Measurements and result displays
R&S
®
QAR50
39
User Manual 1179.4992.02 ─ 02
Figure 8-1: Principle of the reflection measurement
1
= Cluster 1
2
= DUT
3
= Cluster 2
straight line = Stimulus signal
dashed line = Reflected energy
The reflected energy does not pass through the DUT and contributes to performance
degradation as a result. Reflected signals reduce the performance of the radar and can
even interfere with the received signals, leading to effects as described in application
note
. Areas with a high reflection can have various causes, for example mate-
rial defects, undesired interaction between several layers of materials, excessive
amount of certain materials, or foreign objects.
The R&S
QAR50 achieves spatially resolved reflection measurements of a DUT by
linking the information collected by the distributed transmit and receive antennas in a
coherent operation. The resulting millimeter wave image, diagram and numerical
results allow for an intuitive evaluation of the DUTs reflection behavior.
For more information about the result display available for the reflection measurement,
see
Chapter 8.3, "Result displays"
8.2.2
Transmission measurement
The stimulus signal is split in a reflected and a transmitted part. Therefore, it is of inter-
est to measure not only the reflection characteristics of a DUT, but also the transmis-
sion properties. The result (transmission attenuation) is the ratio of the energy mea-
sured at the receiving cluster to the stimulus signal sent by the transmitting cluster.
For the transmission measurement, both clusters send a signal that passes through
the DUT. The passage through the DUT attenuates the signal. The attenuated signal is
measured by the opposite cluster. The resulting transmission attenuation is the aver-
age of those two measurements.
Measurement
