Miniaturized coaxial cavity resonator based on anisotropic negative permeability metamaterial loading

In this letter, a miniaturized coaxial cylindrical cavity resonator was presented, in which a combination of an ordinary dielectric material and a metamaterial layer has been inserted. First, the general dispersion relation was formulated for such a resonator in three different cases in which the metamaterial layer is: (i) an isotropic μ and ε negative (double negative or DNG) medium; (ii) an isotropic μ negative (MNG) medium; or (iii) an anisotropic MNG (AMNG) medium. Extracting the approximate dispersion relation in the subwavelength scenario, it is shown that this configuration may in principal exhibit an arbitrary low resonant frequency for a fixed dimension, not only in the case of isotropic DNG or isotropic MNG layers but also in the case of a much less complex AMNG layer, which is of importance from the practical realization point of view. In comparison with miniaturized rectangular cavities and also miniaturized one‐dimensional resonators, the aforementioned resonator provides the possibility of selecting a distinct mode and also provides a further degree of freedom in the approximate dispersion relation, which brings more flexibility in designing miniaturized resonators. As an example, design and simulation of a miniaturized coaxial cavity resonator together with the complete design of the AMNG layer are presented. The resultant cavity diameter is shortened by ∼ 60% in comparison with theoretical minimum dimensions of a cylindrical cavity resonator of the same height. Finally, the designed cavity has been fabricated and tested. The measured and simulated responses are in close agreement with each other. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:595–599, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26600