What is a Radar Level Sensor?

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 measurement.

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.
what is a radar level sensor?, radar level sensor working principle

Propagation of Radar Electromagnetic Waves

  • Speed of electromagnetic waves is 300,000,000 m/s
  • Influence of temperature, pressure and humidity can be neglected
  • Conductive materials and materials with a different dielectric constant than air give reflections

Learn more about ABM’s non-contact radar level sensors here.

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