Development and Design of Microstrip Moisture Sensor for Rice Grain

This paper deals with the analysis and design of a microstrip sensor for accurate determination of moisture content (MC) in rice grains. The sensor consists of four layers- RT-Duroid substrate, protective layer, wet medium as a sensing area, and air. A functional relationship has been developed between microwave attenuation of the sensor and moisture content in grains for four layered semi-infinite microstrip structure, and close agreement has been found between computed and experimental results. The analysis of electromagnetic wave propagation in the sensor structure is simply represented and prediction of dielectric properties of rice grains is given by a dielectric mixture model. This work also studies the effect of thicknesses of protective layer on the sensitivity of the sensor. The sensor is suitable for development as a complete instrument and to estimate the optimum moisture content of rice grains, more quickly and accurately