Atmospheric Icing Sensors - Capacitive Techniques

Abstract

The application of capacitive sensing technique is widely distributed in different physical domains primarily because of the diversity in dielectric permittivity and due to its minimum loading error and inertial effects. Atmospheric ice is a complex mixture of water, ice and air which is reflected in its complex dielectric constant. There are many existing atmospheric icing sensors but only few are based on their complex dielectric permittivity measurements. This technique is very suitable because the capacitive variation in this mixture is due to the reorientation of water dipole in the electromagnetic radiation's oscillating field. Depending on the frequency, the dipole may move in time to the field, lag behind it or remain apparently unaffected. This variation is clearly reflected on the Cole-Cole-diagram, which is a measure of the relaxation frequency. This paper is a detailed understanding of some capacitive sensing techniques in general but based upon dielectric variations and some existing capacitive based atmospheric ice sensing techniques. It is emphasized that the capacitive method proposed by Jarvenin provides maximum atmospheric icing parameters hence future atmospheric icing sensors may utilize the proposed technique with some modifications to further reduce the loading errors.