Stanford University's VLF Research Group
http://vlf.stanford.edu/research The Stanford University VLF Group investigates the Earth's electrical environment, its upper atmosphere, lightning discharges, radiation belts, and the ionized regions of upper atmosphere known as the ionosphere and magnetosphere. Much of our work involves the use of very low frequency (VLF) electromagnetic waves which are generated by lightning discharges, by man-made transmitters and by energetic radiation belt electrons. We investigate the generation of these waves and the manner in which they propagate in and scatter from various regions of the upper atmosphere. We use VLF waves as diagnostic tools to investigate physical processes in the Earth's plasma environment. Under the direction of Professor Umran Inan , the VLF group carries out extensive observational programs at multiple sites around the world and on satellites. In addition, extensive theoretical modeling and interpretation work is carried out, on quantitative modeling of high-altitude optical emissions known as sprites, blue jets, and elves, on modeling the propagation and scattering of electromagnetic waves in the Earth-ionosphere waveguide, and on other related electromagnetic wave and plasma physics problems. VLF Data http://vlf.stanford.edu/vlfdata/ === w9gb ----- Original Message ----- From: "G. Beat" <[email protected]> To: [email protected] Sent: Sunday, December 12, 2010 7:23:44 PM Subject: Re: [amsat-bb] LF Satellite ideas? ==== Specific to your VLF capabilities on this satellite ...... Look at the 1997 PhD disseration by Steve Cummer submitted to the Department of Electrical Engineering at Stanford University: Lightning and Ionospheric Remote Sensing Using VLF/ELF Radio Atmospherics http://www-star.stanford.edu/~vlf/publications/theses/cummerthesis.pdf at Stanford University: Lightning and Ionospheric Remote Sensing Using VLF/ELF Radio Atmospherics http://www-star.stanford.edu/~vlf/publications/theses/cummerthesis.pdf This research was supported by the Office of Naval Research through grants N00014-93-1-1201 and N00014-95-1-1095, by the Air Force Office of Scientific Research through grant F49620-97-1-0468, and by the Air Force Phillips Laboratory through grant F19628-96-C-0149. ==== That should get you started Bob. Greg w9gb ------------------------------ Message: 16 Date: Sat, 11 Dec 2010 14:13:33 -0500 (EST) From: "Bob Bruninga " <[email protected]> Subject: [amsat-bb] LF Satellite ideas? To: [email protected] Message-ID: <[email protected]> Content-Type: text/plain; charset=us-ascii Is 137 KHz possible from space? Our next Cubesat will have a 1100 meter long antenna (think tether satellite). It will ultimatelly be an electrodynamic tether but the first one will have NO ACTIVE ELECTRONICS connected to the tether. So I have asked them to make it 1100m long instead of a generic 1km tether to try to make it resonant in an amateur band. THe path loss at 137 KHz is 60 dB LESS than it is at 2 meters, so it shouldn't take much to communicate with an 1100m long antenna. I'm sorry I didnt think of this sooner, but I need a real SCIENCE justification for this. Maybe LF that low will never punch through the ionosphere, or maybe it will be completely absorbed. Can give good science on this idea? Bob, WB4APR ------------------------------ Message: 16 Date: Sat, 11 Dec 2010 14:13:33 -0500 (EST) From: "Bob Bruninga " <[email protected]> Subject: [amsat-bb] LF Satellite ideas? To: [email protected] Message-ID: <[email protected]> Content-Type: text/plain; charset=us-ascii Is 137 KHz possible from space? Our next Cubesat will have a 1100 meter long antenna (think tether satellite). It will ultimatelly be an electrodynamic tether but the first one will have NO ACTIVE ELECTRONICS connected to the tether. So I have asked them to make it 1100m long instead of a generic 1km tether to try to make it resonant in an amateur band. THe path loss at 137 KHz is 60 dB LESS than it is at 2 meters, so it shouldn't take much to communicate with an 1100m long antenna. I'm sorry I didnt think of this sooner, but I need a real SCIENCE justification for this. Maybe LF that low will never punch through the ionosphere, or maybe it will be completely absorbed. Can give good science on this idea? Bob, WB4APR _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
