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ARRL Propagation Bulletin ARLP022 (2006)

ARLP022 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 22  ARLP022
From Tad Cook, K7RA
Seattle, WA  June 2, 2006
To all radio amateurs 

ARLP022 Propagation de K7RA

Thanks to Carl Luetzelschwab, K9LA for writing an excellent
propagation bulletin last week while your regular reporter was

Solar activity continues to be low as we head toward the bottom of
the sunspot cycle. Still, we haven't seen weeks on end with no
sunspots, so I suspect the minimum is not quite here.

Let's take a look at the monthly averages of sunspot numbers and
solar flux for May, compared with the past year.

The average daily sunspot numbers for the months May 2005 through
May 2006 were 65.4, 59.8, 68.7, 65.6, 39.2, 13, 32.2, 62.6, 26.7,
5.3, 21.3, 55.2 and 39.6. Average daily solar flux for the same
months was 99.5, 93.7, 96.5, 92.4, 91.9, 76.6, 86.3, 90.8, 83.4,
76.5, 75.5, 88.9 and 80.9.

With fewer sunspots, the higher frequencies aren't as useful. There
is a direct correlation between MUF (Maximum Usable Frequency) and
the number of sunspots. That's why at the peak of a solar cycle 10
meters is much more usable than at the bottom of the cycle.

We received several emails this week about sporadic-E propagation.
This is when unpredictable ionized clouds form in the lower E-layer
of the ionosphere and provide interesting and exciting long range
propagation. June is a very good month for this in the Northern
Hemisphere. Broadcast television DXers such as Mike Shaffer, KA3JAW
in Tampa report regularly receiving TV broadcasts from stations in
Mexico and Central America. Paul Gray, N0JAA in east-central Florida
reports working 12 meter sporadic-E from time to time into Virginia
and New York

6 meters also can be exciting. Bill Van Alstyne, W5WVO of Rio
Rancho, New Mexico writes, "Sporadic-E season is upon us, and
yesterday (Sunday, May 28) saw one of the best 6-meter North
American sporadic-E openings of the past few years. At one point
late Sunday morning, 6 meters was open coast-to-coast, with QSOs
between CA and the east coast via long double-hop propagation (or
maybe triple-hop in some cases) taking place frequently. Here in New
Mexico, I was hearing and working both coasts and pretty much
everything in between with S9+ signals."

Bill continues, "Many stations in the eastern part of the country,
and even out west here, worked a lot of DX in the Caribbean and
Central America, but my path in that direction is poor, and I didn't
hear any of it."

He goes on to say, "I did pick up a number of new grid squares,
though, including EL94 (Florida Keys) on a double-hop path and a
cool backscatter contact with DM34 in central Arizona. Backscatter
is unusual on 6 meter sporadic-E (in my experience). My theory is
that a typical sporadic-E cloud is much more planar a refractive
medium than the F2 layer, and doesn't scatter energy as much in
off-beam directions. Thanks to W7MHW for hearing my weak signal
through the pile-up of S9+20 signals from the southeast states."

Bill continues with, "Heard several guys talking about sporadic-E on
2 meters, but I think it was pretty limited. I didn't hear any
really super-short skip on 6 meters; my guess, from the minimum skip
distances I was hearing, is that the Es MUF was somewhere around
100-120 MHz--at least in these parts."

For the next few days, it looks like solar wind from coronal holes
could be mildly disruptive. The planetary A index forecast for June
2-3 is 20, then settling down to quiet conditions a couple of days
later. Average daily sunspot numbers were up this week over last,
and are expected to rise slightly over the next few days. Higher
sunspot numbers mean higher MUFs, but 20 meters should still be your
best band for reliable worldwide propagation.

For instance, California stations can work Japan on 20 meters
currently around 0600-1600z, while the best 20 meter opening to
Australia should be 0630-1300z. If you are in Georgia, the best 20
meter opening to Europe should be around 2230-0200z and 0430-0830z.

But you can work out your own paths to any location. Just use the
suggestions in an earlier Propagation Forecast Bulletin, ARLP014,
seen on the web at,

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 a detailed
explanation of the numbers used in this bulletin, see, An archive of past
propagation bulletins is at, .

Sunspot numbers for May 25 through 31 were 33, 51, 69, 78, 54, 51
and 44 with a mean of 54.3. 10.7 cm flux was 83.7, 81.6, 83, 84.7,
81.1, 80, and 78.4, with a mean of 81.8. Estimated planetary A
indices were 5, 5, 3, 7, 3, 9 and 6 with a mean of 5.4. Estimated
mid-latitude A indices were 4, 1, 1, 5, 1, 7 and 4, with a mean of


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