NEW: Is HF radio signal propagation reciprocal?

[NW7US]

One would think that ionospheric radio propagation would be reciprocal. That is, the signal strength in one direction should be the same as in the reverse, or reciprocal, direction. In HF ray-trace theory, the distance is the same and the ionospheric control points-the points where the wave is reflected (or more properly, refracted) back to the ground-should be the same. But I decided to run some test circuits using the ACE-HF System Simulation & Visualization software to see if signal predictions were the same in both directions. (See my review of the new ACE-HF V2.05 model in the May 2006 issue.)

See the full story at:

http://hfradio.org/ace-hf/ace-hf-reciprocal.html