Characteristic Modes Analysis of Resonant and Non Resonant Planar Structures on Magneto-Dielectric Substrates

This article presents the analysis of microstrip structures on magneto-dielectric substrates and their mutual coupling. Characteristic modes theory is used to evaluate the net modal energy stored in the near-field of the structure. It is shown that microstrip structures printed on magneto-dielectric substrate have a lower net modal stored energy than those printed on purely dielectric substrates. The coupling between microstrip resonator is analyzed using the theory of inter-modal coupling and has a slightly lower value on magneto-dielectric substrate than purely dielectric ones, with the same level of miniaturization. Hence, magneto-dielectric substrate is then a better alternative to design miniature microstrip structures with a level of mutual coupling lower than their equivalent highly-dielectric materials.