

"While the solar numbers aren't anything remarkable, the relatively
quiet conditions combined with my loop antenna have made for lots of
new contacts in the logbook".

Thanks, Kurt.  That low antenna sounds like a good NVIS aerial for
75-80 meters.  NVIS, for those who don't know, stands for Near
Vertical Incidence Skywave.  The concept involves an antenna close
to the ground with a high angle of radiation.  That is supposed to
provide better regional coverage on the low bands than a low-angle
radiator does because the radiation going up refracts back to a more
immediate area.  Assuming that 1005 divided by MHz is a good formula
for calculating dimensions of a full-wave loop, then the reciprocal
suggests a frequency of 3.655 MHz.

Mike Majority, N4VBV of Sumter, South Carolina mentions that beacons
on the ten meter band are useful for detecting openings, even when
no live hams are on the air.  His page at gives some beacon info and resources,
and he suggests W5JO as a good source of data.  W5JO has a beacon
list for 10 meters at  It is also
worth mentioning the Northern California DX Foundation and their
sophisticated networks of beacons on 20, 17, 15, 12 and 10 meters.
See info on their web site at

Jim Fenstermaker, K9JF lives in the Ballard neighborhood in Seattle,
but has a station in Vancouver, Washington (not to be confused with
the VE7 Vancouver) near Portland, Oregon.  He writes, "The opening
on 20 on Saturday evening and Sunday morning was fantastic during
the IARU Contest, the best I have seen for many years.  By 0000Z on
Saturday, I worked one (1) WRTC station and in the evening I was
able to add another 37 or so.  Overall, my low power entry totaled
953 Q's.  I operated from the Vancouver QTH which allowed for the
antennas to play and the neighbors to be spared from large amounts
of RF in their stereos.  But, all the locals worked stations over me
as they were high power entries.  I now have the view that both QRP
and Low Power is not for sissies.  And, I have not sat in the chair
for 24 straight hours for years either".

Robert Elek, W3HKK of Johnstown, Ohio writes this about six meter
signals last weekend:  "During this weekend's VHF Test, I noticed
numerous bursts of signals in the S-5 range, about a half syllable
long, and then the signal was gone or just tickling the noise level
at S1.  It happened a few dozen times.  Am I hearing meteor burst
propagation or momentary ducting, or??"

"I also heard numerous weak signals from 100-500 miles out that
would slowly build up to S2 (Q5) for a few minutes and then fade
down into the noise.  This happened over and over with the same
station, typically around 8-10 am.  What is the most likely cause of

"Test conditions were punk with only a couple of signals from CO,
TX, etc, and a few from around 300-400 miles out but very weak.
Most were from Ohio about 50-150 miles away".

Don't forget to check the latest issue of WorldRadio magazine, free
online on the twentieth of each month.  Each issue has a propagation
column from Carl Luetzelschwab, K9LA, and this month Carl also has
an article noting the passing of Bob Brown, NM7M.  Read it at  In Carl's column in the current
issue (August 2010) he reviews the N6BV Propagation Predictions.

If you would like to make a comment or have a tip for our readers,
email the author at,

For more information concerning radio propagation, see the ARRL
Technical Information Service at  For an explanation of the
numbers used in this bulletin, see  An archive of past
propagation bulletins is at  Find more good
information and tutorials on propagation at

Monthly propagation charts between four USA regions and twelve
overseas locations are at

Instructions for starting or ending email distribution of ARRL
bulletins are at

Sunspot numbers for July 15 through 21 were 15, 17, 13, 12, 25, 32,
and 38 with a mean of 21.7.  10.7 cm flux was 75.9, 76.6, 78.7,
76.9, 79.8, 87 and 89.1 with a mean of 80.6.  Estimated planetary A
indices were 10, 4, 2, 3, 4, 5 and 5 with a mean of 4.7.  Estimated
mid-latitude A indices were 10, 2, 1, 2, 2, 3 and 3 with a mean of


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