Design and Development of Slot-Loaded Microstrip Patch Antenna for Moisture Sensor Applications

This paper explores the feasibility of using microstrip patch antennas as sensors by analyzing the correlation between dielectric constant variations and resonant frequency shifts. A Microstrip patch antenna is designed at 2.4 GHz and a slot introduced in the substrate to accommodate different materials. Microstrip Patch Antenna with slot is fabricated and transmission line parameters are measured. Without any test material Return loss, VSWR and impedance are measured as <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$-15 ~\text{dB}, 1.43$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$44.3-\mathrm{j} 15$</tex> ohm respectively for the antenna. Test materials such as A2, A3, A4 Paper are inserted into the substrate and return loss, VSWR, Impedance are measured. From these results, the changes in the resonant frequency, return loss and VSWR are determined. This slot loaded antenna can find application as moisture sensor for certain materials.