Radar water level sensor is the ideal solution for measuring the water level in dams, ponds, rivers, reservoirs, etc.

SIRD-908 Radar Water Level Sensor

Radar water level sensor is Non-contact water level sensor, for long term surface water measurements. SIRD-908 Radar Water Level Sensor adopts a transmitting frequency up to 26GHZ. The antenna is made of corrosion-resistant materials such as stainless steel and PTFE. It is suitable for measuring the height of the liquid level of rivers, lakes, reservoirs, and groundwater media. The maximum distance can reach 30 meters. Output 4- 20mA or RS485 signal.

Sino-Inst offers a variety of Frequency modulated continuous wave radar for industrial level measurement. If you have any questions, please contact our sales engineers.

Features of SIRD-908 Radar Water Level Sensor

  • All-weather work. 26GHz microwave reflection principle, strong anti-interference ability.
  • The sensor has a reliable accuracy of 3 mm.
  • No mechanical wear, non-contact measurement. Long life and easy maintenance
  • The measurement has nothing to do with water quality. It is not affected by floating objects such as floating ice
  • No need for wave wells. No effect on water flow
  • Unattended continuous online collection
  • Ultra-low power consumption. Support solar power supply
  • It can be used for wireless network transmission. No need to excavate cable trench. It has no impact on the construction of channel lining and tree planting.
  • Low cost. Simple installation and maintenance. Long life.

Specifications of SIRD-908 Radar Water Level Sensor

Application:Rivers, lakes, shallows
Measuring Range:30 meters
Process Connection:Thread G1½ʺ A / bracket / flange
Process  Temperature:-40~100℃
Process Pressure:Atmospheric
Protection Grade:IP67 / IP65
Frequency Range:26GHz
Supply:DC (6-24V) / four wire DC 24V / two wire
Signal Output:RS485/Modbus protocol 4~20mA/Hart two wires
Housing: Aluminum single cavity / aluminum dual cavity /
plastic / stainless steel single cavity
Explosion-proof Grade:Optional

Radar Water Level Sensor working principle

Measuring principle:

Micro-power microwave pulses are emitted from the radar antenna and travel through space at the speed of light. It is reflected by the object to be measured and received by the radar.

The time difference between the transmission and reception of the pulse signal is proportional to the distance from the radar antenna to the measured object. The propagation speed of electromagnetic signals in space is the speed of light. Usually when measuring the distance, the time difference between the transmitted pulse and the received pulse is very short and only on the order of nanoseconds.

Conventional technology is difficult to accurately measure this time.

SIRD-908 Radar Water Level Sensor uses an advanced equivalent sampling method to accurately measure the original nanosecond time interval. So as to realize the accurate measurement of distance.


The extremely tiny 26GHz radar signal is emitted in the form of short pulses from the antenna end of the radar level gauge.
The radar pulse is reflected by the sensor environment and the surface of the object and received by the antenna as a radar echo.
The rotation period of the radar pulse from emission to reception is proportional to the distance, that is, the level.

◆ Input
The antenna receives the reflected microwave pulse and transmits it to the electronic circuit. The microprocessor processes this signal. Identify the echo generated by the microwave pulse on the surface of the material.
The correct echo signal identification is completed by intelligent software, and the accuracy can reach millimeter level. The distance D from the surface of the material is proportional to the time travel T of the pulse:
Where C is the distance of the empty tank at the speed of light E is known, then the distance of the level L is: L=E-D

◆ Output
It is set by entering the empty tank height E (=zero point), the full tank height F (=full scale) and some application parameters. Application parameters will automatically adapt the meter to the measurement environment. Corresponds to 4-20mA output.

Extended reading: Amazing Solutions for Continuous Liquid Level Measurement

Radar Water Level Sensor Applications

  • River water level, automatic monitoring of open channel water level, water resource monitoring and water level measurement;
  • In front of the reservoir dam, the tail water level monitoring and surge tower (well) water level monitoring below the dam;
  • Automatic tide level monitoring system, urban water supply and sewage level monitoring system;
  • Mountain flood warning system water level monitoring, water level monitoring of small and medium rivers.

Extended reading: Capacitive water level sensor

Using the principle of radar wave reflection, the time required for transmission and reception can be converted into liquid level height or distance. This is a method often used in the field of liquid level monitoring. This non-contact method is stable and reliable, so it is widely used.

In the past, river water level monitoring generally used manual field measurements to obtain data. Although this method is reliable, it also has many problems, such as:

(1) There is a certain risk of manual field measurement on the river bank (the river is 5 meters deep).
(2) Do not stop working in bad weather.
(3) The measured value is not very accurate and can only be used as a reference.
(4) The labor cost is high, and field data records need to be performed many times a day.

Install radar water level gauges in the reservoir area to monitor water level changes. In the water level monitoring of many reservoirs, the radar water level gauge is selected to monitor the water level change, mainly considering that the radar water level gauge has the water level measurement value that is not affected by the weather and air pressure changes.

Moreover, the observation values ​​are accurate and the observation data are stable, and the depth of the observation water level is usually 30-50 or more.

To accurately measure the water level of river cofferdams and dams, ultrasonic liquid level sensor/radar water level sensor is used to accurately monitor the water level before and after the grid in real time.

Place the ultrasonic liquid level sensor/radar water level sensor bracket on the water surface. The signal can be sent to the PLC for processing of the collected amount.

And send the real-time water level and differential pressure data to the central control room, display and alarm over limit.

At the same time, the RS485/RS232 interface is adopted, and the real-time data is sent to the industrial computer in the centralized control room of the dam, and processed into computer communication messages,

Finally, the collected amount will be sent to the upper computer of the computer monitoring system of the power plant. This technology is widely used in many hydropower stations.

Read more about: Hydrostatic Submersible Level Transmitter-Straight Rod Insertion

Extended Reading: 3 inch (3″) Water Flow Meter

More Water Level Sensors

Sino-Inst offers a variety of water level sensors for a wide range of conditions. Our sensors are ideally suited for monitoring water levels in streams, dams and reservoirs. Our water level sensor products include:


The radar level sensor uses ultra-high frequency electromagnetic waves to transmit to the liquid level of the detected container through the antenna. When the electromagnetic wave hits the liquid level, it is reflected back. The instrument detects the time difference between the transmitted wave and the echo, thereby calculating the height of the liquid level.
The better the conductivity of the measured medium or the greater the dielectric constant, the better the reflection effect of the echo signal.

First of all, the radar level meter can definitely measure the water level. Please use it with confidence.

Again, consider how much the measurement range is. If it is a short range, there is no need to use it, it is too wasteful and the cost is too high.

If you want to use it well, the short-range magnetostrictive liquid level sensor is economical and has better accuracy than radar in all aspects.
If you want to reduce costs, the submersible hydrostatic level sensor is suitable.

Common water level sensors can be used for water level.

There are many types of water level sensors, so their specific measurement principles are different.
If you need to learn more. You can refer to:
Differential pressure type liquid level measuring instrument;
Float level measuring instrument;
Electric liquid level measuring instrument;
Ultrasonic liquid level measuring instrument;
Radar liquid level measuring instruments, etc.

Extended reading: Capacitive water level sensor

Among the many water level sensors, contact measurement is required: submersible hydrostatic pressure level sensors, differential pressure level transmitters, float level sensors, magnetostrictive level sensors, and capacitive level sensors. You can learn how they work separately.

The river water level monitoring system is intended to monitor the water level scientifically and effectively. In order to prevent the water level from being too high or too low, it is an important means to prevent flood disasters.

The system is mainly composed of radar level gauge, solar power supply system, GPRS wireless transmission and other equipment. It has the functions of collecting information, data analysis, over-water level alarm, and predicting water level. It is a good helper for the government and flood control departments, effectively reducing people’s property losses.

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Sino-Inst offers over 10 Radar Water Level Sensors for level measurement. About 50% of these are Radar level meters, 40% is the tank level sensor.

A wide variety of Radar Water Level Sensor for level measurement options are available to you, such as free samples, paid samples.

Sino-Inst is a globally recognized supplier and manufacturer of Radar Water Level Sensor instrumentation, located in China.