(2018-11-09, 18:28)dupreezd Wrote:(2018-11-09, 18:13)mwaters Wrote: Right or wrong, https://en.m.wikipedia.org/wiki/Skip_zone seems to imply that there is no skip zone at ELF.
We are not receiving detecting RF like in a radio wave.
It finally dawned on me why you believe that, Dries. Audio sound waves from a speaker that are detected by our ears actually overlaps a limited range of radio frequencies. (That was difficult for me (and countless others) to comprehend. After all, ~15 kHz can be heard! It "can't" be RF radio waves!)
Lightning strikes definitely propagate an RF signal that are detected by our BT radio receivers. We are indeed receiving RF radio waves, even though we cannot possibly detect the sound from distant thunderstorms. Think about it: our BT receivers use antennas and probes, not microphones.
There are VLF and LF radio stations whose frequencies are in our VLF or LF band. And some of them continue to be a source of interference to a few stations on our network.
Interestingly, there is a ham band around 137 kHz (2200 meters).
I was wrong when I wrote ELF. The ELF band is either 3 Hz to 30 Hz or 3 Hz to 30 kHz.
