Radar has the unique ability to instantaneously detect objects and measure their velocity via the Doppler shift of radar signatures and performs even in bad weather conditions such as rain, fog and snow. It enables applications like adaptive cruise control, lane change assist, autonomous emergency braking, and stop-and-go traffic jam systems to name a few.
These benefits are driving automakers to adopt radar in increasing numbers. Recently the National Highway Traffic Safety Administration (NHTSA) in the US reached an agreement with 20 automakers, to equip all production vehicles with low-speed Automatic Emergency Braking (AEB), including forward collision warning systems by 2022, a safety feature often enabled by radar.
As vehicles evolve from Advanced Driver Assistance Systems (ADAS) to full autonomous driving, sensors such as radar and cameras are the critical input devices that enable the vehicle to accurately sense the environment around it. Future vehicles may include several types of radar sensors for short, mid and long range to provide a full 360° surround view of the car. When combined with other sensors in the vehicle, this information provides the context needed for the vehicle to make decisions.
Traditionally many of the radar sensors use frequencies in the 24 Hz band, but due to spectrum regulations the use of some of these frequencies will be phased out by 2022 in Europe and the US. Regulating authorities have instead opened up the 77 GHz band, and most research and new automotive radar applications therefore focus around the 76-77 and 77-81 GHz band. The benefit of having a higher frequency with higher bandwidth radar sensors is that it improves range resolution by almost 20 times, and velocity resolution by 3 times, whilst reducing sensor size compared to the 24 GHz sensors.