Metamaterials最新文献

Volume or statistical averaging of the microscopic Maxwell equations (MEs), i.e. transition from microscopic MEs to their macroscopic counterparts, is one of the main steps in electrodynamics of materials. In spite of the fundamental importance of the averaging procedure, it is quite rarely properly discussed in university courses and respective books; up to now there is no established consensus about how the averaging procedure has to be performed. In this paper we show that there are some basic principles for the averaging procedure (irrespective to what type of material is studied) which have to be satisfied. Any homogenization model has to be consistent with the basic principles. In case of absence of this correlation of a particular model with the basic principles the model could not be accepted as a credible one. Another goal of this paper is to establish the averaging procedure for bulk MM, which is rather close to the case of compound materials but should include magnetic response of the inclusions and their clusters. In the vast majority of cases the consideration of bulk materials means that we consider propagation of an electromagnetic wave far from the interfaces, where the eigenwave in the medium has been already formed and stabilized. In other words, in this paper we consider the possible eigenmodes, which could exist in the equivalent homogenized media, and the necessary math apparatus for an adequate description of these waves. It has to be again clearly emphasized, that the presented paper does not suggest new recipes for the homogenization procedure, but rather summarizes known basics in order to establish solid basis for more particular cases. Nevertheless, it is believed that any homogenization model has to be compatible with the presented in this paper general structure.

A discussion about boundary conditions and layered MM is a subject of separate publication and will be done elsewhere.

A comment on the Review by A. Chipouline, C. Simovski and S. Tretyakov, Metamaterials 6 (2012) 77–120.

In this paper the metamaterial properties of two-dimensional arrays of circular antidots (holes) embedded into a ferromagnetic medium of Permalloy are studied according to both micromagnetic and analytical calculations. The periodicity of the arrays and the diameters of the antidots are in the nanometric range. The collective mode dynamics is described by means of effective physical quantities for the scattering geometry with the external magnetic field applied perpendicularly to the Bloch wave vector in the antidot plane. As an example, the definition of an effective field, incorporating the demagnetizing effects due to the holes, permits to describe the dynamical properties of collective modes in terms of effective properties in the travelling regime. An effective wavelength and a small wave vector are introduced both for extended and localized magnonic modes. By means of these effective quantities it is shown that holes play the role of point defects affecting the spin dynamics in the microwave range. Relations between the effective wavelength and the Bloch wavelength and between the corresponding small wave vector and the Bloch wave vector are found. Some effective rules on the dynamic magnetization, based upon the effective wavelength and the corresponding small wave vector, are derived. An application that exploits the definition of the small wave vector is proposed and an experiment based upon the notion of effective wavelength and small wave vector is suggested.

In this paper a compact one unit cell mu negative (MNG) zeroth-order resonator (ZOR) antenna is designed and analyzed. A ZOR antenna based on the MNG transmission line (TL) has been previously introduced. The feeding structure of the previously presented MNG antenna is a microstrip line in parallel with the antenna. This feeding mechanism enlarges the overall size of the antenna and also increases the cross polarization level of the radiated fields. In this paper we propose a MNG TL based ZOR antenna with a coaxial feed and with a specific matching mechanism which results in compactness of the antenna and reducing its cross polarization level. An approximate design method for the proposed antenna is presented using its equivalent circuit and according to its operation mechanism. A prototype antenna has been fabricated and tested. The measured return loss and radiation patterns are given and the overall performance of the antenna is compared with some of the previously reported compact metamaterial antennas.