Design of a Microstrip Patch Antenna as a Moisture Sensor

Determining moisture content correctly in different materials or grains is the need of various industries today. Various techniques are suggested in the literature for sensing moisture contents of different materials. Horn antenna and microstrip antenna are the most commonly used antennas for finding moisture content, because of the noncontact type of measurement of moisture present in the sample. The microwave measuring technique offers a very exact and reliable measurement of the concentration of moisture. In the proposed system microstrip patch antenna at 900 MIIz resonant frequency is designed and different materials like sodium carbonate, borax, potassium chloride, and lactose are tested for moisture content. For the fixed quantity of the sample, water content is gradually increased and return loss is measured. It is observed that with the increase in moisture content, return loss decreases.