mmWave Design
Design Software Supports mmWave Automotive
Radar and Antenna System Development
By Dr. Milton Lien and David Vye, NI AWR Group
Ongoing developments in advanced
driver assist systems
(ADAS) are expanding the capabilities
and affordability of vehicles that
can alert and assist drivers using radar
technology mostly focused over the 76 to
81 GHz spectrum. These systems must
perform over a range of applications,
operating conditions, and object detection
challenges in order to provide reliable
coverage over the range (distance) and
field of view (angle) as dictated by the
particular driver assist function. This
article examines some of the challenges
behind developing millimeterwave
(mmWave) radar systems and the
antenna array technologies that will be
responsible for the next generation of
smart cars and trucks.
OVERVIEW OF ADAS
To obtain high safety ratings, automobile
manufacturers are equipping their new
models with driver assistance systems
made possible through a network of
sensors that perform specific safety
functions. Manufacturers are currently
implementing these systems based
on vision sensor technology and radar
systems operating at either 24 and/
or 77 GHz. Vision systems detect lane
markings and process other visual road
information, however, they are susceptible
to inadequate performance due to
precipitation, particularly snow and fog,
as well as distance.
On other the hand, long-range radar
(LRR) supports multiple functions, comfortably
handling distances between 30
and 200 meters, and short-range radar
(SRR) can detect objects below 30 meter
distances. While the 24 GHz frequency
band, which addresses SRR detection,
is expected to be phased out of new
vehicles by 2022, today it is commonly
found in hybrid architectures. Meanwhile,
the 77 GHz band (from 76-81
GHz) supporting LRR is expected to provide
both short and long-range detection
for all future automotive radars. Figure
1 provides details on short/medium and
long-range radar.
Technical advantages of the 77 GHz
band include smaller antennas (a third
Figure 1: Different ranges, fields-of-view (FOV,) and functions for advanced driver
assist systems. (Image courtesy of Analog Devices).
Table 1: Different radar architectures and their technical advantages/
disadvantages in target detection, range, robustness and resolution.
of the size of the current 24 GHz ones),
higher permitted transmit power, and,
most importantly, wider available
bandwidth, which enables higher object
resolution. As a result, advances in
radar modulation techniques, antenna
beam steering, system architecture, and
semiconductor technology are driving
14 MW November - December 2017 www.mwee.com
