The free space transmission-reflection method to determine of complex permittivity and complex permeability of the different fillers rubber materials at microwave frequencies / Suhaimi Yahaya

The main objective of this project is to develop a free space measurement system at microwave frequencies in the frequency range of 7.5 to 12 GHz (X-band) for measured a reflection coefficient, Sn and transmission coefficient, S21 of the different filler composition for two major filler which is Carbon Black and China Clay (i.e. 20 part per hundred rubber (pphr) carbon black or 40pphr china clay) for natural rubber. The complex permittivity and complex permeability is calculated from the measured values of Si 1 and S21. Second objective is to proved that increasing a composition of filler will increased the complex permittivity or electrical constant (e*). Third is to proved that rubber is non magnetic material rubber which is gives a complex permeability (u*) equal to 1 for real and 0 for imaginary part. Finally, to prove that the carbon black rubbers have higher conductivity properties compared to the china clay rubbers. The key components of the measurements system consist of transmit and receive spot focusing horn lens antenna, and the vector network analyzer. For thin, flexible samples, the sample had to be sandwiched between two half-wavelength (at mid band) Teflon plate, to eliminate the effect of sagging. Because of the far-field focusing ability of horn lens antennas free-space measurement can be made at microwave frequency in a relatively compact and simple measurement setup.