An Improved Two-Layer Method for Nondestructively Characterizing Magnetic Sheet Materials Using A Single Rectangular Waveguide Probe

An improved single waveguide probe technique is presented to nondestructively determine the permittivity and permeability of sheet materials. The impetus for the technique is to address the unreliable results yielded by the existing single probe two-layer method while preserving its physical ease of measurement. Included in this article is the theoretical development of the method and its experimental validation. The theoretical development uses Love's equivalence theorem to derive a magnetic field integral equation that is subsequently solved for the theoretical reflection coefficient using the method of moments. Experimental permittivity and permeability results for two magnetic shielding materials are presented and compared to results obtained using established techniques to validate the proposed method. Profile plots of the electric and magnetic fields in the material under test region of the measurement geometry are provided and analyzed to yield further physical insight.