Friends familiar with millimeter wave radar technology know that the frequency band of this radio technology is 30-300GHz, and currently the main frequency bands used are 24GHz, 60GHz, and 77GHz. In the article "What are the similarities and differences between domestic and international standards for millimeter wave radar frequency bands?", the author also briefly summarized the standards and specifications for frequency bands used at home and abroad.

Friends who are familiar with the industry will know that the development of high-frequency technology is the direction that many enterprises are planning. At present, major manufacturers of microwave radars (5.8GHz, 10.525GHz) have started testing and shipping products in higher frequency bands (24GHz, 60GHz); Many manufacturers who once focused on 24GHz radar are also moving towards the 80GHz and 94GHz frequency bands.

So, with the development of the industry in the future, will millimeter wave radar "roll" into the field of>100GHz? In fact, manufacturers have now released radar chips of 120GHz, 240GHz, and 300GHz on the market.

Next, this article will briefly explore the application and product situation of>100GHz radar.

It is worth mentioning that radar with frequencies greater than 100GHz is also known as terahertz (THz) electromagnetic waves. And terahertz (THz) waves refer to frequencies ranging from 0.1 to 10 THz (wavelengths from 3000 to 30 μ m) Electromagnetic waves within the range coincide with millimeter waves in the long wavelength range and with infrared light in the short wavelength range
（Note: millimeter wave naming depends on the wavelength, terahertz naming depends on the frequency band, the two have crossover, do not conflict)

Application of terahertz radar

Before discussing the application of terahertz radar, it is necessary to briefly compare the similarities and differences between this type of radar (taking 120GHz radar as an example) and 24GHz, 60GHz, and 80GHz radars.

The first is the 24GHz radar, which has a lower radiation frequency and is suitable for measuring relatively dense media. Its range is generally short, and its application range is usually below 30 meters, but its accuracy is relatively high. Moreover, the 24GHz radar electronic movement module has strong anti-interference performance and is suitable for working in vibration or electromagnetic interference environments. Therefore, 24GHz radar is widely used for solid changes such as cement, powder, coal ash, and liquid tank level measurement, and is also suitable for applications such as security and vehicle mounted BSD.

Next is the 60GHz radar, which has a higher radiation frequency and is suitable for measuring substances with sparse media and smaller particle sizes. It has a relatively long range, up to about 100 meters, and can measure substances with larger depths. At the same time, the 60GHz radar electronic movement module adopts advanced digital signal processing and high-speed ADC technology, making it more accurate and able to achieve high-speed and accurate measurements. Therefore, 60GHz radar is suitable for measuring rivers, reservoirs, well depths, material ranging, and other fields. Currently, more companies are using it in areas such as human presence and motion sensing.

Once again, there is a 77GHz radar, which has a higher radiation frequency. Due to its high RF energy, it can penetrate the absorption layer and reflection curve inside the measurement medium, ensuring the accuracy of the measurement results. In addition, the signal strength of the 77GHz radar is high, and it has stronger anti-interference ability. Therefore, 77GHz radar is suitable for applications such as transportation, 4D imaging, road gates, drones, and other vehicle level or higher requirements.

Finally, the 120GHz radar, due to its longer measurement distance and larger range (up to around 200 meters), can measure objects such as deep wellheads and distant distances. At the same time, the 120G radar overcomes the reflection problem in traditional radar measurement, improves the accuracy of signal processing, makes the measurement results more accurate, and has higher resolution.

In theory, 120GHz radar can be widely used in various industrial, medical, maintenance and operation scenarios, such as high-precision level/liquid level gauges, production line robotic arm environment collision avoidance perception, high-precision positioning, liquid product bottle depth measurement, non-contact and non-infectious vital sign detection in surgical rooms, DNA analysis, drone detection sensors, and so on. However, there are currently few practical applications, mainly used for measuring the liquid level and depth of large tank bodies, as well as irregularly shaped materials such as cement, coal ash, peanuts, soybeans, etc.

Generally speaking, the advantage of implementing a radar system in the terahertz frequency band is that it can obtain higher bandwidth, resulting in more accurate range resolution. Currently, commercial millimeter wave radar chips mainly focus on the 24, 60, and 77GHz mentioned above, with bandwidths of around 1, 4, and 5GHz, respectively. The theoretical range resolution ranges from a few centimeters to more than ten centimeters, suitable for scenarios such as in vehicles, intelligent transportation, intelligent buildings, and smart homes, But in many industrial testing fields, its accuracy level cannot meet the requirements. Moreover, in addition to the aforementioned scenarios, terahertz radar is also a key area worth exploring in the field of biomedicine.

So, moving towards the terahertz frequency band is a major trend in millimeter wave radar. So, what companies are currently laying out and what products are worth mentioning?

Products of terahertz radar

At present, there are already many companies in the 120GHz market layout.

From the upstream chip side, the SiGe process 120GHz radar chip launched by foreign company Silicon Radar GmbH (acquired by Indie on February 22, 2023) has been widely used in various domestic liquid level gauge products. The company has recently launched the industry's highest bandwidth single chip terahertz radar, which is a 120GHz (25GHz bandwidth) radar chip and a 300GHz (40GHz bandwidth) radar chip, with a resolution of 3-6 millimeters.

Meanwhile, domestic enterprises have already released products, and Microelectronics has now launched a 160GHz (13GHz bandwidth) CMOS terahertz radar chip. This product has been validated as early as 2021, and there were also reports that the company's 240GHz radar chip was under design.

From the perspective of terminal manufacturers, there are currently products such as Luda, Nupu Xin Technology, Zhongyi Zhilian, Fuzhou Shengbo Electronics, etc., which have released products including 120GHz ranging radar, level gauge, liquid level gauge, etc.

With the development of the times, radar products will inevitably iterate towards higher accuracy and resolution, and terahertz radar products will have the opportunity to become a major trend in the future. For the millimeter wave radar industry, this means that there will be more room for evolution of related products in the future, and enterprises can have more choices in layout.

However, in practical applications, the current application of millimeter wave radar is mainly in the 24GHz, 60GHz, and 77GHz frequency bands. Although terahertz radar is technically and theoretically feasible, it still needs to be driven by the overall ecology.