Multi hopping radio waves
"Reg Edwards" wrote in message
...
With multi-hops through the ionosphere there will be reflections from
the ground between adjacent hops. If there are N hops there will be
N-1 ground reflections.
At each reflection a signal loss is incurred. But the ground is a
variable quantity.
What rule of thumb relating to reflection loss is used by radio
professionals when calculating path loss?
At the back of my mind I have a figure of 5 dB per reflection. Is this
in the right ball park?
Thank you.
----
Reg.
Reflection loss can vary from zero to infinity; depending on the material
and angle of incidence.
For example; take the oblique incidence of a horizontally polarized EM wave
on an air/rocky
ground interface of:: conductivity 2 mS/m, and relative permittivity 15.
The reflection loss
at zero degrees is 4.4 dB, increasing to 21.4 dB at the pseudo Brewster
angle of 76 degrees, and
0 dB at 90 degrees. Ref. Advanced Engineering Electromagnetics, C. A.
Balanis, pp 206 - 214.
I have copies of the Mathcad calculations if anybody is interested.
Frank
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