Non-destructive Moisture Content Testing for Soil Brick Using Capacitive Measurement With 50 MHz Radio Frequency

Abstract

This research paper presents a soil brick moisture measurement by capacitive measurement with radio frequency of 50 MHz and the soil brick as the dielectric material sandwiched between the conductive plates of the capacitor. The moisture content of the soil brick was considered from the capacitance storage capacity of the capacitor. The proposed measurement consisted of a voltage-controlled oscillator, capacitance measurement circuit, radio frequency amplifier, radio frequency detector, and microcontroller unit. After that, a circuit was built and assembled to the radio frequency soil moisture meter of soil bricks for evaluate the soil brick with width of 20 cm, length of 40 cm and the thickness of 20 cm. There are four types of soil brick with moisture of 10% to 30% and 10 times of iterations. From measured results, it was found that the dielectric constant and capacitive value are directed variation with moisture content of soil bricks. Therefore, the moisture content of soil bricks can be found by capacitive measurement. From the measured results, it accurate when comparing the standard measurement with an error of 4–16%.