Propagation... why do I miss some signals?

[cutty]

I found this ELF propagation link from sferics.com and plan on studying it a little. The goal is to find out whether a skip zone exists at ~16 kHz.
https://www.semanticscholar.org/paper/Mo...0ac651cd46

While you're absorbing the link you posted...
(here's direct link to paper:  WAVE GUIDE }

You might add these two additional factors... as 'starter' papers....
Impulse Earth Surface
Coupling Mechanism




There's a point where I become very enamored with the basic 'light switch' theory... throw the switch, stuff happens... hopefully.