Abstract：A new free-space measurement for the complex permittivity is proposed.In this method,dielectric periodic structure (DPS) is introduced to the measurement of complex permittivity for the first time.The scattering characteristics of DPS added lossy sample layer are systemically analyzed by a method which combines the multimode network theory with the rigorous mode matching method.The effects of sample complex permittivity on the amplitudes and center frequencies of the maximum reflections are analyzed in details.The method not only overcomes the instability problem and phase-shift ambiguity which exist in the traditional free-space measurement,but also possesses the merit of cavity measurement technique which can accurately determine the complex permittivity of low lossy materials with simple measurement process.The research provides a new method and important theoretical guidelines for the accurate measurement of complex permittivity.
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2013, Vol. 34 
