Accurate Permittivity Measurement Considering the Air-gap Effect

A new air-gap correction method for accurately measuring the broadband permittivity of materials based on the transmission/reflection theory is proposed. This method relaxes the fully filled requirement of the specimens and realizes accurate correction for the air-gap effect. A combination strategy of the electromagnetic finite element simulation and the genetic optimization algorithm is employed to extract the true values of the air-gap size and the material permittivity. This is accomplished by minimizing the errors between the measured and the simulated scattering parameters. The high accuracy and practical suitability of the proposed method are validated through experimental tests.