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2.1.3 Free space losses
Spreading is the principal contributor to signal loss for line of sight propagation.
As a signal radiates it spreads or expands into a spherical surface. The available
RF power is distributed over this surface and weakens with increasing range.
The signal is reduced by 6 dB for every doubling of distance from the source.
The loss path between the source radiators with spherical patterns is computed
using the following equation:
Lp(dB)= 92.45 + 20*log
10
(F)+20*log
10
(d)
Lp = Path loss
F= frequency in GHz
dB = decibels
d= Distance in kilometers
Example:
A distance of 6 kilometers provides a free space loss of 115.67 dB at 2.4 GHz.
