Free space measurement of complex permittivity and complex permeability of ferrites materials using transmission reflection method at microwave frequencies / Hasbullah Hassan

Measurement of complex permittivity (ε*) and complex permeability (µ*) at frequency range 7.5 to 12.5 GHz using transmission reflection method are presented for ferrites material. In this method, the complex permittivity and complex permeability will be calculated from the measured value of reflection coefficient (S11) and transmission coefficient (S21). The key components of measurement systems are a pair of spot-focusing horn lens antennas, vector network analyzer and the computer. Because of the far field focusing ability of horn lens antennas, the free space measurement can be made at microwave frequency in a relatively compact and simple measurement set up. The free space line reflects line (LRL) calibration technique is using to eliminate the errors due to multiple reflections between antennas via the surface of the sample. For ferrite that is have high complex permittivity, the sample need to be sandwiched between two quarter wavelength (at mid-band) teflon plates, to eliminate the effect of non-matching problem.