Fast Moisture Profile Mapping of a Wet Paper Web with a Dual-Mode Resonator Array

A sensor array for measuring water mass per unit area of wet paper web has been constructed. The sensors are stripline resonators with two center conductors and two resonance modes, even and odd. By measuring the resonance frequency difference of these modes several disturbing factors can be partly compensated, for example air humidity and temperature, sensor temperature and vertical location of the paper web in the sensor. An overall water mass per unit area measurement accuracy of 0.5 % has been estimated for the array.