Microwave technology is the basis for microwave moisture analyzers that are being used in various fields. This can work in two ways such as by transmission or by reflection or resonance for measuring the moisture content of various types of samples.
The technology by reflection or resonance means that the microwave is radiated into the sample bed and the evaluation is made on the microwave frequency that is reflected from the sample to be analyzed. This technology is restricted to evaluating the free or surface moisture of the sample.
Although some deem that bound moisture is also calculated using microwave moisture analyzers, this is only accurate for samples with a very low dilution or attenuation factor such as grain. This refers to any reduction or lessening in the strength of the signal.
The reflection technique, on the other hand, fails to be a reliable bulk moisture analyzer for samples with a high attenuation because it can only measure the microwaves that penetrate a thin surface layer of the sample. This is particularly important for samples where penetration of microwave will be at best of the order of a centimeter.
The frequency of resonance of the microwave field is diminished and detuned based on the sample’s water content. The variations in the frequency of microwave are measured by the antenna receiver and this signal is then analyzed by the integrated microprocessor-based control unit.
The measurement of the parameters mentioned above and their assessment makes it possible to verify separately the moisture content as well as the material density.
Microwave moisture analyzers like the DSC Moisture Wave Microwave Moisture Analyzer™ work on the theory that water has a very higher dielectric constant, unlike other materials.
When microwaves interrelate with the molecules of water within the sample, they slow down and later change phase before attenuating as the energy is shifted to the water.
A low profile antenna sends outa beam via the sample directly on the conveyor belt. The signal or frequency is established by a built-in receiver antenna positioned below the conveyor belt.
Microwave Moisture Analyzers provide faster test time compared to conventional moisture balance. Operating based on the LOD concept, this type of analyzer is ideal for high volume testing or when the obtainability of the results is required at the shortest possible time. Other brands of moisture analyzers using the microwave technology include CEM, Omnimark, Denver Instruments, Prekeem, and Sartorius.
