There is an interesting article today on Spaceweather about the Van Allen radiation belts and how they are kept clear of the earth's surface by the powerful VLF transmitters used to talk to submarines. Here's a link to the article....check it out: http://spaceweather.com/ 73, J.B., VE3EAR LowFER Beacon "EAR" 188.830 kHz. QRSS30 EN93dr