Propagation de K7RA

20:54 Fernando Luiz de Souza 0 Comments

13 October, 2012
ARLP041



Another decline in sunspot activity this week, but based on activity over the past few days and projected solar flux values it is making a steady recovery.
Average daily sunspot numbers dropped from 73 to 51.7, a difference of 21.3 points. But the past three days saw sunspot numbers higher (63, 71 and 82) than the average, and climbing.
The average of daily solar flux was off 23.8 points to 104.9, and like the sunspot figures, the past three days saw solar flux values (106.2, 112 and 116.6) higher than the average for the week, a good indicator of the rising activity.
Predicted solar flux from the Thursday, October 11 NOAA/USAF forecast is 115 on October 12-13, 120 on October 14-17, then 125, 130, 150 and 145 on October 18-21, 140 on October 22-23, 135 on October 24-27 and 130, 125, 120 and 115 through the last day of October. Solar flux is then predicted to dip below 100 on November 4-8 and peak at 145, 150 and 145 on November 15-17.
October 12-17 predicted planetary A index is 5, 5, 12, 12, 10 and 8, then 5 on October 18 through November 3, then 18, 20, 12 and 8 on November 4-7, 5 on November 8-10, then 8, 12 and 10 on November 11-13 and 5 after that, through the end of the 45 day forecast period.
We always get a bit different perspective on upcoming geomagnetic conditions from OK1HH. He predicts quiet to active conditions October 12, quiet to unsettled October 13, quiet on October 14, quiet to unsettled October 15, quiet October 16, quiet to active October 17, quiet to unsettled October 18-19, quiet on October 20-22, quiet to active October 23, quiet October 24-27, active to disturbed October 28, mostly quiet October 29-30, quiet October 31 and November 1, quiet to active November 2, and mostly quiet November 3.
October 8-9 showed the most geomagnetic activity during the past week, with planetary A index at 35 and 42, mid-latitude A index at 21 and 32, and the high latitude college A index at 66 and 54. This activity was triggered by a coronal mass ejection on October 8. The predicted rise in planetary A index to 12 on October 14-15 is because of a solar wind spewing from a coronal hole, which should rotate into a geo-effective position during that time.
John King, EI2HVB said on October 10 he worked W1AW in Newington, CT on 20 meter CW using only 2 watts into a sloping V dipole from an MFJ Cub transceiver. This was right after seeing aurora from his QTH for several nights in a row. Of course, unlike here on the West Coast, a path from W1AW to Ireland is not anything near a polar route, so it would not be as affected by geomagnetic unrest as a contact to Europe from the West Coast would be. In Seattle, my bearing to Letterkenny, John's QTH, would be 35.7 degrees, close to the auroral zone, and his return path would be at 316.9 degrees.
But from W1AW short path would be toward 49.2 degrees, and return path is 280.4, further away from the polar path.
Dean Lewis, W9WGV of Palatine, Illinois wrote: "While working county after county in the California QSO Party on the low end of 10 meters on Saturday, October 6, I heard PY2XC calling CQ DX. Had a friendly exchange with Carlos; 559 signals both ways, no QSB. He was running 200W to a dipole; due to outside antenna restrictions I run an Icom 703 (10W max) into an end-fed 65 foot wire (half wave on 40 meters) indoors along the upstairs ceiling (I've had the most supportive XYL in hamdom for 42 yrs). It resonates at a low SWR on 40, 20, 15, and 10 meters without a tuner. QRZ.com says the distance is 5,248 miles from my QTH (25 miles NW of Chicago). A half hour later his signal was S9+."
I received some interesting emails this week from a ham who has one of those FCC experimental licenses that allows him to operate below the AM broadcast band to test antennas, radios and propagation. I was about to present some of his observations here in the bulletin, but just now noticed that at the very top of his first email was a statement about "this is not intended for publication." That's unfortunate, as he wants to attract others to do what he is doing, but now I feel restrained from quoting our correspondence. If you send me an email, normally you can assume that I might quote you as well as make edits for brevity and readability.
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 October 4 through 10 were 56, 55, 39, 37, 41, 63, and 71, with a mean of 51.7. 10.7 cm flux was 109.5, 106.2, 98.8, 98.1, 103.4, 106.2, and 112, with a mean of 104.9. Estimated planetary A indices were 3, 4, 6, 5, 35, 42, and 10, with a mean of 15. Estimated mid-latitude A indices were 3, 3, 5, 4, 21, 32, and 6, with a mean of 10.6.

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