Free space measurement technique on dielectric properties of agricultural residues at microwave frequencies

Principles to determine dielectric properties measurement using microwave free-space transmission measurements technique is presented in this paper. The project´s main objective was to measure the dielectric properties of different agricultural waste material at microwave frequencies, which in turn, can serve as a potential alternative, replacing conventional printed circuit board (PCB) using FR4 material. A system, which includes a PNA vector network analyzer, horn antennas, and Agilent Technologies 85071E material measurement software were used and described in detail. Techniques and procedures essential in obtaining reliable permittivity data for agricultural waste products were also discussed. The waste products - rice husk, rice straw, and kenaf were studied in the frequency range of 2.2 to 3.3 GHz. These agricultural waste materials were mixed with two distinct resins, namely, Urea Formaldehyde (UF) and Phenol Formaldehyde (PF). Each type of resin was also investigated using different percentage of resin moisture content, and the results were analyzed thoroughly.