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24GHz radar sensor is a type of sensor.
The 24GHz radar sensor can sense the presence, motion speed, stationary distance, and angle of an object by emitting and receiving microwaves with a frequency of around 24.125GHz. It uses planar microstrip antenna technology and has the characteristics of small size, high integration, and sensitive induction. The 24GHz radar sensor is a conversion device that can convert microwave echo signals into electrical signals. It is the core chip of radar speedometers, water level gauges, car ACC assisted cruise control systems, automatic door sensors, and more.
Radar is an electronic device that uses electromagnetic waves to detect targets. Its working principle can be briefly described as: emitting electromagnetic waves to irradiate the target and receiving its echo, thereby obtaining information such as the distance, distance change rate (radial velocity), azimuth, altitude, etc. from the target to the electromagnetic wave emission point.
The commonly used radar operating frequency bands are: 10.525GHz - X-band, 24 GHz - K-band, 35 GHz - Ka band, and 77 GHz - V-band. Among them, 24GHz is a globally recognized radar operating frequency band specified by the ISM code, with minimal interference when operating in this frequency band.
Radar has multiple classification channels
According to the type of radiation source, it can be divided into active radar and passive radar.
Divided by platform; Ground radar, shipborne radar, airborne radar, spaceborne radar, etc.
According to the waveform, it can be divided into pulse radar and continuous wave radar.
According to the working wavelength band, it can be divided into: meter wave radar, decimeter wave radar, centimeter wave radar, millimeter wave radar, etc.
According to the scanning pipeline, it can be divided into mechanical scanning radar and electrical scanning radar. wait.
24GHz radar sensor PCB
The principle of 24GHz radar sensor
1. CW Doppler radar sensor
Select 24GHz as the transmission frequency, and use the frequency difference between the transmitted and received signals to calculate the speed of object motion through a formula. After mixing the reference signal with the echo signal, the dual channel sensor outputs two intermediate frequency signals IF1 and IF2 with the same frequency amplitude and a phase difference of 90 °. Based on the signal type guided by the 90 ° phase, the direction of motion of the object (away or close) can be identified
2. FMCW radar sensor
If you want to measure a parameter [distance], such as the distance from a static object to a sensor, then selecting linear ramp up or ramp down as the time-dependent function of the transmission frequency is sufficient, and regularly repeating these slopes to obtain possible average values. According to the calculation formula of delay effect, the distance of the object can be obtained.
Application of 24GHz Radar Sensor
1. Traffic monitoring
A: Traffic monitoring: vehicle flow, vehicle classification, speed monitoring (police radar)
B: Distance measurement: parking assistance, start stop cruise control, ACC blind spot detection, collision avoidance control, lane change assist system
C: Train application: railway obstacle detection, platform monitoring, shunting assistance, speed testing
D: Rail vehicles: navigation
F: Smart driving
2. Object detection
A: Door opening device
B: Sanitary facilities: faucet, urinal
C: Internal and external intrusion alarms, security management
D: Smart lighting
E: Counting device
3. Sports applications
24GHZ radar sensor
24GHZ radar sensor
A: Distance and speed measurement in sports such as running, skiing, surfing, etc
B: Ball speed measurement
4. Industrial applications
A: Liquid level measurement
B: Flow velocity measurement
C: Mud density measurement
D: Conveyor belt monitoring
E: Robot
24GHz microwave radar sensors are widely used in fields such as active vehicle safety, intelligent transportation, safety prevention and protection, industrial applications, and drone collision avoidance. On the other hand, radar sensors need to cover appropriate areas.
The commonly used 24GHz receiving antenna modes by manufacturers include microstrip array receiving antennas, horn receiving antennas, dielectric substrate integrated waveguide receiving antennas (SIW), and lens receiving antennas. Considering the size and manufacturing issues of radar sensors, the most popular receiving antenna in the commercial field is microstrip receiving antenna. Microstrip receiving antenna printed on high-frequency PCB. With the help of mature PCB processing technology, radar sensor manufacturers can greatly reduce costs.