What is Millimeter Wave (MMW) Automotive Radar PCB?

Electrification, connection, intelligence, and sharing are the major developing trends of future automotive technology. Green auto is the inevitable trend. Meanwhile, DAS, ADAS, self-driving, driverless are in gradual development. Therefore, the auto anti-collision radar is the most important part of the developing trends.


1. Brief Introduction of Automation

1.1 MMW Radar is the mainstream of auto anti-collision radar category

Compared with other radars or sensors such as Lidar, Ultrasonic radar, IR sensor, and camera, MMW radar has advantages in auto-collision avoidance technology. In other words, MMW radar with Frequency Modulated Continuous Waves (FMCW) is the developing mainstream of auto anti-collision radar.

Take Audi A4 as an example. In Audi A4, it is equipped with one monocular camera located at the upper center of the front window, five MMW radars (77 GHz LRR—front bumper, 24 GHz SRR–two sides of the front bumper, 24 GHz SRR at the back), and eight ultrasonic radars in the front and back).


1.2 What is Millimeter Wave (MMW)?

Millimeter Wave (MMW) refers to extremely high frequency (EHF), which is very suitable for 5G networks. In Millimeter Wave systems, the transmission frequencies are between 30 GHz and 300 GHz whose wavelengths are between 1 millimeter and 10 millimeters. Millimeter Wave (MMW) technology is widely used in radar systems and satellites.


1.3 Auto MMW radar PCB

There are three typical types of auto anti-collision radar:

  • 24 GHz SRR (Short range radar)
  • 77 GHz LRR (Long range radar)
  • 79 GHz MRR (Mid range radar)

The PCB applications include antenna PCB, radio frequency (RF) PCB and control PCB. Among them, the antenna design is the most important. In 24 GHz SRR, antenna and RF are generally designed separately, but sometimes they are also designed in the same layer. Conversely, for 77 GHz LRR and 79 GHz MRR, antenna and RF are generally designed in the same layer, while they can be designed in separate external layers as well.

The MMW radar module

Figure 1: The MMW radar module



1.4 The development of MMW radar

Millimeter wave (MMW) radar board has three fascinating developing trends:

  • MMW radar serves as automotive sensors, mainly apply to L2, L3 level of automatic driving
  • MMV radar and IoV (Internet of Vehicles) together realize L4 and L5 advanced car driving

24 GHz SRR, 77 GHz LRR and 79 GHz MRR cooperate with the in-car network (TBOX, vehicle Ethernet), V2X, and long-distance communication of ICV (Intelligent Connected Vehicle).


The development of automation

Figure 2: The development of automation



2.Capability and Roadmap

2.1 Auto radar development milestones of our company


Auto radar development milestones of our company

Figure 3: Auto radar development milestones of our company


2.2 MMV radar product applications of our PCB

  • Automotive (24 GHz SRR, 77 GHz LRR and 79 GHz MRR)
  • UAVs (Collision avoidance & Altimeter)
  • Intelligent traffic (Speed & Flow measuring)
  • Intelligent security (Perimeter & Regional)
  • 5G MMW (MIMO antenna & Base station)
  • Intelligent hardware (Lighting & ship blind compensation)
  • Industrial applications (Liquidometer & Industrial robot radar)
  • Ultra high speed/short distance telecommunication
  • Long-distance satellite communication
  • MMW medical care
  • Etc.


2.3 The product applications of 24G, 77G and 79G auto anti-collision radars

  • BSD (Blind Spot Detection)
  • LCA (Lane Change Assist)
  • EAF (Exit Assistance Function)
  • ACC (Adaptive Cruise Control)
  • CWAB (Collision Warning with Auto Brake)
  • FCW (Front Collision Warning)
  • AEB (Autonomous Emergency Braking)
  • Etc.


2.4 Key capability indicator of radar PCB

2.4.1 Antenna design

The mainstream designs (mass production) of the antenna at our company are:

  • Patch
  • Comb-like
  • Diffused patch antenna


Various kinds of antenna design

Figure 4: Various kinds of antenna design


2.4.2 Feeding design

Four types of mainstream feed design products have been produced:

  • Coplanar microstrip feed
  • Coaxial through-hole feed
  • Slot-coupled feed
  • Electromagnetic coupling feed


2.4.3 Transmission line design

Three types of typical transmission line design products have been produced:

  • Microstrip (MS)
  • Grounded coplanar waveguide (GCPW)
  • Substrate integrated waveguide (SIW)