A Novel Technique for Measuring One-Dimensional Permittivity Profiles Using a Simple Non-Commensurate Planar Structure

A novel technique is presented for measuring one-dimensional permittivity profiles based on a simple planar structure. The measuring device consists of a transmission line loaded with open-ended stubs of non-commensurate lengths. The permittivity profile of the material under test is evaluated by simply measuring the attenuation pole frequencies in the transmitted RF signal due to the different loaded stubs. The proposed technique provides reliable results for both continuous and discontinuous permittivity profiles without requiring any a priori information of the unknown profile. Measurements using different materials have been performed resulting in good agreement with data from the literature.