Rohde & Schwarz 1336.5401.02, User Manual, Page: 62 / 123

Operating the R&S QAR
R&S
®
QAR
62 User Manual 1178.7200.02 ─ 09
5.3 Bumper Measurements
In real cases, the vehicle built-in radar sends a signal that crosses the bumper, is
reflected and crosses the bumper again. Similarly, the R&S
QAR antennas send sig-
nals that cross the bumper, are reflected from the reference reflector pins and cross
the bumper back. The received signals are measured and compared to the free-space
measurement (normalization) to obtain the transmission loss (or two-way attenuation)
caused by the bumper in multiple points.
The R&S QAR uses 64 discrete frequency points to cover the frequency range 76 GHz
- 81 GHz. Thanks to the multistatic imaging of the reflector pins, the analyzed bumper
is irradiated from different angles (from -38° to +24°), as shown in figure Figure 5-16 .
Figure 5-16: Irradiation area: 3D, top view and lateral view
The mean two-way attenuation is calculated as follows:
-20
·
log
10
(mean attenuation coefficient).
The mean attenuation coefficient is calculated as an average between the values
obtained for all discrete frequency points and for all the reflector pins used.
The typical procedure when measuring the transmission loss (attenuation) caused by a
bumper is as follows:
1. Start the R&S QAR.
The software starts automatically. For more information, see Chapter 5.3.2,
"Graphical User Interface" , on page 63.
Bumper Measurements