Step 1. Add the isotropic gain (in dBi) of
your antenna twice to thepathloss (in dB).
Step 2. Add your transmitted power in
dBW = 10 log P (whereP is transmitted
power in watts)
The result is your echo power (in dBW) that is
available at your antenna terminals.
Example. At f = 432 MHz, you havean antenna
gain of 26 dBi and can supply 1500 watts (32 dBW)
to the antenna terminals. Then your returning echo
has power
26 + 26 + 32 - 261.5 = -177.5 dBW
or
10^{-17.75} = 1.78 x E(-18) watts