Determination of Moisture Content of Hevea Rubber Latex Using a Microstrip Patch Antenna

A microstrip patch sensor for determination of moisture content in Hevea Rub- ber Latex is presented in this paper. The microstrip patch sensor was designed to operate at microwave frequency range from 0.1 to 5GHz on a RT/Duroid substrate with 6:15 § 0:015 per- mittivity and 1.27mm thickness. The width and length of the rectangular patch antenna was 18mm and 38mm, respectively. The re∞ection coe-cient of the sensor loaded with Hevea latex at various percentages of moisture content from approximately 42.47% (fresh latex) to 77.57%. Calibration equations have been established between moisture content and magnitude of re∞ec- tion coe-cient at several selected frequencies. These equations were used to predict the amount of moisture content on Hevea latex based on the measured re∞ection coe-cient values. The ac- tual values of moisture content were obtained using standard oven drying method. The lowest mean relative error between actual and predicted moisture contents was 0.06 at 3GHz.