Microwave-Based Moisture Estimation by Scanning for Paddy Inspection

Microwave at 2.45 GHz frequency has been found to resonate in water and may attenuate on a straight line between a transmitter and receiver according to the water volume. The level of microwave attenuation is known to be used for moisture measurement on a point-to-point line inside an object. To measure moisture volume in an object in any shapes, it is required to install many antennas as moisture sensors which need to cover all areas of an object, and attenuation level obtained from all sensors are summarized for calculating total moisture of the object. This paper proposes a method to design a microwave-based moisture estimation system by using scanning with a sensor. Theoretically, the total moisture in the object can be sensed attenuation by moisture sensors installed covering an object, and attenuation obtained from all sensors is calculated into percentage of moisture in the object. This paper utilizes a moisture sensor to scan on a plane covering an object. All attenuation obtained from the moisture sensor which is scan on a plane shall calculate the average moisture on behalf of using many moisture sensors. To evaluate the performance of proposed method, experiments and simulations in water and paddy in a few container shapes have been performed, and the results confirmed its effectiveness.