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www.southgatearc.org
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Propagation de K7RAThis is a special early edition of the propagation bulletin, three days before the regular Friday publication schedule. The regular bulletin will appear on Friday, August 18. A newspaper article on Monday out of New Zealand reported a proposed Defense Advanced Research Projects Agency (DARPA) project that could cause major worldwide disruptions to HF radio communication and GPS navigation. The ''Radiation Belt Remediation'' (RBR) system is envisaged as a method for protecting low earth orbit (LEO) satellites from damage caused by high altitude nuclear detonations or severe solar storms. Testing the system would use extremely high intensity very low frequency (VLF) radio waves to flush particles from radiation belts and dump them into the upper atmosphere. When I first heard of this on Monday morning, I thought it must be something from a fringe web site peddling dark conspiracy theories. But the newspaper reporting the news is real, and so is the team of scientists from New Zealand, the UK and Finland whose study of possible effects of the scheme is reported in a recent edition of Annales Geophysicae. You can find the article here: A web page from the University of Otago describing the research is here: I contacted the lead researcher on the team reporting the possible effects of the project, Dr. Craig Rodger of the Physics Department at the University of Otago in Dunedin, New Zealand. He proved very cooperative, accessible and helpful, and told me RBR is a serious project, ''money is starting to appear to investigate it in more detail'', and ''U.S. scientists with military connections are treating it seriously''. It is feared that testing the system could shut down worldwide HF communications for several days to a week, rendering the ionosphere a giant sponge for RF. I sent Dr. Rodger a comment from Ward Silver, N0AX, who speculated ''the sheer energy needed to accomplish it would tend to rule it out from the start, and I don't know where they would erect the necessary antennas.'' Dr. Rodger responded, ''This would be true, but they are hoping to rely on some of the non-linear processes in space plasmas, stealing the energy from the radiation belts to get the wave-amplitudes high enough. We know this is possible (in theory), as it happens naturally already. We don't know how easy it will be to get it happening under our control''. ''Also, as for erecting the antenna, there are two plans. One is to fly
VLF antenna in space. This could be a power problem. But for ground-based
systems, you probably already know that most major naval powers have big
VLF transmitters dotted over the globe. (Two of the US Navy transmitters
radiate one megawatt). While these are You can read Monday's article from the New Zealand Herald, here: 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 3 through 9 were 23, 0, 0, 0, 0, 12 and 25
with a mean of 8.6. 10.7 cm flux was 71.3, 69.6, 69.5, 69.5, 69.8, 71.4,
and 74.1, with a mean of 70.7. Estimated planetary A indices were 6, 3,
4, 4, 32, 12 and 9 with a mean of 10. Estimated mid-latitude A indices
were 5, 2, 2, 2, 19, 10 and 9, with a mean of 7.
Source: The American Radio Relay League
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