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As a non-contact sensor, the millimeter wave radar has the advantages of accurate sensing, no interference. It is now widely used in the ADAS (Advanced Driving Assistant System) in the automatic driving area. However, with the development of the market, the scope of application of millimeter wave radar is outside the vehicle field, gradually expanding to smart cities, building automation, health monitoring, and other industries.
Millimeter wave radar
Marketsand Markets recently released data show that by 2023, the total market in millimeter Pod Sensors will reach $ 20.6 billion. Car radar is the main driving force of this wave of growth, but the Internet of Things market will become another wheel that drives the millimeter wave radar market.
The propagation attenuation in the atmosphere is severe, and the device processing accuracy requirement is high. Millimeter waves are smaller when they use the atmospheric window to spread, which has little affected on natural light and thermal radiation sources. When the millimeter wave is propagated in the atmosphere during the atmosphere, some attenuation caused by gas molecular resonance is a very small frequency. To this end, they have significant significance in communication, radar, guidance, remote sensing technology, radio astronomy, and spectral. The millimeter wave frequency of the atmosphere can achieve large-capacity satellite - ground communication or ground relay communication.
Millimeter wave radar in automatic driving
The millimeter wave frequency of the atmosphere can achieve large-capacity satellite-ground communication or ground relay communication. The narrow beam and low sidewire performance of the millimeter wave antenna can achieve low elevation angle precision tracking radar and imaging radar. When the remote missile or spacecraft returns to the atmosphere, it is necessary to use millimeters of millimeter waves that can smoothly penetrate the plasma to achieve communication and guidance. High-resolution millimeter wave radiometer applies to the remote sensing of meteorological parameters. The radiation spectrum of the universe space can be used to infer the ingredient of the interstellar substance with millimeter wave and mm-wave.
The advantages of millimeter wave radar have the following points:
1 Small antenna caliber, narrow beam: high tracking and guiding accuracy; easy to carry out low elevation angle tracking, anti-ground multipath and clutter interference; high-level resolution on the near-air target; high-angle resolution for regional imaging and target monitoring ability; high-resistance interference performance of narrow beam; high antenna gain; easy to detect small objectives, including power lines, poles, and projectiles.
2 Large bandwidth: High information rate, easy to use narrow pulse or broadband frequency modulation signal to obtain detail structural features of the target; wide expanded ability, reduce multipath, clutter, and enhance anti-interference ability; radar of adjacent frequencies Or millimeter wave identifier work, easy to overcome mutual interference; high-distance resolution, easy to get accurate target tracking and identification ability.
3 High Doppler frequency: good detection and recognition ability of slow objectives and vibration targets; easy to use target Doppler frequency characteristics to target characteristic identification; penetration characteristics of dry atmospheric contamination, provide in dust, smoke, and good testing capabilities under dry snow conditions.
4 Good anti-blanking performance: The absorbing materials coated on the current stealth aircraft are targeting centimeter waves. According to the research, the stealth target of millimeter wave radar can form a plurality of strong electromagnetic scattering, so that the stealth performance is greatly reduced, so millimeter wave radar also has an anti-stealth potential.
Cars have always been an important entry point for millimeter wave radar in the development of civilian fields. With the rise of automatic driving, the development momentum is very strong. L2 is currently a standard in the automatic driving system. However, the application range of millimeter wave radar is not limited to the car. Smart transportation, smart home, security, rail transit, drone, etc. are the potential market for millimeters, in which the intelligence traffic, the security field has formed a certain size market, and the wisdom home field is also an important potential market.
Millimeter wave radar
Taking traffic monitoring as an example, many large cities are currently facing traffic jams. One of the solutions is to more accurately control the traffic lights on the crossroads and the main roads. 4D millimeter wave radar is a multi-lane multi-object tracking device designed for intelligent transportation systems, providing accurate X, Y, Z three-dimensional coordinates and one-dimensional speed of 4D multi-objective real-time tracking traces and traffic flow basic information such as traffic, lane share, model, queuing length, and event analysis.
If we integrate 4D millimeter wave radar on a high-definition video camera, it can simultaneously monitor 4 to 12 lanes and provide 128 targets high-resolution four-dimension radar trajectory information, and synchronously overlapping it on video. With this information, people can adjust the traffic lights more effectively to make the traffic become smooth.
Application cases in millimeter wave radar in the field of the smart home are also increasing. With the acceleration of the aging process, millimeter wave radar and wisdom endow have evolved a lot of new use of a falling alarm, sleep monitoring, etc. Millimeter waves can also detect subtle objects, such as human gestures, breathing and heartbeats. Medical is using millimeter wave radar to explore more application scenarios, such as blood pressure monitoring, emotional monitoring, etc.
Millimeter wave radar does not require optical imaging, you can track a person's activities, and detect people's activities, including sports features such as personnel, without worrying about the privacy issues brought by using the camera.
If you divide the working band, millimeter wave radar for the civil market has roughly three types - 24GHz millimeters, 77GHz millimeter wave radar, and 60GHz millimeter wave radar. So, which operating frequency section is more suitable for the development of non-car markets?
24GHz millimeter wave radar is the first to put into civilian wave radar, with a wavelength of 1.25cm. Since the frequency of the frequency band is relatively low, the bandwidth is relatively narrow (only 250 MHz), so the 24 GHz millimeter wave radar is limited in measurement accuracy, which also limits its application range. However, due to the maturity of 24GHz, it is cheap.
The millimeter wavelength of the 77GHz band is only 3.9mm, the frequency is relatively high, with a bandwidth of 4GHz. In general, the shorter the wavelength of radar, the higher the resolution/accuracy. And the outer shape of the entire system will be smaller. Therefore, 77 GHz millimeter wave radar gradually picked 24GHz products in the market, which became mainstream in the automotive field, and many countries and regions also assigned this band as a special frequency band of automobiles. With the maturity of 77 GHz millimeter cable technology, the cost-effective advantage of the 24GHz program is not so significant.
The 60GHz mm radar wavelength is 5mm, which has a use of up to 7GHz for short-range applications, so it can provide better resolution. Its appearance is mainly in order to cope with 24 GHz radar bandwidth, insufficient precision, and have limitations of the sensing of objects. Because of this, all major technology vendors compete around millimeters in the non-automotive sector, and gradually transfer from 24GHz to 60GHz.
60GHz band is expected to become mainstream of the market of intelligent homes, health monitoring, and other indoor applications. The 60GHz band is an atmospheric absorption window, which is very suitable for the close-up. There is currently a variety of this band chip and module to enter the commercial phase.
As for the millimeter-wave radar in smart traffic, due to high-performance requirements (such as detection distances or even more than 500 meters, the detection accuracy, and resolution ability are highly required), the corresponding products have been taken from 79g to 81GHz.
In the non-automotive field, the future performance of millimeter wave radar is worth looking forward to. Currently, many domestic and foreign mainstream manufacturers have corresponding product development in the 60 GHz band. A scalable 60GHz single-chip millimeter wave sensor developed by Texas Instruments enables reliable contact gesture detection, such as light control, media control, etc. The 60GHz microwave antenna for UNDON is integrated with radar gesture recognition sensors, which can be applied directly on the phone or wear device. Google has released a 60GHz millimeter wave radar chip, which can be easier to track and analyze sleep quality.