Showing papers on "Cylindrical harmonics published in 2020"
TL;DR: In this article, the exact formulas for the induced electric surface current (in the scattering phenomenon) and the equivalent electric surface currents in the diffraction phenomenon on the open cylindrical surface due to an arbitrary narrow-band beam have been shown in their closed-form expressions within the context of the cylinear harmonics, which gives information about the validity of the Physical Optics (PO) approximation.
Abstract: The exact formulas for the induced electric surface current (in the scattering phenomenon) and the equivalent electric surface current (in the diffraction phenomenon) on the open cylindrical surface due to an arbitrary narrow-band beam have been shown in their closed-form expressions within the context of the cylindrical harmonics, which gives information about the validity of the Physical Optics (PO) approximation. Both the Electric Field Integral Equation (EFIE) and the Magnetic Field Integral Equation (MFIE) are used to find the induced (equivalent) electric surface currents in the context of the cylindrical harmonics. The numerical example of the scattering and diffraction of the Hermite Gaussian beam from the open cylindrical surface is shown. The result is useful for the evaluation of the validity of the PO approximation in the cylinder-like surface.
10 citations
TL;DR: The cylindrical Taylor Interpolation through FFT (TI-FFT) algorithm for computation of the near-field and far-field in the quasi-cylindrical geometry has been introduced and has the advantages of small sampling rate (large sampling spacing) and no singularity problem.
Abstract: The cylindrical Taylor Interpolation through FFT (TI-FFT) algorithm for computation of the near-field and far-field in the quasi-cylindrical geometry has been introduced. The modal expansion coefficient of the vector potentials ${\bf F}$ and ${\bf A}$ within the context of the cylindrical harmonics (TE and TM modes) can be expressed in the closed-form expression through the cylindrical addition theorem. For the quasi-cylindrical geometry, the modal expansion coefficient can be evaluated through FFT with the help of the Taylor Interpolation (TI) technique. The near-field on any arbitrary cylindrical surface can be obtained through the Inverse Fourier Transform (IFT). The far-field can be obtained through the Near-Field Far-Field (NF-FF) transform. The cylindrical TI-FFT algorithm has the advantages of $\mathcal{O} \left( \hbox{N} \log_2 \hbox{N} \right)$ computational complexity for $\hbox{N} = \hbox{N}_\phi \times \hbox{N}_z$ computational grid, small sampling rate (large sampling spacing) and no singularity problem.
10 citations
TL;DR: In this article, an analytical model of the magnetically active part of a linear electric generator was proposed based on the assumption of the periodicity of linear translational motion of the armature relative to the stationary cylindrical winding.
Abstract: Linear electric generators are increasingly used in autonomous systems that require a compact source of electricity and when it is necessary to simplify mechanisms of power systems. To study the characteristics of a linear electric generator, an analytical model of its magnetically active part was proposed. The model is based on the assumption of the periodicity of linear translational motion of the armature relative to the stationary cylindrical winding. Based on the representation of the magnetic field of the generator’s armature by cylindrical harmonics of the scalar potential, the magnetic flux generated by the inductor was analyzed. The inductor design contains several pairwise oppositely oriented cylindrical permanent magnets. The use of representations based on cylindrical harmonics for the magnetic flux and EMF induced in a circular circuit has made it possible to substantiate the rational number of cylindrical armature magnets and their geometric parameters. The losses caused by the technological necessity of using annular magnets instead of solid continuous cylindrical ones with the same overall dimensions were estimated. Analysis of losses of the magnetic flux linkage with the current winding resulting from the presence of technologically necessary clearance between the permanent magnets and the winding sections was carried out. An analysis of arrangement and switching of the winding sections was carried out. It has made it possible to justify the choice of rational cross-sectional dimensions. For experimental verification of the analytically obtained results, a physical model of a linear electric generator with an armature containing permanent cylindrical magnets was designed. Its translational periodic movement was provided through an external electric drive. Analysis of the EMF dependences recorded with a digital oscilloscope with a small (5 %) error has confirmed the obtained analytical results and correctness of the theses underlying the model