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ARRL Propagation Bulletin ARLP037 (2009)

ARLP037 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 37  ARLP037
From Tad Cook, K7RA
Seattle, WA  September 11, 2009
To all radio amateurs 

ARLP037 Propagation de K7RA

No new sunspot activity this week, and no emerging sunspots are
visible on the far side of the Sun.  Sunspot region 1025 (or 11025)
which appeared over August 31 and September 1 faded over a week ago,
and the area in which it appeared has just rotated over the Sun's
western limb.

Average daily solar flux for this week was up slightly, just 0.7
points, to 68.8.  Geomagnetic A indices were quieter, with last
week's average daily planetary and mid-latitude A index at 5.7 and
4.1 respectively, while both numbers dropped to 2.9 for this week.

Very quiet and stable geomagnetic conditions were observed by the
magnetometer used to generate the College A Index at Fairbanks,
Alaska on September 9-10.  From the last reading on September 8
through the end of the UTC day on September 10, the K index was zero
at every 3-hour reading.  It may have continued at that zero-level,
but as of early Friday we have only the data for Thursday.  You can
see it at  For a
longer range view, check

When the term "UTC day" is used in this bulletin, it refers to the
date which ended after 2359z, or UTC.  When it is 2359 UTC (the same
as Greenwich Mean Time, or GMT), Alaska Daylight Savings Time is
1559.  1600 local Alaska time is in the following UTC day, because
it is after midnight in Greenwich.

The planetary A index is projected to be 5 for today through
September 14, then 8 for September 15-18.  Solar flux is expected to
be 69 for today and tomorrow, then 68 for September 13-19.

Geophysical Institute Prague predicts quiet conditions for September
11-12, quiet to unsettled on September 13, 15 and 17, and unsettled
on September 14 and 16.  But Petr Kolman, OK1MGW of the Czech
Propagation Interest Group thinks that September 14 will be quiet,
but September 16 and 26 will be unsettled to active.

The Autumnal Equinox in the Northern Hemisphere is only 11 days
away.  This signals generally improved HF propagation, even with no
solar activity.

As mentioned in past bulletins, even with the quiet Sun, worldwide
propagation is still possible, but at lower frequencies.  Fifteen
and ten meter openings are rare, but 40, 30, 20 and even 17 meters
have the better prospects.

John Parnell, K7HV of Seattle, Washington sent a link to a video he
made while operating with just four watts on a Pacific Coast
backpacking trip last week on Washington State's Olympic Peninsula.
He used a simple radio he built from a kit, and a very basic wire
antenna.  John noted that HF conditions on a trip to the same place
in 2007 were better.  Checking the data in this bulletin from 2007,
August 23-29 had an average daily sunspot number of 12.9, August 30
through September 5 was 16.1, and then for several weeks there were
no sunspots.

Watch the video at and see photos at  Note that in the video you can hear a
snippet of last week's ARRL DX Bulletin transmitted in CW from W1AW.
How do we know this, with just a few seconds of copy?  By comparing
the few received characters to last week's bulletins on the ARRL web

Ronnie Borkgren, NN0L of Anamosa, Iowa writes to say he would like
to see more detail in some of the reports of DX worked.  He wants to
know what power and antennas were used.  We don't mention brand
names very often, but will give details such as "3-element quad" or
"popular 4 element tri-band beam," whether the antenna is homemade
or commercially produced.

Mark Lunday, WD4ELG of Hillsborough, North Carolina gave us enough
detail.  He reported working VK4DHF long path on 20 meter CW on
September 8 at 2130z.  Mark was running just 5 watts and using a
low-slung dipole.

Mark Bell, K3MSB of Airville, Pennsylvania reports he is seeing
better propagation to Southeast Asia in the past week.  He didn't
give his power, antenna or mode, but says "After months upon months
of really awful propagation on 20 meters into the southeast Asia
region, things looked up during the past week."

"I worked 9V1YC (Singapore) on Sept 03 at 0012z, and heard stations
from BY (China) and JT (Mongolia) on at the same time. Last night
Sept 9, I again heard 9V1YC on around the same time, and also worked
9M2MRS (Malaysia) at 0023z. JT stations were also heard on the

"I heard Richard 9M2MRS another night around 0030z but he was too
weak to work."

"Looking back, there seems to (finally) be some nice openings from
the East Coast into the Southeast Asia region around 0030Z the past
few days. Most of the time the signals were not strong, but the QRN
was almost non-existent and they were "weak but workable" as the
saying goes."

Frank Hertel, a consulting broadcast engineer sent an email with his
observations of sporadic-e skip in the summer.  For some reason he
hasn't observed any this year, but of course he isn't trying to
receive weak signals on VHF. His clients become concerned when a
distant signal interferes with their local broadcast.

Frank wrote, "Since part of what I do is to operate a Frequency
Measuring Service for broadcasters, I have a 100 foot tower with
some pretty fair antennas. I also have antennas at about 20 feet
which I use for phase canceling of unwanted signals when required. I
have the assortment of horizontal, vertical and H+V when combined
and phased and level balanced."

"When the interference does happen, the horizontal antennas are most
affected. Often the 100 foot FM band antenna doesn't experience as
much interference reception as my 20 foot high FM band antenna.  The
100 foot antenna never delivers as much signal strength (being
commercial broadband VHF, 40-300 MHz), as does my 20 foot 12 element
FM band antenna, but when the interference does hit, the 100 foot
antenna does a better job (receiving more of a direct signal path
from local signals vs. the interfering signal from above).  On
non-interfering days, the 20 foot antenna actually out-performs the
100 foot FM antenna, since the 100 foot FM antenna, on a normal day,
gets many unwanted signals (150 miles and beyond) that interfere
with the signals I want to measure (100+ miles, and locals)."

"Once in the UHF TV band range, the problem doesn't often happen,
but when it has happened it always seemed to be on very cold and dry
winter nights, when the weather conditions are over a very wide
spread area.  As I can best recall, many years ago my home UHF TV
antenna (15 feet) received Denver Colorado.  I live in Evansville
Indiana, about 1,000 miles from Denver."

"I remember in the 1970's that Havana Cuba had a TV Channel 2.
Every August and September I would disconnect my outside VHF antenna
(to keep from receiving Terre Haute, IN, CH 2) and hook up a pair of
rabbit ears.  Havana Cuba was quite watchable.  I always knew when
Havana was watchable because the reception of CH 2, in Terre Haute,
IN would become quite scrambled. I would see 10 KHZ visual beat, due
to the freq offset of the two carriers."

Very interesting info from a non-ham.  We sent him a link to an APRS
network ( that
automatically reports VHF propagation, and another
( that predicts propagation
via the troposphere.

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

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

Instructions for starting or ending email distribution of this
bulletin are at

Sunspot numbers for September 3 through 9 were 0, 0, 0, 0, 0, 0, and
0 with a mean of 0.  10.7 cm flux was 68.6, 68.4, 68.5, 69.2, 68.8,
68.9, and 69.2 with a mean of 68.8.  Estimated planetary A indices
were 4, 5, 2, 3, 3, 2 and 1 with a mean of 2.9.  Estimated
mid-latitude A indices were 4, 4, 2, 2, 3, 2 and 3 with a mean of


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