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ARRL Propagation Bulletin ARLP035 (2005)

ARLP035 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 35  ARLP035
From Tad Cook, K7RA
Seattle, WA  August 19, 2005
To all radio amateurs 

ARLP035 Propagation de K7RA

Thanks to Carl Luetzelschwab, K9LA, for filling in for me last week
with one of his excellent bulletins.  My wife surprised me with
tickets to a Bruce Springsteen concert on Thursday night, which is
when I normally write the bulletin.

Not much solar activity occurred over the past week.  A few days ago
Earth entered a solar wind stream which raised geomagnetic activity,
but not to the level of a storm.

Sunspot numbers and solar flux are expected to remain low, but rise
moderately again around August 26 through the end of the month.
Geomagnetic conditions should stay mild, with unsettled conditions
returning around August 23-26.

Frank Donovan, W3LPL of Glenwood, Maryland sent in some interesting
web links regarding six meters and sporadic-E propagation.  The
links are and  On the link, the dates
may be a bit confusing, because the title says the graph covers the
period from 1995 to present, but the dates along the x-axis run from
early May to the present.  This graph shows cumulative activity
during May through August over the past decade, so the data isn't
just from this year.  It illustrates when sporadic-E propagation
across the Atlantic is the most common, in late June and early July.

We get reports of TV and FM DX during sporadic-E season, and
sometimes mention them in the bulletin.  Doug Allen, W0AH of
Woodland Park, Colorado wrote to say that receiving FM and TV
stations from over 1000 miles away via sporadic-E propagation is
fairly common in the summer.  He has personally logged over 3,000 FM
broadcast stations via sporadic-E skip, and a few hundred of those
were at 1450-1500 mile distance.

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

Sunspot numbers for August 11 through 17 were 35, 47, 33, 34, 49, 48
and 42 with a mean of 41.1. 10.7 cm flux was 75.9, 76.2, 75.4, 74.8,
75.8, 75.8 and 77, with a mean of 75.8. Estimated planetary A
indices were 6, 6, 16, 10, 8, 19 and 18 with a mean of 11.9.
Estimated mid-latitude A indices were 2, 3, 14, 6, 6, 12 and 11,
with a mean of 7.7.


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