Radar level transmitter NRM

for liquids4-20 mA2-wire

The 2-wire non-contact microwave level transmitters type NRM provide the most advanced, new generation measurement technique of the industrial process automation field, available as NRM-4 (compact version) and NRM-7 (integrated version). Opération Principle The reflection of the emitted microwave impulses is considerably depending on the relative dielectric constant of the measured medium. The essential condition of microwave level measurement is that the relative dielectric constant (er) of the medium should be more than 1.9. The opération of the non-contact microwave level transmitters is based on the measurement of the time of flight of the reflected signais, so-called Time Domain Reflectometry (TDR) method. The propagation speed of microwave impulses is practically the same in air, gases and in vacuum, independently from the process temperature and pressure, so the measured distance is not affected by the physical parameters of medium to be measured. The NRM level transmitter is a Puise Burst Radar operating at 25 GHz (K-band) microwave frequency. The 25 GHz models’ most noticeable advantage over the lower frequency (5-12 GHz) radars are the smaller antenna size, the better focusing, lower dead zone and smaller transmission angle. The level transmitter induces few nanosecond length microwave impulses in the antenna and a part of the energy of the emitted signais reflects back from the measurement surface depending on the measured media. The time of flight of the reflected signal is measured and processed by the electronics, and then this is converted to distance, level or volume proportional data.