Operating the R&S
QAR
R&S
®
QAR
44
User Manual 1178.7200.02 ─ 04
The first value "a
77
" is the one-way mean attenuation in the frequency range from
76
GHz to 77
GHz.
The second value "a
81
" is the one-way mean attenuation in the frequency range
from 76
GHz to 81
GHz.
The limits for the transmission verification measurement are plate-specific.
5.2
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 5-6: 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.
Bumper Measurements
