Abstract:
An icing sensor utilizes a surface gap transmission line along which a radio frequency is transmitted. The phase delay of the radio frequency along the transmission line is dependent upon the dielectric constant presented at the surface in the gap between the transmission line electrodes. Accordingly, changes of dielectric constant affect phase delay of the transmitted frequency. This phase delay may be used to detect the difference between ice, water and snow as well as the presence of freezing point depressing fluids such as ethylene glycol. When the sensor is mounted on an aircraft control surface, the presence and likelihood of icing conditions may be predicted. Through the use of one or more temperature, freezing point depressing fluids/water mixture determined from dielectric constant, and rate of change of the dielectric constant, it is possible to predict the time delay until icing begins. Thus, the sensor of the present application may safely reduce the effort and expense in aircraft deicing.