What is a Radar Level Sensor?
A radar level sensor is a device that uses radar technology to measure the level of a substance, such as a liquid or solid, in a container, tank, silo or bin. It is a continuous level measurement device that provides real-time, non-contact level monitoring.
Radar Level Sensor Working Principle
The basic working principle involves transmitting a burst of electromagnetic waves (microwaves) from the sensor and measuring the time it takes for the waves to travel to the target and back. The time-of-flight is then used to calculate the distance.
Here is the step-by-step process:
- A radar electromagnetic burst is transmitted and directed by a dielectric rod antenna or metal horn antenna.
- The electromagnetic waves (microwaves) propagate toward the surface of the target and then reflect back towards the sensor.
- The reflected waves are received by the same antenna and converted to an electrical signal.
- The electrical signal is amplified and processed.
- The sensor measures the time it takes for the emitted waves to travel to the material surface and back using time-of-flight principle.
- The microprocessor in the sensor calculates the distance to the target using the speed of light, a known variable, and the round-trip time as shown in the following equation:
- Distance = Time x Speed / 2
- Where division by two is required as time measurement is round-trip (to the target and back)
- The calculated distance is converted linearly to 4 mA to 20 mA current. Optionally, information can be sent via RS232 or RS485 to a PC for processing such as diagnostics, programmable set-up and data logging.
- The distance measurement is then used to determine the level of the substance in the tank.
When to use Radar Sensors
Radar level sensors are ideal for continuous level measurement of liquids and solids in challenging environments that have vapour, gases, temperature variations, extreme temperatures, extreme dust, wind, foam, ice or acoustic noise.
Propagation of Electromagnetic Waves
- Microwaves do not need a medium to travel, they can travel in a vacuum
- Speed of electromagnetic waves is 300,000,000 m/s
- Electromagnetic waves are not effected by temperature, pressure or humidity
- The reflection depends on the dielectric constant of the liquid or solid material
- The higher the dielectric constant, the better the reflection. As an example, water has a dielectric contact of ~80 where as plastic pellets have a dielectric constant of ~1.5
Types of Radar Level Sensors
There are several types of non-contact radar level sensors available, each suited to different applications, environments or the material being measured.
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Solids Radar Level Sensor R-SLD
Radar Sensors -
Fast Response Radar Level Sensor R-FR
Level Sensors -
Flood Monitoring Radar Level Sensor R-FM
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Oil-Water Interface Detection Radar Sensor R-ID
Radar Sensors -
Anti-Collision Radar System R-AC
Radar Sensors -
Wireless Remote Radar Level Sensor R-RMB
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Liquid Radar Level Sensor R-LIQ
Radar Sensors -
Remote Radar Level Sensor R-RM
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Sanitary Radar Level Sensor R-SAN
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Explosion Proof Radar Level Sensor R-EXP
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High Temperature Radar Level Sensor R-HT
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High Pressure Radar Level Sensor R-HPR
Radar Sensors