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www.southgatearc.org
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Propagation de K7RASolar flux and sunspot numbers were up a bit this week, with the average daily sunspot number rising 25 points to 33.6. Friday, August 11 had a daily sunspot number of 39. With more sunspots, the higher HF bands have better propagation than they did nearly two weeks ago when the sunspot number was zero on four days in a row. A coronal mass ejection from the sun was pushed out on August 16. The result could be geomagnetic disturbances this weekend. The predicted planetary A index for August 18-21 is 10, 25, 15 and 8. We are still anticipating the upcoming solar minimum, but a large amount
of email arrived this week with the news of the first spot of cycle 24.
It only appeared briefly, then disappeared. The clue was the magnetic
polarity of the spot, opposite of sunspots from the current cycle 23.
As time goes on, there will be more cycle 24 spots, and eventually fewer
cycle 23 spots. See the announcement at The extra propagation bulletin earlier this week (see After sifting through it all, some of it from retired military or defense engineers familiar with the VLF transmitters mentioned by Dr. Rodger, it may be that Ward Silver, N0AX had the right idea when he wondered how it could be done, when ''the sheer energy required from the start would tend to rule it out''. When Dr. Rodger said that ''two of the US Navy transmitters radiate 1 megawatt'', he probably didn't realize that this is the input power (before inefficiencies are factored in) to the transmitter, and doesn't reflect the efficiency of the antenna. David Olsen, W6PSS pointed out that a 2-megawatt Navy VLF transmitter in Michigan only radiates 1 watt, and the efficiency is around .00005%. He wrote, ''As I understand it, the limitation in achieving efficiency is the coupling factor. As the operating frequency is lowered, there's an exponential increase in reactances such that it becomes nearly impossible to couple energy to an antenna.'' Ed Bruette, N7NVP mentioned an article about a more efficient VLF antenna at http://coldwar-c4i.net/VLF/design.html, but Ed is also skeptical of the article about Dr. Rodger. Don Rice, AC7ZB wrote, ''. . . the radiation belts have to be ''Scientists have been poking the ionosphere for many decades trying to get it to do something, and short of setting off an ionospheric nuclear explosion forty some years ago they haven't had much success''. ''From the amateur radio standpoint, I think the greatest threat is that hams will get cranked up and make statements that will get us branded as a bunch of alarmist loonies. That could be very damaging to our efforts to curb BPL and other spectrum pollution''. John Kelley, K4WY wrote (from his wireless pager), ''. . . space is a big place, to shield the LEO birds with this technique would require incredible energy levels over a global spectra of satellites at varying orbits and ephemeris. I think of the Northern lights as an example of energy and ionized particles that at its peak can only cover upper/mid latitudes. Our current and near term future technologies are still wrestling with
IP in space environments, autonomous control, investigating things like
how to maintain a human presence on the moon, so when taken in that perspective
I 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, see the ARRL Technical
Information Service at For a detailed explanation of the numbers used in this bulletin, see An archive of past propagation bulletins is at http://www.arrl.org/w1aw/prop/ . Sunspot numbers for August 10 through 16 were 37, 39, 27, 26, 45, 32 and 29 with a mean of 33.6. 10.7 cm flux was 80.3, 83.9, 84.7, 85.9, 86.4, 85.6, and 86, with a mean of 84.7. Estimated planetary A indices were 5, 6, 8, 2, 4, 3 and 3 with a mean of 4.4. Estimated mid-latitude A indices were 4, 3, 4, 2, 2, 2 and 2, with a mean of 2.7.
Source: The American Radio Relay League
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