A Study on the Detection of the Rain Using Open-Ended Coaxial Cavity Resonator

This paper is a study of a rain sensorusing an open-ended coaxial cavity resonatorwhich senses the amount of rain drops linearly. It shows that it will be used as a sensor to sense the amount of rain dropped on the windshieldof an automobile based on the principle of varied resonantfrequency and the loss according to the amount and characteristics of an dielectric lied on the open side of a resonator. The input and output ports are built in the both sides of the resonatorand the input and output coupling probes are formed like `ㄱ` shape. The response of rain drops were simulated by the radius of inner conductor of 2 mm, 5 mm, and 10 mm respectively and it showed that the raindrop was sensed most linearly and sensitively when the radius of inner conductor is 5 mm, We have measured that the resonantfrequency have varied from 3.55 GHz to 3 GHz and the Q valuehave varied from 42.38 to 24.3 according to the variation of rain drop amount on the fabricated resonator. Therefore, it shows that the designed resonatorcan be applied as a rain sensorthat measures the amount of rain drops linearly by using the resonantfrequency as a measurement parameter.