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 (m
ρ
) where:
1000 m
ρ
= 1 rho = 100 % reflection
Impedance mismatches can also be expressed logarithmically in terms of Return Loss where:
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
