Page last updated on: Saturday, April 20, 2013 Propagation de K7RA 20 April, 2013ARLP016 Solar activity weakened over the current reporting period (April 11-17), and geomagnetic conditions were stable as well. The predicted geomagnetic storm did not happen last weekend, with both the planetary and mid-latitude A index only rising to 10 on Sunday April 14 in response to a glancing blow from a CME. Average daily sunspot numbers declined nearly 25 points to 113.3, and average daily solar flux was down over 17 points to 121.7. Predicted flux values for the near term are 95 on April 19, 90 on April 20-23, 95 on April 24-25, 100 on April 26, 110 on April 27-28, 115 on April 29-30, 120 on May 1-2, 125 on May 3-6, 120 on May 7-8, and 115 on May 9-12. Predicted planetary A index is 5 on April 19-22, 12 on April 23-25, 15 on April 26, 5 on April 27 to May 4, 8 on May 5, 5 on May 6-11, and 8 on May 12. F.K. Janda, OK1HH of the Czech Propagation Interest Group predicts the geomagnetic field will be quiet to unsettled April 19, quiet April 20, mostly quiet April 21, quiet to unsettled April 22, quiet to active April 23, active to disturbed April 24, quiet to active April 25, active to disturbed April 26, quiet to unsettled April 27-28, mostly quiet April 29-30, quiet May 1-4, mostly quiet May 5, quiet May 6-7, mostly quiet May 8, quiet May 9, mostly quiet May 10, quiet to unsettled May 11-12, and mostly quiet May 13. Carl Luetzelschwab, K9LA maintains a great website devoted to propagation information, but it moved recently to a new domain. Check http://k9la.us/. Paul Drahn, KD7HB of Crooked River Ranch in Central Oregon wrote: "I must take exception to your comment about 'great news for HF propagation.' It's very difficult for local evening nets on 75 meters. I am active on the Oregon Emergency Net on 3980 from 6pm to 7pm. Just prior to our net, the Tennessee phone net operates on the same frequency. Afterward, several Tennessee hams use the frequency as a local rag chew net. At times, like the last two evenings, they are stronger in Oregon than many of the local check-in stations. Last night there were at least three conversations going on from Tennessee, all on 3980. They could not hear each other, and could not hear the OEN. "We expect this interference in the Winter, but only is a problem at other times when the propagation allows it. Fortunately the folks in Tennessee go to bed early!" As we move later in the Spring and toward Summer, the signals should be weaker around net time. It might help if the folks in Tennessee used NVIS type antennas for local coverage, as they don't have a low angle of radiation. There are several pages that describe the NVIS, or Near Vertical Incident Skywave antenna, such as http://www.hamuniverse.com/nvisbeam.html or http://www.w0ipl.net/ECom/NVIS/nvis.htm or https://www.txarmymars.org/downloads/NVIS-Antenna-Theory-and-Design.pdf. 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 of past propagation bulletins is at http://arrl.org/w1aw-bulletins-archive-propagation. 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 April 11 through 17 were 121, 128, 148, 111, 99, 97, and 89, with a mean of 113.3. 10.7 cm flux was 137.1, 137.9, 125.1, 116.8, 113.3, 113.3, and 108.1, with a mean of 121.7. Estimated planetary A indices were 5, 5, 6, 10, 5, 3, and 3, with a mean of 5.3. Estimated mid-latitude A indices were 4, 4, 6, 10, 6, 2, and 2, with a mean of 4.9. Source: The American Radio Relay League • All propagation reports can be found at: http://www.southgatearc.org/propagat