![](https://csdnimg.cn/release/download_crawler_static/11434318/bg6.jpg)
6
Steffen Heuel, Tobias Köppel and Sherif Ahmed
Rohde & Schwarz, Munich, Germany
A
dvanced driver assistance systems (ADAS) in
cars assist the driver and increase road safety,
and these systems are widely deployed in
many modern vehicles and car types. Cur-
rently, autonomous driving is a major focus of the au-
tomotive industry, and R&D institutes are making head-
lines with fully automated cars driving hands-off along
the highway—even in cities with dense trafc. It is cer-
tain that autonomous driving will become reality in the
near future.
Camera, LiDAR and radar sensors are key enabling
technologies in this area. Millions of automotive radars
are produced every year, and car manufacturers are start-
ing to deploy them as standard equipment in all higher-
class cars. Today, automotive radar sensors are mainly
used to increase driving comfort and prevent crashes.
Most automotive radar sensors that enable adaptive
cruise control (ACC) operate in the conventional 76 to
Evaluating 77 to 79 GHz
Automotive Radar Radome
Emblems
77 GHz frequency range to sense other cars and objects
far ahead. Advanced radar capabilities, however, de-
mand larger bandwidths, with coverage up to 81 GHz to
enable 360 degree radar vision around the vehicle. This
is required for ADAS functions such as lane change as-
sistance and blind spot detection, where high resolution
and a wide operating angle are essential. Additionally,
extending the automotive frequency band to 81 GHz
helps mitigate interference. Altogether, this puts pres-
sure on radar system integration to be functional across
a wider frequency band than in the past.
Automotive radars must be masked by a cover,
known as a radome, which is constructed from a trans-
parent RF material. Radomes can be an emblem or a
car bumper, with the radar behind it as illustrated in
Figure 1. Although an emblem may be underestimated
and dismissed as a simple plastic cover, it is actually a
sophisticated RF element that often degrades radar de-
tection range and accuracy. Emblems need to satisfy the
requirements of aesthetic appearance, often including
the 3D shape of the car logo. However, this is usually
in conict with the RF performance needed for 76 to
81 GHz operation. On the other hand, car bumpers are
typically coated with metallic paint, which is, of course,
critical for the automotive radar frequencies. So it be-
comes essential to validate the material characteristics
and examine their inuence on the radar sensors. Con-
sidering the criticality of the applications where radar
sensors are deployed, uncertainties are unacceptable.
Consequently, engineers and manufacturers need new
measurement capabilities to evaluate the effect of em-
s Fig.1 Radar mounted behind the front emblem, which is a
radome.
www.mwjournal.com/articles/29574