[Elecraft] Thinking out loud again...

[k6se@juno.com]

Ron, AC7AC wrote:

"Spunik was on HF, among others. Sputnik, especially, put a wonderfully
loud signal onto the surface even with its tiny little transmitter."
==========
Lest we forget, Sputnik was above the E-layer, but below the F-layer. 
The ISS is well above both of those ionospheric layers and will have to
penetrate both to reach the ground.

Of course, a signal arriving at high angles to the ionosphere should have
no trouble penetrating it in either direction except perhaps on the
lower-frequency amateur bands where the critical frequency is not low
enough for penetration on those bands.

"Critical frequency" is defined as the lowest frequency at which a signal
beamed straight up will still be refracted straight down by the
ionosphere.  Signals beamed straight up which are at a
higher-than-crticial-frequency will penetrate the ionosphere.

The critical frequency varies with time of day and solar activity, of
course.

73, de Earl, K6SE