Radiodetection T631 TDR - Page 33

Reflection coefficient
ρ=
Ar
At
where
Ar = amplitude of reflected pulse
At = amplitude of transmitted pulse
The amplitude of the reflected pulse cannot normally exceed that of the transmitted pulse and
therefore the reflection co-efficient cannot exceed unity. It is usual therefore to express the
reflection in percentage terms or millirhos (mρ) where:
1000 mρ = 1 rho = 100 % reflection
Impedancemismatches can also be expressedlogarithmically in terms of ReturnLosswhere:
Return Loss = 20 log
10
At
Ar
dB
or Return Loss = 20 log
10
1
ρ
dB
T631 OPERATING MANUAL 33
Radiodetection Ltd. 00901209-6
At
Ar