User's Manual

Chassis Systems Control
Leonberg
20 December 2021
Page 11 of 15
Model
Document
Dept.
FR5CUEC
User Manual ITA
XC-DA/ESR1
The radar cone describes the zone where the fascia has to be optimized. Any parts of the vehicle
inside the radar cone may influence the radar performance. Cables, brackets, bars etc. should
not touch the radar cone. The fascia in this zone may not have bends and edges as well as
changes in thickness or material or painting.
Based on the footprint on the top side of the radar PCB the cone is characterized by a vertical
and a horizontal opening angle. The footprint is centered regarding to the sensor housing. A
CAD model of the radar cone is available. The footprint for radar cone has the following
dimensions: (W x H) 95 mm x 84 mm
Radar cone definition for covered installation FR5CU:
The horizontal opening angle depends on the angle range that is evaluated by the sensor in
azimuth and elevation.
Radar cone:
• ±75° in horizontal direction (not including misalignment)
•±25° in vertical direction (not including misalignment)
6.2 Fascia design guidelines
Material
Material with low dielectric constant (ε
r
) and low dielectric loss factor tanδ at 77 GHz should be
used. Recommended are materials based on polypropylene (PP) and polymethyl methacrylate
(PMMA), while materials like polycarbonate (PC) and acrylonitrile butadiene styrene (ABS) are
still ok. The material shall be homogenous, compounds including glass fiber, carbon fiber or
metal particles are not recommended.
The fascia shall be designed for radar transparency. The thickness shall be a multiple of the
half wavelength (in the material) to minimize the influence of the fascia. The quality criteria of
radar transparency is the reflection coefficient of the radome/fascia. Tolerances of the overall
thickness and the dielectric constant of the used material influence the amount of reflection at
the radome/fascia. Additional influence occurs due to curvature of the fascia. Therefore the
radius has to be as large as possible. With sharp edges the negative influence will increase
significantly. Not allowed are ribs, structures and steps changing the thickness of the
radome/fascia.
Painting
The layer structure of the painting, typically made of three painting layers consisting of primer,
base coating and clear coating, will increase the effective permittivity value ε
r,eff
and dielectric
loss factor tanδ of the painted plate used as fascia.