Time domain analysis method of thin-layer electromagnetic structure based on surface impedance boundary

Abstract

The invention discloses a time domain analysis method of a thin-layer electromagnetic structure based on a surface impedance boundary. The method comprises the following steps: establishing an equivalent transmission line circuit model of a thin-layer artificial electromagnetic structure unit by applying an equivalent transmission line circuit theory; extracting equivalent surface impedance of thethin-layer artificial electromagnetic structure unit, and fitting the equivalent surface impedance of the broadband into a rational fraction accumulation form by adopting a vector fitting method; carrying out full-wave simulation on the structure by using a time domain finite difference method based on a surface impedance boundary condition, wherein the surface impedance boundary condition is used for replacing a thin-layer artificial electromagnetic structure unit in the simulation process; and carrying out post-processing on the electromagnetic field obtained by the full-wave simulation. According to the method, for calculating the thin-layer artificial electromagnetic structure, the longitudinal and transverse calculation unknown quantities of the thin-layer structure are remarkably reduced, the operation time and memory are saved, and high flexibility and effectiveness are achieved.

Description

technical field [0001] The invention belongs to the numerical calculation technology of target electromagnetic reflection and transmission characteristics, in particular to a time-domain analysis method of a thin-layer electromagnetic structure based on surface impedance boundaries. Background technique [0002] Since the new concept of thin-layer artificial electromagnetic structure was proposed, the FDTD method has been used by many domestic and foreign scientists to analyze its electromagnetic properties. The finite-difference time-domain algorithm is a time-domain method that directly solves Maxwell’s differential equations. During the iterative solution process, the electromagnetic field value of a certain node in space is associated with the electromagnetic field values ​​​​of four adjacent nodes around it. And spatial "leapfrog" iterations, and then solve the electromagnetic field in a certain time domain. The FDTD method uses a hexahedral grid to subdivide the calcu...

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Problems solved by technology

However, when sub-wavelength structures such as thin-layer artificial electromagnetic structures are introduced into the calculation domain, it is necessary to use fine grids to subdivide the thin-layer artificial electromagnetic structures, which will consume a lot of computer memory and simulation calculation time.

[0003] Using existing techniques, such as the traditional FDTD-IBC method (V.Nayyeri, M.Soleimani, O.M.Ramahi, "Modeling graphene in the finite-difference time-domain method using a surface boundary condition," IEEE Trans. Antennas Propag., vol.61, no.8, pp.4176-4182, May 2013) can reduce the unknown quantity and realize the improvement of calculation efficiency, but only reduce the unknown quantity in the vertical direction, and the unknown quantity in the horizontal direction is not reduced; the traditional GSTC Methods (C.L. Holloway, E.F. Kuester, J.A. Gordon, J.O'Hara, J. Booth, and D.R. Smith, "An overview of the theory and applications of metasurfaces: the two-dimensional equivalents of metamaterials," IEEE Antennas Propag. Mag., vol. 54, no.2, pp.10-35, Feb.2012; K.Achouri, M.A.Salem, and C.Caloz, "General metasurface synthesis based onsusceptibility tensors," IEEE Trans.Antennas Propag., vol.63, no. 7, pp. 2977-2991, Jul.2015) can only accurately calculate the case of thin-layer without substrate, and lacks efficient electromagnetic simulation methods to analyze thin-layer artificial electromagnetic structures

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