Mr.Andrews, the managing director of GAMA Microwave Technology, said it is possible to "tune" the radio-frequencies to provide the best results with any small product.
More data need to be collected to capture higher frequencies, he notes, and this has been a limitation for the relatively small, simple systems used on autonomous subs.
The results show that the sensor has high sensitivity, small hysteresis. The capacitance and impedance of the sensor vary with the relative humidity and the frequencies.