Propagation de K7RA

16 February, 2013
ARLP007

Low levels of solar activity continue, the same as the past few weeks. Sunspot numbers remain remarkably consistent, with average daily numbers for the four reporting weeks since January 17 at 56.4, 55.7, 50.7 and finally 51.3 for the past week. As you can see, average daily sunspot numbers rose less than a point from the previous week to the past week. Average daily solar flux receded 2.4 points to 104. Geomagnetic conditions remain calm.

The ARRL International DX CW Contest is this weekend. Conditions will probably be about the same as last year, because solar activity is about the same as this time in 2012. See http://www.arrl.org/arrl-dx for contest details.

The latest prediction for solar flux shows values of 100 for February 15-16, 105 on February 17-19, 100 on February 20-22, 115 on February 23-24, 110 and 105 on February 25-26, 100 on February 27 through March 3, 95 on March 4-9,115 on March 10 and 120 on March 11-13.

The predicted planetary A index is 5 on February 15-20, 9 on February 21-22, 8 on February 23, 5 on February 24-28, then 10 and 8 on March 1-2, and 5 on March 3-17.

Every week F.K. Janda, OK1HH gives us his thoughts on geomagnetic conditions over the next few weeks. Generally for HF propagation, particularly for the higher bands (10-20 meters) we would like to see very little geomagnetic activity, but with as many sunspots and as much solar flux as possible. We have seen a lot of quiet geomagnetic conditions over the past few years, but not much in the way of sunspots or high solar flux values.

OK1HH suggests the geomagnetic field will be quiet to unsettled on February 15-16, quiet on February 17-21, quiet to active February 22, active to disturbed February 23, mostly quiet February 24-25, quiet February 26-28, quiet to unsettled March 1, quiet to active March 2, mostly quiet March 3, quiet to unsettled March 4, quiet March 5-6, mostly quiet March 7-8, quiet March 9, and quiet to active on March 10.

Don't miss the article in the March issue of QST, by Carl Luetzelschwab, K9LA titled "The Sun and the Ionosphere." It begins on page 48, gives an update on Cycle 24, and discusses measuring the Sun and ionosphere and relating solar flux to MUF, or Maximum Usable Frequency.

Neil Shapiro, W2NLS of Bethpage, which is on New York's Long Island, asked about relating the information in these bulletins to practical on-the-air results.

I suggested checking out the resources listed at the bottom of each bulletin, from the ARRL Technical Information Service and also the resources from the K9LA website.

One useful tool is to download the free program W6ELprop (which works on the Windows operating system) from http://www.qsl.net/w6elprop/.

You will need to enter your latitude and longitude for your default station location, and a useful tool for converting street addresses to geographical coordinates is at http://www.latlong.net/convert-address-to-lat-long.html.

You can use an average of the previous 5 days sunspot numbers from here: http://www.swpc.noaa.gov/ftpdir/indices/DSD.txt

For the K index, either use the latest Middle Latitude numbers from here: http://www.swpc.noaa.gov/ftpdir/indices/DGD.txt Or use the planetary number from WWV: http://www.swpc.noaa.gov/ftpdir/latest/wwv.txt

I ran the numbers for Neil on February 15, from his QTH to the Czech Republic. It looks like 15 meters is a good bet from 1430-1700z, 17 meters 1330-1800z, and 20 meters over the same period as 17 meters, but stronger signals on 17 meters (assuming power levels and antennas are equal). It looks like 30 meters should open up around 1800z, and have strongest signals 2130-0100z, and 40 meters 2000-1000z, with best signals around 2230-0630z.

An alternative to sunspot numbers would be to use solar flux. You can set W6ELprop to default to either type, or change it on the fly by entering F103 (for example) as solar flux of 103, or S66 as sunspot number of 66.

The engine used for driving W6ELprop was originally designed to work with the predicted smoothed sunspot number for the month, and it doesn't really work well to try to use the latest day's numbers. So an average for the past 5 days is a compromise.

Another useful tool is a new one from Stu Phillips, K6TU of Woodside, California: http://k6tu.net/. This one is interesting. You subscribe to this service (but I think there is a free trial) and tell it what kind of prediction you want to run, then after making the calculations, it emails a link that you use to display them. For each band, you can step through hour-by-hour to see maps showing where your signals will be strongest, with different colors used to express different signal levels. It is interesting to see how the coverage areas shift, hour-by-hour.

We heard from Peter Thulesen, OX3XR in Nuuk, Greenland. He wrote, "Just to report my observations on 28 MHz propagation from Greenland (grid GP44) to North America, US and VE in the evenings after sunset here in Greenland. Around 2000-2200 UTC I very often have worked several/many stations on 28 MHz CW from all US and VE. This has been the situation January 2013. In the weekends where I have the possibility to monitor the bands during the day 28 MHz seems to be more dead towards W and VE than in the evening just after sunset.

"In the evening after sunset 28 MHz seems dead listening on the band. However, after calling CQ a few times around 28.025 MHz W and VE stations start to answer my call. The signal strength is good up to 599 and stable signals with only little QSB.

"When conditions have dropped for CW contacts I can normally continue working JT65 stations on 28 MHz, maybe another 30-45 minutes. I'm using a sloping dipole toward Europe and 100 watts."

Jeff, N8II of West Virginia wrote: "The seasonal changes we expect on the bands are occurring. Long path propagation has disappeared on 30 meters into SE Asia and the evening openings much improved on 12 thru 20 meters into East Asia. We get JAs some nights in the 2200Z hour on 12, 15 is better and on 20 CW the JTs, JT1AA/3 and JT1E, are much louder around 0100Z along with good openings to UA0U area which were almost nil in mid January.

"Conditions have been quite good at times into central Asia on the low bands. 4S7NE was logged around 0125Z on 40 meters CW on the February 8, T6LG continues to be active on 80 CW and EY8MM was also heard around their sunrise.

"I had quite a struggle completing a QSO with K7EKD near Seattle for his last state on 160 meters due to high noise on his end, but we made it at 0200Z on the February 7."

When Jeff mentioned K7EKD, I thought the call sounded eerily familiar. K7EKD taught electronics in my high school. I spoke with him a few times, but unfortunately was expelled from school (hey, it was the late 1960s!) before I got around to taking any of his classes. At that point I was WA7CSK and had been on the air four years. It was certainly an interesting time to be a teenager.

If you would like to make a comment or have a tip for our readers, mail the author at, k7ra@arrl.net.

For more information concerning radio propagation, see the ARRL Technical Information Service at
http://arrl.org/propagation-of-rf-signals.

For an explanation of the numbers used in this bulletin, see
http://arrl.org/the-sun-the-earth-the-ionosphere.

An archive ofpast propagation bulletins is at
http://arrl.org/w1aw-bulletins-archive-propagation.

Find more good information and tutorials on propagation at
http://myplace.frontier.com/~k9la/.

Monthly propagation charts between four USA regions and twelve
overseas locations are at http://arrl.org/propagation.

Instructions for starting or ending email distribution of ARRL bulletins are at http://arrl.org/bulletins.

Sunspot numbers for February 7 through 13 were 58, 57, 58, 45, 60, 55, and 26, with a mean of 51.3. 10.7 cm flux was 102.8, 104.2, 107.6, 105.9, 105.2, 101.8, and 100.3, with a mean of 104. Estimated planetary A indices were 6, 7, 3, 4, 4, 4, and 11, with a mean of 5.6. Estimated mid-latitude A indices were 7, 8, 3, 3, 3, 3, and 9, with a mean of 5.1.

Source: The American Radio Relay League

• All propagation reports can be found at:
http://www.southgatearc.org/propagation




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