The radar level gauge adopts the working mode of transmission-reflection-reception. The antenna of the radar level gauge emits electromagnetic waves. These waves are reflected by the surface of the measured object and then received by the antenna. The time from emission to reception of electromagnetic waves is proportional to the distance to the liquid surface. The relationship is as follows:
D=CT/2

C - the speed of light


In practical application, there are two types of radar level gauges, FM continuous wave type and pulse wave type. The liquid level gauge using frequency modulation continuous wave technology consumes a lot of power, must use a four-wire system, and has complex electronic circuits. The liquid level gauge using radar pulse wave technology has low power consumption and can be powered by two-wire 24VDC, which is easy to achieve intrinsic safety, high accuracy, and wider application range.


1. Ultrasonic accuracy is not as good as radar.
2. Radar is relatively expensive.
3. When using radar, the dielectric constant of the medium should be considered.
4. Ultrasonic waves cannot be used in working conditions such as vacuum, high steam content or foam on the liquid surface.
5. The radar measurement range is much larger than that of ultrasonic waves.
6. Radar has horn type, rod type, and cable type, which can be applied to more complicated working conditions than ultrasonic waves.
We generally refer to sound waves with a sound wave frequency exceeding 20kHz as ultrasonic waves. Ultrasonic waves are a type of mechanical wave, that is, a propagation process of mechanical vibration in elastic media. It is characterized by high frequency, short wavelength, and small diffraction phenomenon. Good directionality, can become ray and directional propagation. The attenuation of ultrasonic waves in liquids and solids is very small, so the penetrating ability is strong, especially in solids that are opaque to light, ultrasonic waves can penetrate tens of meters in length, and there will be significant reflection when encountering impurities or interfaces. The material level is to use this characteristic of it.