mmWave Radar Sensor ModulesTechnical features of mmWave radar and a comparison with other sensors

Millimeter waves offer a wider available bandwidth compared to microwaves. Because the resolution becomes smaller in the range direction as the bandwidth widens, this allows two objects with smaller widths to be separated. For example, in a 79 GHz band with a 4 GHz bandwidth, the theoretical range resolution is 3.75 cm.

Radio waves with short wavelengths in the mmWave band can propagate on a larger scale than fine particles such as rain, fog, and dust. This means that the effects of scattering and absorption by these fine particles are comparatively small, reducing radio wave attenuation and enabling detection that is not affected by weather as a result.

The size of the circuits and antennas in devices that utilize radio waves is proportional to the wavelength. Since mmWaves have a shorter wavelength than microwaves, this makes miniaturization and integration easier in circuit and antenna design.

Infrared sensors use infrared rays that have a longer wavelength than visible light. Passive infrared sensors detect the infrared rays from the body heat of humans or animals to detect movement. Active infrared sensors transmit their own infrared signals and use methods for receiving the reflected waves to receive signals that hit an object and detect the distance or object.

Ultrasonic sensors use high-frequency sound to detect the presence of and distance to a target. Since ultrasonic waves propagate at a constant speed through air or water, the distance can be calculated by using the time it takes for the transmitted sound waves to reflect back from the object.

LiDAR (Light Detection And Ranging) uses laser light to sense the distances of objects. It emits laser light at a target and receives the reflected light to calculate the distance from the time it takes for the emitted light to return. The relative speed can also be measured using the Doppler effect. In addition, it is also possible to emit multiple laser beams and receive the reflections at high speed to understand 3D shapes from multiple sets of data.

Camera sensors convert light into electrical signals to turn visual information into digital data and reproduce that information in high resolution. They primarily use CMOS and CCD sensors to convert light into electrical signals. They detect color information based on light intensity and color filters.