Determination of Pulverized Material Permittivity for Microwave Absorber Application

This paper presents the material characterization of agricultural waste by determining its dielectric properties for microwave absorber application. Three proposed materials, which are empty fruit bunch, oil palm frond and rice husk were investigated for the frequency ranging from 10 GHz to 20 GHz. The methodology was developed using the combination of three techniques involving coaxial probe technique, material density measurement and dielectric mixture model. It is found that the material density and air-particle permittivity have the impact on the wave absorption of the material. The result shows that all three agricultural wastes are capable to absorb electromagnetic signal. The average dielectric constant for solid pulverized agricultural waste are 3.49, 4.06 and 3.31 for empty fruit bunch, oil palm frond and rice husk respectively. Furthermore, at of 15.0 GHz, the solid pulverized empty fruit bunch, oil palm frond and rice husk indicate the highest loss tangent with value of 0.2201, 0.2579 and 0.2218 respectively which contributed from the loss factor of the material complex permittivity.