solids or sludge) inside tanks, silos or cisterns or to monitor the water level in wells, canals or in any place where the absence of moving parts under water is required. This allows for a very simple installation and at the same time a high quality measurement. The meter works by using the technology of high frequency electromagnetic waves (microwaves), which travel at the speed of light. The radar sensor sends microwave pulses towards the surface of the material to be measured. When the wave reaches the surface of the material, it is reflected back towards the sensor. The amount of reflected signal depends on the nature of the material and its dielectric constant (the higher it is, the better it reflects). The sensor receives the return signal and measures the time taken by the wave to go and return. Knowing the speed of light, the device calculates the distance between the sensor and the surface of the material. The level of the material is then calculated by subtracting the measured distance from the total height of the tank. The output signal is in mA and is directly proportional to the distance between the sensor and the water surface: where 4mA is the maximum height and 20mA is the minimum. Every sensor is provided with a calibration certificate that attests the results of the test performed and all electromechanical features.