Ongoing developments in advanced driver assistance 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. Part 1 provided an overview of ADAS systems and discussed various radar systems and architectures. Part 2 discusses multi-beam and multi-range design and examines antenna design for multiple-input, multiple-output (MIMO), and beam-steering technologies for 5G that will be useful for automotive safety in the future.
Multi-Beam/Multi-Range Design
A typical adaptive-cruise-control (ACC) stop-and-go system requires multiple short- and long-range radar sensors to detect nearby vehicles. The shorter-range radar typically covers up to 60 m with an angle coverage up to ±45°, allowing the detection of the vehicle’s adjacent lanes that may cut into the current travel lane. The longer-range radar provides coverage up to 250 m and an angle of ±5° to ±10° to detect vehicles in the same lane, further ahead.
To support multiple ranges and scan angles, module manufacturers such as Bosch, DENSO, and Delphi have developed and integrated multi-range, multi-detection functionality into increasingly capable and cost-sensitive sensors using multi-channel transmitter (TX)/receiver (RX) architectures. These different ranges can be addressed with multi-beam/multi-range radar by employing radar technology such as frequency-modulated-continuous-wave (FMCW) and digital beamforming with antenna-array design.