BIRD 4044 Series, Operation Manual

Page: 13 / 16

Maintenance
6
Mismatch Uncertainty
Mismatch uncertainty is a factor that can affect measurement accuracy. When a
source and an antenna have different impedances, some signal will be reflected
back to the source. The non-directional power sensor does not differentiate
between forward and reflected power, so any mismatch will impact the
measurement. The larger the reflected energy level the greater the uncertainty
of the measurement, due to high VSWR and poor Return Loss. See
Figure 3
for
calculations affecting accuracy.
Figure 3 Mismatch Uncertainty