A Microwave Attenuation Comparator as an Industrial On-Line Moisture Controller

The circuit of a moisture content - attenuation - voltage converter in the form of a microwave attenuation comparator is presented in the paper. Time-domain discrimination of the measuring and reference signals has been applied. Independence between the measurements results and the phase relations in the sensor as well as the microwave elements parameters unstability has been assured. A special direct-coupled d.c.amplifier has been interconnected between comparators output and signal level meter. A 0,001 dB resolution and 0,01 dB long-term stability within a measured attenuation range of 20 dB has been achieved.