As millimeter-wave technology continues to expand into automotive electronics, smart homes, industrial systems, and intelligent infrastructure, millimeter wave radar PCB technology is attracting increasing attention.
Millimeter-wave radar can detect the position, distance, velocity, and movement of objects by transmitting and receiving electromagnetic waves at high frequencies. Compared with cameras and some conventional sensors, radar can operate under challenging lighting and weather conditions while providing useful sensing information without requiring detailed visual images.
This makes automotive radar PCB technology particularly important for advanced driver assistance systems (ADAS) and future intelligent vehicles.
This article examines millimeter-wave radar PCB technology from two perspectives:
- The frequency bands, characteristics, and development trends of automotive millimeter-wave radar.
- Major application scenarios for millimeter-wave radar products.
Automotive Millimeter Wave Radar Frequency Bands
From a frequency-band perspective, two major frequency ranges have historically been associated with automotive radar applications: 24GHz radar and 77GHz radar.
Although both technologies can be used for vehicle sensing, their operating characteristics and typical applications are different.
24GHz Radar: Applications and Characteristics
24GHz radar has been widely used for applications such as blind-spot detection (BSD) and lane-change assistance (LCA).
Radar sensors for these applications are commonly positioned around the rear or side areas of a vehicle. They monitor surrounding traffic and help determine whether another vehicle is approaching from a blind spot or whether the adjacent lane is occupied.
A major advantage of 24GHz technology is its relatively mature ecosystem and established application base.
However, compared with higher-frequency automotive radar, 24GHz systems generally have limitations in terms of available bandwidth, antenna size, resolution, and sensing performance.
For this reason, 24GHz radar is increasingly focused on applications where its performance and cost advantages remain appropriate.
77GHz Radar: Higher Frequency and Higher Resolution
77GHz radar operates at a significantly higher frequency and provides broader bandwidth and shorter wavelengths than 24GHz systems.
These characteristics allow automotive radar sensors operating around 77GHz to achieve improved range and velocity measurement as well as better target separation and angular resolution when the overall radar architecture is properly designed.
77GHz radar is therefore widely associated with forward-looking automotive applications.
Typical applications include:
- Automatic Emergency Braking (AEB)
- Adaptive Cruise Control (ACC)
- Forward Collision Warning (FCW)
- Forward vehicle detection
- Traffic monitoring
- Object and obstacle detection
For these applications, the radar must accurately determine the distance and relative velocity of vehicles, pedestrians, and other objects.
The PCB used in such radar systems must therefore support high-frequency signal transmission with carefully controlled electrical characteristics.
SiGe and CMOS Technologies for Millimeter Wave Radar
At the semiconductor level, two important technologies used in millimeter-wave radar systems are Silicon Germanium (SiGe) and Complementary Metal-Oxide-Semiconductor (CMOS).
SiGe Technology
SiGe technology has been widely adopted in high-frequency and RF applications because of its mature high-frequency transistor technology and strong performance at millimeter-wave frequencies.
It has supported the development and mass production of automotive radar chipsets operating in the 77GHz range.
Another important advantage is its ability to provide strong RF performance under demanding operating conditions.
CMOS Technology
CMOS offers significant advantages in terms of integration and manufacturing scalability.
As semiconductor technology continues to develop, RF, baseband, processing, and other functions can increasingly be integrated into highly compact system-on-chip (SoC) architectures.
This can reduce system size, simplify design, and potentially reduce overall cost.
SiGe and CMOS therefore have different technical strengths, and both technologies may continue to coexist in automotive radar applications for some time.
Why PCB Technology Is Critical for Millimeter Wave Radar
As operating frequencies increase, PCB design becomes increasingly important.
At millimeter-wave frequencies, even small variations in PCB geometry or material properties can influence signal performance.
Important factors include:
- Dielectric constant (Dk)
- Dissipation factor (Df)
- Trace width
- Trace spacing
- Copper surface roughness
- Transmission-line geometry
- Layer stack-up
- Impedance control
- Via structure
- Manufacturing tolerances
For this reason, a radar PCB is more than a conventional circuit board.
The PCB becomes an important part of the RF signal path, and its material and manufacturing quality can directly influence insertion loss, signal integrity, impedance consistency, and overall radar performance.
Advantages of Millimeter Wave Radar Sensors
Among modern automotive sensors, radar offers several important advantages.
Different sensors have different strengths, so future intelligent vehicles are likely to rely on sensor-fusion architectures rather than a single sensing technology.
A typical system may combine:
- Radar
- Cameras
- Ultrasonic sensors
- LiDAR
- GNSS
- Inertial sensors
Each technology contributes different information.
Radar is particularly valuable because it can provide distance and velocity information and can continue operating in many challenging environmental conditions.
All-Weather Sensing Capability
One of the major advantages of millimeter-wave radar is its ability to operate in a wide range of environmental conditions.
Depending on system design, radar can continue providing useful sensing information under conditions such as:
- Darkness
- Bright sunlight
- Fog
- Light rain
- Dust
- Snow
This does not mean radar is completely unaffected by severe weather. Environmental conditions can still influence sensing performance.
Nevertheless, its environmental robustness makes radar an important component of ADAS sensor-fusion systems.
24GHz vs. 77GHz Automotive Radar
The choice between 24GHz and 77GHz depends on the intended application, sensing range, resolution requirements, cost, and system architecture.
| Feature | 24GHz Radar | 77GHz Radar |
|---|---|---|
| Frequency | Around 24GHz | Around 77GHz |
| Wavelength | Longer | Shorter |
| Typical applications | BSD, LCA | AEB, ACC, FCW, forward sensing |
| Bandwidth | Relatively limited | Generally wider |
| Resolution potential | Lower | Higher |
| Antenna size | Relatively larger | More compact |
| Long-range sensing | More limited | Better suited |
| Automotive adoption | Mature applications | Increasingly important |
The higher operating frequency of 77GHz systems allows more compact antenna structures and higher potential resolution.
However, this also places greater demands on PCB material selection, manufacturing precision, RF design, and process control.
Automotive Radar Development Trends
The automotive radar market continues to evolve as vehicles move toward higher levels of automation.
One important question is whether 77GHz technology will completely replace 24GHz systems.
In practice, the development path is more complicated.
Different radar sensors serve different functions, and manufacturers must balance performance, cost, packaging, supply-chain availability, and system requirements.
For example, short-range sensing applications may have different requirements from long-range forward radar.
Therefore, 24GHz radar and 77GHz radar may continue to coexist in different automotive applications rather than one technology immediately eliminating the other.
At the same time, the industry is moving toward higher-resolution radar, multi-channel architectures, advanced antenna designs, and increasingly integrated RF processing.
These trends will create higher requirements for high-frequency PCB technology.
Millimeter Wave Radar PCB Application Scenarios
The applications of millimeter wave radar PCB technology extend beyond automotive electronics.
Two emerging application areas are smart offices and smart homes.
Smart Office Applications
Smart offices increasingly use sensing technologies to improve automation, energy efficiency, safety, and user experience.
Cameras can provide detailed visual information, but camera-based monitoring can also create privacy concerns in offices, meeting rooms, and other semi-private environments.
Millimeter-wave radar offers an alternative sensing approach.
Instead of generating conventional visual images, radar systems can detect movement, occupancy, distance, and other physical characteristics based on reflected electromagnetic signals.
This makes radar attractive for applications where occupancy detection or movement monitoring is required but continuous video imaging may not be desirable.
Potential smart-office applications include:
- Occupancy detection
- People counting
- Presence detection
- Space utilization analysis
- Smart lighting
- HVAC control
- Automated building management
- Contactless interaction
Privacy Advantages of Radar-Based Sensing
Privacy is becoming an increasingly important consideration in intelligent buildings.
A camera can capture identifiable visual information, whereas radar-based sensing can be designed to process non-visual spatial and motion information.
In some applications, radar processing can also be performed locally at the edge device.
Only necessary results, such as occupancy status, movement information, or statistical data, may need to be transmitted to a cloud platform.
This can reduce both privacy exposure and network bandwidth requirements.
However, the actual privacy characteristics depend on system architecture, data processing methods, storage policies, and applicable regulations.
Smart Home Applications
Another important application area for millimeter wave radar PCB technology is the smart home.
Radar can detect human presence and movement without relying entirely on visible light.
This can be particularly useful for applications involving elderly care, home automation, and safety monitoring.
Potential applications include:
- Human presence detection
- Sleep monitoring
- Respiration monitoring
- Heart-rate monitoring
- Fall detection
- Smart lighting
- Air-conditioning control
- Security monitoring
- Automated appliance control
For example, radar-based sensing can help determine whether a person is present in a room and can support automated lighting or air-conditioning control.
Elderly Care and Health Monitoring
Millimeter-wave radar can also be used for non-contact monitoring applications.
Depending on the radar system and algorithm, subtle body movements associated with breathing and heartbeat can be detected.
This creates opportunities for home-based elderly-care systems.
A smart-home radar system may help monitor:
- Presence or absence
- Sleep-related movement
- Respiration
- Heart rate
- Abnormal movement
- Potential falls
Such systems can provide useful information without requiring the person to continuously wear a sensor.
However, radar-based monitoring should be considered a sensing and assistance technology rather than a replacement for professional medical equipment where clinical diagnosis is required.
Radar for Smart Home Automation
Traditional smart-home systems often combine cameras, infrared sensors, motion detectors, and other technologies.
Each sensor has limitations.
Cameras can raise privacy concerns, while conventional infrared sensors may provide limited information about distance, movement, and occupancy.
Millimeter-wave radar can provide additional sensing capabilities.
For example, radar can help determine whether a room is occupied and whether a person is moving within a specific area.
This information can be used to control:
- Lighting
- Air conditioning
- Ventilation
- Home appliances
- Security systems
- Smart curtains
- Energy-management systems
Because radar modules can be compact, they can potentially be integrated into lighting fixtures, appliances, ceiling devices, and other household products.
PCB Requirements for Millimeter Wave Radar
As radar frequencies increase, PCB manufacturing requirements become more demanding.
A high-quality radar PCB should consider several important factors.
High-Frequency Material Selection
Conventional FR-4 materials may not be suitable for every millimeter-wave application.
For high-frequency RF paths, designers may select materials with controlled Dk and low Df to reduce dielectric loss and maintain signal integrity.
Material selection should be based on operating frequency, transmission distance, loss requirements, thermal conditions, and cost.
Impedance Control
Millimeter-wave circuits require carefully controlled transmission-line impedance.
Small changes in trace width, dielectric thickness, copper thickness, or material properties can affect impedance.
Therefore, manufacturing tolerances must be tightly controlled.
PCB Manufacturing Accuracy
At high frequencies, manufacturing variations can have a greater impact on electrical performance.
Important parameters include:
- Trace width accuracy
- Trace spacing
- Layer registration
- Dielectric thickness
- Copper thickness
- Surface roughness
- Via geometry
- Plating consistency
This makes close cooperation between PCB designers and manufacturers essential.
Kingda’s Millimeter Wave Radar PCB Support
For advanced automotive radar PCB and high-frequency applications, Kingda can support projects involving high-frequency material selection, PCB stack-up design, impedance control, precision fabrication, and manufacturing process optimization.
Key considerations can include:
- High-frequency PCB materials
- Controlled impedance
- RF transmission lines
- High-density routing
- Precision layer registration
- Via design
- Copper thickness
- Surface finish
- Manufacturing tolerances
- PCB reliability
For millimeter-wave applications, manufacturing capability should be evaluated during the design stage rather than after the PCB layout has been completed.
Early DFM and engineering review can help identify potential issues related to material selection, stack-up, impedance, routing, and fabrication tolerances.
Conclusion
The development of millimeter wave radar PCB technology is closely connected to the growth of intelligent vehicles, ADAS, smart homes, and smart buildings.
In automotive applications, 24GHz radar and 77GHz radar have different characteristics and application areas. While 77GHz technology offers advantages in bandwidth, resolution, and long-range sensing, 24GHz systems remain relevant for selected short-range applications.
At the same time, advances in SiGe, CMOS, antenna design, signal processing, and RF integration are driving automotive radar toward smaller, more intelligent, and higher-performance systems.
Beyond automotive applications, millimeter-wave radar is also expanding into smart offices, smart homes, occupancy detection, elderly care, and contactless sensing.
As operating frequencies increase, radar PCB design and manufacturing become increasingly important. High-frequency materials, impedance control, precise transmission-line geometry, layer registration, and manufacturing consistency all contribute to the final performance of the radar system.
With the continued development of automotive radar sensors and high-frequency electronics, reliable PCB manufacturing will remain an essential foundation for next-generation radar applications. Kingda can support customers in developing manufacturable, high-quality PCB solutions for demanding high-frequency and millimeter-wave applications.
