Take a Look at the PCB Design of Audi A8 Millimeter Wave Radar

Many high-performance automotive auxiliary systems rely on radar to collect information around the vehicle. Their utility is to accurately calculate the distance and relative speed between the vehicle and the vehicle in front according to the reflected wave principle. Bosch's fourth generation long-range radar sensor (long-range radar, lrr4) is designed based on the R & D and production experience of the third generation radar. Lrr4 is the same as the previous generation products, uses the 77 GHz band and has no movable parts. All components are fixedly installed in all parts of the vehicle to improve the stability of the system. The lrr4 radar sensor integrates two electronic boards, including the microcontrollers of NXP and STMicroelectronics, and the power management IC of Bosch. The radio frequency (RF) board adopts an asymmetric structure based on a hybrid PTFE / FR4 substrate and is equipped with a planar antenna. Infineon 77 GHz silicon germanium (SiGe) monolithic microwave integrated circuit (MMIC) is used as high frequency transmitter and receiver.

Lrr4 comes from Bosch and is a multi-mode radar with six fixed radar antennas. Four centrally arranged antennas can provide high-speed recording of the environment, create a focused beam with an aperture angle of 6 , and minimize traffic interference in adjacent lanes. In the case of near-field, the two external antennas of lrr4 can expand the field of view angle to 20 , with a range of 5m, and can quickly detect whether the vehicle enters or leaves the lane (Fig. 1).Figure 1: remote radar sensorAPTIV's short-range radar sensor consists of two transmitters and four receiver channels. It works in the 76-77 GHz band, which is the standard configuration for automotive radar applications. PCB uses a monolithic microwave integrated circuit and several cavity waveguides. The RF PCB substrate is made of glass reinforced hydrocarbon based ceramic laminate and completely free of PTFE (Fig. 2 and Fig. 3).

Figure 2: overview of APTIV r3tr 76ghz short range radarFigure 3: APTIV r3tr 76ghz short range radar electronic PCBMain features of lrr4:

In independent mode, the height is measured by elevation beam, which can distinguish fixed obstacles, so as to make safe braking response to stationary objectsIt can be used at high speedThe self calibration function (horizontal) reduces the associated installation costs

Compact size for easy installation in the vehicleThe scalable system has multiple sensor configurations, including data collected by fusion sensors (optional)Through the optional lens or radome heating function, the sensor performance is not affected by weather conditions

Concealed behind bumper / RadomeThere are no movable parts, so it has high seismic stabilityHigh speed can and FlexRay interfaces for easy integration in the vehicle