Radar Level Transmitter Principle

Radar technology is mainly put into use for detection of level in continuous level measurement applications. Radar level transmitters provide non contact type of level measurement in case of liquids in a metal tank. They make use of EM i.e. electromagnetic waves usually in the microwave X-band range which is near about 10 GHz. Hence, they can be also known as microwave level measurement devices.

However there are some differences between radar and microwave types. They are:

  1. Power levels in case of radar systems are about 0.01 mW/cm2 whereas in case of microwave systems, these levels range from 0.1 to 5 mW/cm2.
  2. Microwaves can work at higher energy levels; hence they are competent enough to endure extra coating as compared to radar level detectors.

A radar level detector basically includes:

  1. A transmitter with an inbuilt solid-state oscillator
  2. A radar antenna
  3. A receiver along with a signal processor and an operator interface

The operation of all radar level detectors involves sending microwave beams emitted by a sensor to the surface of liquid in a tank. The electromagnetic waves after hitting the fluids surface returns back to the sensor which is mounted at the top of the tank or vessel. The time taken by the signal to return back i.e. time of flight (TOF) is then determined to measure the level of fluid in the tank.

Radar fill level transmitters, use radio wave emissions just like radars. Usually, these devices are mounted at or near the top of a tank filled with a liquid. The transmitter itself sends out a radar signal into the liquid in the tank and receives a reflection of that signal. The transmitters will then accurately calculate the current fill level of the tank based on how long it takes the transmitted signal to return.

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