Anisotropic Permittivity Measurement Using Lens Antennas

A free-space measurement system based on lens antennas for measuring the complex permittivity of anisotropic materials in the band from 8.5 to 12.4 GHz is proposed. The multireflect-thru method is used to calibrate the measurement system in the whole band. Only the transmission coefficient (S21) is used to solve the permittivity. The validity and accuracy of the system for measuring permittivity are verified by the measurement results of polytetrafluoroethylene (PTFE).