Propagation de Tad Cook K7RA

As we cruise into the low part of solar cycle 23, the sun has been very quiet, save for some coronal holes providing solar wind streams.

This week average daily sunspot numbers were up nearly ten
points compared to last. The geomagnetic field has been mostly quiet, although a little more active than the previous week.

Over the next week expect solar flux to stay around 90, with
geomagnetic conditions quiet, except for some unsettled to active conditions around January 23-24. Geophysical Institute Prague expects quiet conditions January 21, quiet to unsettled January 20 and 22, unsettled January 25 and 26, unsettled to active January 23, and active conditions (higher A and K index) on January 24.

Rich DiDonna, NN3W of Virginia writes that, "While conditions on the high bands may stink, conditions on the low bands have been spectacular. 40 meters is opening to Europe as early as 2100z from the East Coast with reliable openings to the Middle East, and long path to Southeast Asia. 80 and 160 have also been amazing. So, while Old Sol may be in "nap" phase, one should not assume that there is a lack of DX to work!"

Jon Jones, N0JK of Kansas echoes Rich's comments about the lower frequencies in a January 14 email. He writes, "160 meter propagation to Europe from the Midwest and western USA is picking up. For a low band propagation beacon I listen to the 1.2 megawatt AM station from Kvitsoy, Norway on 1314 kHz. Its signal has been very strong the last couple of evenings. Great 160M conditions were noted by W8CAR and others the same time to Europe."

Jon also noted an extensive 6 meter E layer opening on January 13-14 in which W1, W2, W3 and W4 stations were coming in.

Charles Lewis, S9SS of Sao Tome and Principe (an African island in the Atlantic Ocean about 150 miles west of Libreville, Gabon) was one of the stations reported in a recent bulletin by K7HP in Arizona as worked on 10 meters. Charles writes, "The reason Hank worked me that night is that I also use propagation beacons. On 10 meters, I
primarily depend on the W3VD beacon in Laurel, MD. That evening, as I often do, I had the receiver tuned to the W3VD beacon while I worked at the computer across the room. About 2110z I heard the beacon rise dramatically out of the noise. I checked and found the band was becoming live with 10 meters stations. I fired up my amp and called CQ. In a period of about 40 minutes I worked about 40 stations. I would have worked many more, but it took a while of rag
chewing before I was discovered by the crowd."

He continues, "These late 10 meters openings are not very unusual for me in the 2015 to 2130z time frame. They more often start around 2030 to 2040z. They might last a few minutes or they might last a couple of hours. Until early last year, they were nearly nightly. Now they are a lot more scarce. There have been many times that I heard W3VD with a good signal and could raise no one or perhaps had a long rag chew with someone followed by no takers afterward."

Charles goes on to say, "I also had a very good opening on 12/11, the second day of the ARRL 10 Meters Contest that began about 2010z. I worked about 115 contacts coast to coast in NA over a period of about 50 minutes until it died. In that case also, I was working at the computer and heard W3VD pop out of the noise. The band usually dies about as suddenly as it comes to life."

He continues, "I am only about 20 miles north of the Equator. There is only about a 20 minute variation in sunset time over the year. The sun is usually down well before 1800z, so these openings are long after my sunset".

Charles says that on 20 through 12 meters he uses the IARU beacon system, and on 12 meters he often hears 4U1UN in NYC coming in strong, while no one else seems to be on the band. He says 20 meters is his best band for working the USA, and is the best way to communicate with friends near his vacation home in Western North Carolina.

Charles has an interesting challenge operating from his QTH, and that is from a huge Voice of America transmitter site that seems to hover over his station in a photo he sent. Check out a similar image on the web at, http://groups.msn.com/s9ss.

A couple of weeks ago Carl Luetzelschwab, K9LA had some comments about SSNe, or Effective Sunspot Numbers, and the T-Index. He continues with more comments below, through the end of this bulletin.

Carl begins, "In the January 6 Bulletin, I said the T Index and SSNe were similar methods that give a better picture of what the ionosphere is doing "now." Both represent an effective sunspot number based on real-time sounding of the F2 region critical frequency. Let's look at the basic difference between SSNe and the T Index.

"SSNe is calculated from a worldwide set of ionosondes at
geomagnetic latitudes lower than 50 degrees. The SSNe plot also shows the RMS % difference between the foF2 values used to derive SSNe and foF2 calculated from the model using that SSNe as input. This parameter typically runs about 20% or so - if it exceeds 30% this indicates that the global ionosphere is departing more from the model expectation than usual. And if it exceeds 50%, buyer beware!

"The T Index is calculated from 14 ionosondes in the Australian sector. The regional maps (Australasia, Europe, and North America) show the difference between the predicted monthly T Index (which is in tabular format at www.ips.gov.au/HF_Systems/6/4/1) and the current observed hourly conditions in the desired region.

"Which one is best to use? That's a tough call, but I'd personally give the edge to SSNe for global predictions as it is based on worldwide data.

"To reiterate from the January 6 Bulletin, neither gives us a daily model of the ionosphere. But both do allow you to assess whether the current conditions are generally equal to, better than, or worse than the median value from your propagation prediction program when using the heavily averaged smoothed sunspot number (or smoothed solar flux).

"Thanks to Jim Secan of Northwest Research Associates in Tucson for information on SSNe and for forwarding the T Index information from Garth Patterson at IPS."

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

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,
http://www.arrl.org/tis/info/propagation.html. An archive of past propagation bulletins is found at, http://www.arrl.org/w1aw/prop/.

Sunspot numbers for January 12 through 18 were 12, 0, 0, 32, 42, 36 and 50 with a mean of 24.6. 10.7 cm flux was 76.5, 76.5, 77.4, 80.9, 83.8, 82.5, and 85.6, with a mean of 80.5. Estimated planetary A indices were 3, 2, 3, 4, 14, 8 and 5 with a mean of 5.6. Estimated mid-latitude A indices were 2, 4, 2, 4, 8, 10 and 9, with a mean of 5.6.

Source: The American Radio Relay League

Latest news stories..

• Get our news headlines for your website • Submit your news story