Topband: More anecdotal "stories" to cause one to stop and....
rfry at adams.net
Fri Sep 13 07:43:47 EDT 2013
Jack WS3N wrote:
>Then it would seem that what you call the surface wave must be the
>remaining part of the complete solution, and so it must decay exponentially
>in the vertical direction. ... a decaying solution can't be projected in a
>straight line and assumed to reach the ionosphere.
The radiated field of a vertical monopole present on the surface of lossy
earth decays at greater than a 1/R rate. But, for example, the field shown
at a horizontal distance of 0.1 km in my surface wave plot for an elevation
angle of 5 degrees is not located on the surface of the earth. It is about
9 meters above it, and in fact, is a space wave.
Space waves DO decay at a 1/R (non-exponential) rate until they reach the
Here is a link to a clip from Radio Engineers' Handbook by F.E. Terman (1st
Edition), showing that the greatest single-hop range for radiation from a
1/4-wave monopole leaves the monopole at elevation angles below 5 degrees.
The reduction in skywave field intensity seen in this clip beyond 150 miles
downrange is due to the 1/R losses of those longer paths.
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