A new free-space method for measurement of electromagnetic parameters of biaxial materials at microwave frequencies

A free‐space method for the measurement of biaxial material is proposed in this paper. Four complex transverse constitutive parameters are directly computed from the reflection and transmission coefficients of a planar sample in free space for the normally incident plane wave with two polarizations. However, because of the extreme insensibility of the reflection and transmission coefficients versus the longitudinal constitutive parameters for thin planar biaxial materials, the correct reconstruction of longitudinal parameters cannot be accomplished by the free‐space method. Considering that the principal coordinate system (PCS) to characterize biaxial material possibly does not coincide with the measurement coordinate system (MCS), an approach to determine PCS is also presented to ensure practicability of this method. A measurement system has been set up to perform measurements of transverse parameters of biaxial material and the validity of this method is experimentally verified. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 72–78, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20905