A study on the coaxial aperture electromagnetic sensor and its application in material characterization

An open-ended coaxial line has been studied by many researchers in order to use it as an electromagnetic sensor for the characterization of materials. These studies include static as well as quasi-static formulations under various simplifying assumptions. In this paper, we use a full-wave formulation of the problem and solve an integral equation to evaluate the aperture field distribution. The electromagnetic field distributions in the material medium as well as the aperture admittance are evaluated subsequently. The effects of a conducting flange over the coaxial opening and the finite sample size are also studied. The results are compared with the experimental data as well as the data obtained by other approaches. An application of this coaxial sensor for the characterization of materials up to 40 GHz is demonstrated.<
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