Tom said:
>I've been considering the chance the ionosphere is that way
>for a long time and haven't found much evidence the signal
>only travels one way.
>
The only hard data I've ever seen that suggests the ionosphere itself
may contribute to "one-way propagation" is the extensive work of John
Wang at the FCC in the 1970s in validating North American signal
strength predictions in the AM broadcast band for frequency allocation
issues. The data indicates more transmission loss (absorption) on
East-to-West paths than on West-to-East paths for distances up to
2800km. The difference was about 13dB for frequencies greater than 830
KHz. That's a sizable difference, and would make a signal quite a bit
weaker in one direction compared to the other direction.
All of this was summarized by a gentleman at Boulder named Douglass
Crombie in IEEE Transactions on Broadcasting, Vol BC-25, No 3, September
1979, pages 86-89.
Carl K9LA
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