Contents
Section 1. Topics on theoretical electrodynamics
High frequency permeability of the system of hollow ferromagnetic particles
A.O. Sboychakov
Abstract
The paper studies high-frequency permeability of the composite materials consisting of hollow ferromagnetic particles embedded into the non-magnetic media. It is assumed that the ferromagnetic particles have spherical shape, and the thickness of the ferromagnetic region d is much smaller than the particles’ diameters D. It was shown recently [Modern Electrodynamics, 5 (7), p. 15 (2023)], that under certain conditions, the magnetization distribution in such a particles is non-uniform, but form a vortex-like structure: the magnetization is twisted in some plain outside two domains placed at the poles of the particle. The high-frequency permeability of such a composite material has been studied at d/D << 1 and in the limit of non-interacting particles. It was shown, in particular, that the frequency dependence of the particle’s susceptibility is quite similar to that for the thin film. At the same time, the magnetization oscillations in the ac field are non-homogeneous.
Keywords: magnetic composites, magnetic permeability
Section 2. Topics on interaction of an electromagnetic field with materials
Modeling and comparative analysis of structures that improve antenna isolation in MIMO technology antenna arrays
V.E. Kutepov, I.V. Peshkov
Abstract
This article provides a comprehensive analysis of the reduction of the mutual coupling between the radiating elements of MIMO antenna arrays when using semiconductor structures with an electromagnetic band gap in the form of a combination of a single-plane swastika-combed and spiral-meander, as well as a separate mushroom-shaped cross and a deformed earth structure with L-shaped plugs. Models of all three antenna arrays have been developed, the transmission characteristics of the resulting models have been calculated and analyzed, a comparative analysis has been carried out to determine the effectiveness of the antenna systems under consideration, to identify their advantages and disadvantages, to determine the most optimal use and practical application in local wireless networks, as well as the features and conditions within the framework of the introduction of MIMO antenna arrays. Using the developed models, the power transmission coefficients, gain coefficients (DG) AP, correlation coefficients of antenna array envelopes (ECC), antenna efficiency coefficients (MEG), total active reflection coefficient (TARC) for each structure of reducing mutual coupling, as well as channel bandwidth loss (CCL) were studied. Based on the results of preliminary calculations, modeling and processing of the results, it is demonstrated that it is possible to significantly reduce the interconnection of antenna array elements, taking into account the individual characteristics of each structure under consideration.
Keywords: MIMO, DGS, EBG, inductance, capacitance, ECC, MAG, TAC, CCL
Section 3. Metodological notes
Stimulated Raman Scattering and Raman Laser Operation
E.S. Andrianov, A.P. Vinogradov, A.A. Pukhov
Abstract
The nature of Raman laser pumping is not related to the excitation of any levels of the electron subsystem of Raman-active molecules filling the laser resonator. In fact, amplification occurs due to the nonlinear interaction of Raman-active molecules with two coherent electromagnetic wave fields, the pump wave field and the resonator mode field. Such a pumping mechanism does not require the creation of an inverse population of any levels of the molecule. The operation of a Raman laser can be described classically within the framework of nonlinear optics as a generator with coherent pumping. The conditions for the emergence of a coherent component at the resonator frequency, necessary for turning on the Raman amplification mechanism, are discussed.
Keywords: Raman scattering, Purcell effect, spontaneous and stimulated emission, virtual levels
Editorial address: 13 b. 6, Izhorskaya st.,
This site respects your rights and maintains confidentiality when filling out, transmitting and storing your confidential information.
Placing an application on this site means your consent to the processing of data and the further transfer of your contact information to our company.
Personal data means information related to the subject of personal data, in particular the name, contact details (email address) and other data classified as personal data by Federal Law of July 27, 2006 No. 152-FZ “On Personal Data.”
The purpose of processing personal data is to inform about the services provided by our company.