Microstrip Ice Detectors
Microstrip lines are now being used to detect the presence of ice on aircraft wings in experiments . Their thinness allows installation at the surface of the airfoil where the ice accumulates without significantly affecting the airfoil shape. Sensor spots are areas of microstrip that are exposed to the environment and depend on a change in local capacitance due to the presence of ice or water. The spots are spaced at open circuit points every half wavelength (about 4 inches for the substrate in use). A 1 GHz signal is fed into the system and the return loss phase and magnitude is used determine when to activate de-icing equipment. A microprocessor corrects the I and Q components to maintain the waveshape along the transmission line so that a constant reference is maintained. This work is being done at the Johnson Space Center in Texas.