Very interesting Phil thanks, but I believe there were far more VLF and MF transmissions back in the time period from 1900 to 1940 than there are today.
For a long time it was believed that longer wavelengths (lower frequencies) were essential for long-range communications. That is why shipboard communications and point-to-point communications were focused on the frequencies below 450 kHz - the lower the better. The AM "standard broadcast band" was established in about 550 to 1600 kHz believing that those frequencies were only useful for short ranges up to a few tens of miles, which is what the commercial broadcast station allocations were designed to serve. Of course us Hams were given use of the shorter wavelengths (200 meters or less in wavelengths - or about 1600 kHz or above in frequency) because it was "obvious" someone would be lucky to communicate across a small town with them, if that far. And then that all changed when a few Hams broke away from QRMing each other on 200 meters and started exploring the shorter wavelengths. Now there is comparatively little going on down there. As the article mentions, submarine comms are at VLF. Low powered aircraft beacons, some GPS correction beacons (also low powered) and some Ham activity under the special licenses. I haven't listened down there in a while but that's all that comes to mind. So the source of the "bubble" mentioned in the article seems a mystery -- or is it something that has been there since Marconi launched the radio business and is now just being noticed? 73, Ron AC7AC -----Original Message----- From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Phil Hystad Sent: Thursday, May 18, 2017 5:23 PM To: elecraft Subject: [Elecraft] OT -- Ham radio operators contribute to protecting the Earth I thought some other ham operators might like to read how they are helping to build a protective bubble around the Earth. https://www.theatlantic.com/science/archive/2017/05/wow-guys/527193/ 73, phil, K7PEH ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to r...@elecraft.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
