User's Manual

Product Description, User Manual, Installation Guideline Doc. No. xxxxxxxxx
SENSOR MODULE, RADAR, SRR, NB Page 12 of 16
6.4.2 Effect Of Type- And Thickness Of Fascia Material
Autoliv has examined various fascia material samples with a thickness of 2.5 – 4 mm. For those
samples, the radar signal is attenuated by 0.5 – 2 dB (corresponds to reduction of the range of
coverage of 2 – 11%). Impact reducing material (foam) causes additional attenuation, especially when
water is absorbed. Therefore, there shall be no impact reducing material in the antenna areas as
described in 6.2 – 6.3. There shall also be no metallic parts, snap-on contacts, clips or double wall
laminations in the antenna areas as described in 6.2 – 6.3.
Fascia loss effects can be minimized by proper control of the material thickness and dielectric constant.
Autoliv recommends the analysis of sample materials to determine the dielectric constant and proper
thickness for optimal performance. Thickness and dielectric constant must be controlled to a tolerance
of ±10% max to ensure optimal performance. Please consult Autoliv with prospective fascia
configurations to assess potential performance impacts.
6.4.3
Effect of the paint
Depending upon the type of paint, number of coatings, base coats used, etc., the attenuation of the
radar signal due to the paint varies roughly between 2 and 5 dB (corresponds to reduction of coverage
between 11 and 25%). Because attenuation has significant impact on performance, prior inspection of
the material and paint samples are suggested.
Autoliv recommends the characterization of painted fascia samples to determine the radar signal loss
effects. Autoliv sensor specifications assume a maximum signal loss (2-way) of 4 dB due to fascia
effects. Materials and paints that exhibit greater than 4 dB loss will degrade the specified performance.
As noted in 6.4.2 performance can be optimized by proper control of the fascia material thickness and
dielectric constant.
New fascia, paint material or process by the OEM should be submitted to Autoliv for characterization.
6.4.4
Smoothness of Fascia in Front of Antenna
Avoid sharp vertical or horizontal character lines in front of sensor antenna. Horizontal character lines
have less of an effect on sensor performance.
Figure 12 : Character lines