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ARRL Propagation Bulletin ARLP028 (2011)

ARLP028 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 28  ARLP028
From Tad Cook, K7RA
Seattle, WA  July 15, 2011
To all radio amateurs 

ARLP028 Propagation de K7RA

Average daily sunspot numbers this week were up 57 percent over the
previous seven days, rising from 41.6 to 65.6.  Average daily solar
flux rose just 3 points to 89.1.
There seem to be plenty of sunspots of late, but none have been
large, and so the sunspot number and solar flux are not as high as
in some previous months.
A new sunspot appeared on July 7, then three the next day on July 8,
then a new one each day on July 9, 10 and 11, and two more on July
13 and another two on July 14.  A coronal mass ejection on July 9
gave us some geomagnetic activity a couple of days later.
The current forecast shows the planetary A index on July 15-24 at 5,
5, 5, 8, 8, 12, 12, 8, 8 and 5.  Solar flux is predicted at 94 on
July 15-17, 92 on July 18-19, 90 on July 20-21, then 94, 90, 89, 87,
87, 89 and 88 on July 22-28.
Geophysical Institute Prague says look for quiet to unsettled
geomagnetic conditions on July 15, quiet July 16-17, unsettled July
18, unsettled to active July 19, unsettled July 20 and quiet to
unsettled July 21.
Jeff Hartley, N8II of Shepherdstown, West Virginia sent in a report
on recent 6 meter activity.  He wrote, "The recent somewhat lower
solar flux is noticeable on the bands, late night openings to EU on
15 are curtailed and 17 meters is slow to open to anywhere in our
"I got up late today, July 8 to find a very good 6 meter opening to
Europe.  The first station heard was DK1DAX who rapidly faded down
followed by EA7KW (who is always there when the band is open), then
G8BCG who I managed to work.  Then the Mediterranean area really
started to come thru well around 1435z.  IS0GQX, F5PAU, CT1DVV,
CT1EWX, EA7RM, another F5, and ZB2FK (Gibraltar) was worked for a
new country."
"On Sunday July 3 I finally logged PJ6D around 2300z after hearing
them on FD for quite a stretch, but my weak signal could not be
heard there".
"Around June 29, SM5EDX was the only signal heard on 6 meters at
2115z besides a few direct signals on the East Coast calling him.
There have been quite a few 6 meter European openings into W1, W2,
southern W4 and the Midwest that did not extend into my area".
Thanks, Jeff!
Robert Elek, W3HKK of Johnstown, Ohio writes "Thursday July 7 around
2300z saw a nice 6 meter opening to Portugal with three strong (57
to 59) signals arriving in central Ohio from CT1's HZE/HZJ/FFU.
Signals were in and out for several hours centered on 2300z.  Nice
going guys!  Have a glass of Porto on me!"
"Then on Friday morning, July 8, it hit the fan in central Ohio!  I
worked CT1FFU and HZE again, stronger than the night before, and
then witnessed nearly all of western Europe coming thru, one by one,
building up out of the noise to around 55/559 and sometimes as in
the case of IS0GQX up to 59.  It seemed GQX was in there from around
1300z until the band quieted down around 1800z.  Kudos for an
amazing signal!  Meanwhile, I had fun working F8DBF, ON5HJS, 9H1BT,
EA7KW, all new countries for me, and a couple of Canadian
Maritimers.  But alas, the hoped for evening opening didn't
materialize in central Ohio, although I saw the Euro's were still on
but working 6's and 7's and 5's".
"Imagine all this DX with 100 watts to a 5 element Yagi towering TEN
FEET above the rear patio, 'equipped' with an Armstrong rotator!  
Six is indeed The Magic Band.  This was the most widespread DX
opening I have seen in my two years on the band.  I heard stations
from England, Italy, and Russia as well.  Very cool opening!"
Thanks, Robert.  As the kids say, "Awesome!"
We get a lot of email about solar activity, including some from
non-hams curious about something they read in the news.  Some people
mention that in the same week they see articles claiming we're in
for some sort of dangerous solar maximum, but then they read about a
dearth of sunspots.  I ran across this at a NASA site, which reminds
me of some of the questions I get:

Another interesting piece is this one about a big solar event 11
years ago:
Pat Moore, AL7L of Juneau, Alaska pointed out that perhaps the use
of the word "millennia" in the last bulletin was unintended, as
"millennia" is plural, while "millennium" is singular.
Dick Bingham, W7WKR, who used to live in my Seattle neighborhood now
lives way off the grid at Stehekin, Washington, reachable only by
boat or a very rugged mountain trail.  Check out his interesting
address in the lookup feature at or at
Dick sent an article and video from NASA about a dark solar
explosion that continues to baffle and fascinate over a month after
the event.  See and read about it at
Mike Schaffer, KA3JAW loves to DX TV and FM broadcasts in Tampa,
Florida, and reports some intense sporadic E propagation on July
11-12.  He writes, "On Monday, July 11 at 2310 UTC I was getting
traces of B/W video with occasional audio from a unidentified
Canadian TV-6 broadcaster via Sporadic-E that continued up until
0235 UTC (9:35 pm EDT)".
"I do not recall ever having Es all the way up on channel 6 (83.25
MHz video/87.75 MHz audio) this late in the evening from Canada".

"The next day, during the 1730 UTC time I heard one unidentified
Cuban TV-6 audio on 87.7 on the car radio.  Five minutes later I
tuned up to 107.7 with a reception of an unidentified Mexican
station.  Both stations had fluctuating signal strengths from
moderate to strong with a slow rate of fading".
"While remaining on 107.7 for the next hour I heard an advertisement
for the website for about one minute, then fading away.
Twenty-minutes later the signal came in with a moderate signal
strength at the best possible time giving its identification spot,
'107-7 The Bay'".
"The reception distance was 1,191 air miles from Alpena, Michigan to
Tampa, Florida.  That would place the Es plasma cloud overhead of
Rogersville, Tennessee".
Mike got a confirmation from the manager of the broadcast station
that indeed he had received WHSB on 107.7 MHz.  Mike mentioned that
he received the signal using the back-side of a cross-phased
multi-element antenna.
Joe Miller, KJ8O of Troy, Michigan writes about some curious
propagation he experienced. "For the past five years, I have worked
the IARU Championship and/or Field Day, and I have worked stations
on 20 meters that are in the 200-300 mile range as opposed to the
usual 600-700 mile or further first skip.  I have noticed this short
propagation only occurs in late June and early July.  The big
surprise for me this year was working AC8G in Dayton OH at 1515z on
Saturday, July 7 on the 15 meter band at a distance of 212 miles.  I
contacted him and he stated that he was using a tower of about 62
feet and a four element Yagi pointed towards Europe and running
about 900 watts.  On my end, I have a 5BTV and was running 100
watts.  His was a good solid signal, not the kind usually heard by
backscatter".  Joe wonders what was happening to enable this

We ran this by Carl Luetzelschwab, K9LA, who wrote "The time period
suggests sporadic E".

"We normally think of sporadic E on 6 meters and even on 10 meters.
We usually don't think of sporadic E extending down to the lower
frequencies.  But if the electron density is high enough to refract
6 meters, then it's high enough to refract lower frequencies like 15
meters and 20 meters".
"The limiting factor determining the effect of sporadic E on these
lower frequencies is the thickness and extent of the sporadic E
cloud.  It has to be thick enough and wide enough (at least several
wavelengths) to allow a gradual bending (refraction) to occur.  More
than likely the thickness is the true critical parameter.  Perhaps
the thickness and extent was sufficient to allow short skip on 15
meters on your path.  And with enough electrons to refract 50 MHz (I
saw many 6 meter spots over the weekend), it's also possible that
reflection could have been involved on 15 meters, which says the
cloud would not have to be as thick nor as wide".
Carl looked at the Millstone Hill (Massachusetts) ionogram for July
7 at 1515 UTC.  "Of course it's not near Joe's path, but it's the
closest we have!  Note that sporadic E was occurring, and the
ordinary wave sporadic E critical frequency was reported as 4.28 MHz
and the extraordinary wave sporadic E critical frequency (the green
echoes at the same virtual height) was up to 5 MHz.  These critical
frequencies couldn't support high-angle 15 meter propagation, but we
just don't know the magnitude and extent of sporadic E on Joe's
specific path.  All we can say is sporadic E was occurring in
Massachusetts, and 6 meter spots suggest it was also occurring
"Other possibilities are an F region anomaly, but not too likely as
the summer months are generally quiet and have the lowest F region
electron densities (for what it's worth, the sparse Millstone Hill
data says high-angle F region propagation over your path couldn't be
supported, either).  As for a geomagnetic disturbance as suggested
by your friend, I see that the A and K indices were not elevated on
July 7, so that would be tough to couple to your QSO.  Another
possibility could be extremely long ground wave (I can easily work
Toledo and Dayton on 15 meters from Ft Wayne) but the signals would
be weak.  A last possibility would be some kind of scatter mode, but
again with weak signals".

Thanks, Carl.  Great analysis!

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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
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Monthly propagation charts between four USA regions and twelve
overseas locations are at
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bulletins are at
Sunspot numbers for July 7 through 13 were 42, 65, 55, 67, 72, 62,
and 96, with a mean of 65.6.  10.7 cm flux was 85.5, 85.8, 85.6,
90.7, 90.1, 91.7, and 94.6, with a mean of 89.1.  Estimated
planetary A indices were 6, 8, 12, 12, 13, 8, and 8, with a mean of
9.6.  Estimated mid-latitude A indices were 6, 6, 10, 8, 10, 7, and
6, with a mean of 7.6.


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