Simultaneous Evaluation of Permeability and Permittivity Using a Flexible Microstrip Line-Type Probe up to 67 GHz

Complex relative permeability and permittivity were evaluated simultaneously in the band of 100 MHz–67 GHz using a flexible microstrip line-type probe. In principle, the probe can evaluate the permeability and permittivity of electromagnetic materials regardless of size. The measured permeability and permittivity were obtained from the transmission coefficient (
$S_{21}$
). Since
$S_{21}$
under the infinite magnetic field can be estimated by changing the dc magnetic field stepwise, the magnetic and dielectric signals were separated accurately. The complex permeability and permittivity of a NiZn ferrite sheet (10 mm
$\times10$
mm, 0.1 mm thick) and polytetrafluoroethylene (PTFE) (25 mm
$\times25$
mm, 0.79 mm thick) were evaluated accurately.