Microwave Measurements of Moisture Content of Aggregate

An instantaneous method for measuring the moisture content in aggregate such as sand is developed using a microwave open-ended coaxial cavity resonator. We measure the attenuation and frequency shift of resonant peaks of the cavity resonator, which are related to the moisture content of the sand. The standard deviations in the attenuation and frequency shift are 0.30% and 0.14% in the percentage of moisture, respectively. The frequency shift measurement is better than the attenuation measurement to calculate the moisture content.