Complex Permittivity and Permeability Measurement Method of Multiple Free-Space Incident for Structured Absorbing Materials

In this paper, a novel technique is presented for measuring permittivity and permeability of honeycomb structured absorbing materials by multiple incident free-space method. The measurement system consists of transmit and receive horn antennas mounted on an arch frame, a network analyser and a flat test bench. The reflection coefficients S
₂₁
of metal-backed specimen is obtained with different incident angle. The complex permittivity and permeability can be extracted from three S
₂₁
by genetic algorithm. Very good agreement is observed between simulated and measured S-parameter of honeycomb structured absorbing materials. The convenience of this approach is the simple calibration procedure besides free-space measurement advantage.