Simulation method of ultra wideband electromagnetic wave

Abstract

The invention discloses a simulation method of ultra wideband electromagnetic waves. The invention proposes a new PML method on the basis of the PML method under a stretch coordinate system and a difference scheme of a higher-order time domain finite difference method (FDTD (2, 2M)). A piecewise linearity convolutional perfectly matched layer (PCPML, Piecewise linearity CPML) under self-adapting absorption parameters absorbs a boundary condition. PML absorption factors are set to be adjustable parameters by the method so as to absorb different ultra wideband electromagnetic waves from high frequency to low frequency, and the parameters are obtained by a mixed method of an optimization method of a real coding genetic algorithm and a linear iteration method in a self-adapting manner so as to adapt to the absorption of ultra wideband electromagnetic waves. The absorption boundary condition adopted by the method can absorb and process high frequency waves and low frequency waves, and also can reduce the reflection error of a matched layer caused by grid dispersion and edge reflection and improve the absorption efficiency and the accuracy of simulation result.

Description

technical field [0001] The invention belongs to the category of ultra-broadband electromagnetic wave three-dimensional numerical simulation technology, and is a three-dimensional electromagnetic prospecting forward modeling method for simulating the propagation of ultra-broadband electromagnetic waves in complex lossy media containing both air and underground. Background technique [0002] Using ultra-wideband electromagnetic waves to detect underground targets or detect life through walls is a cutting-edge technology that can be used in geophysics, ultra-wideband antenna design, radar target detection, and search for life through walls. At present, when simulating the propagation of ultra-broadband electromagnetic waves in complex media, there are generally problems such as difficult processing of truncated boundaries and poor accuracy of long-term reflection signals. [0003] The ultra-broadband electromagnetic pulse is a transient electromagnetic wave, and the simulation ...

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Problems solved by technology

However, for ground exploration, the calculation space is large, the geoelectric distribution of the medium model is extremely complex, the reflection delay time is long, and the accuracy of the late echo signal is high. At this time, the general absorption boundary processing method such as Mur( G.Mur, 1981) absorbing boundary method, superabsorbing boundary method, general PML (Perfectly Matched Layer, 1994) method, etc. cannot deal with the absorption of ultra-broadband electromagnetic waves in complex media

The frequency band of ultra-broadband electromagnetic waves propagating in complex media is very wide, and evanescent waves, high- and low-frequency waves are very rich, especially low-frequency electromagnetic waves, which are difficult to be absorbed by general absorption methods, and long-term reflected waves are affected by grid dispersion and boundary reflection. , especially the influence of boundary reflection is extremely large, resulting in very low simulation accuracy; in addition, the traditional PML absorption boundary processing method needs to artificially set absorption parameters such as the number of layers of the absorption medium, directional conductivity, etc., for any complex lossy model, It is difficult to artificially set the absorption parameters that can reasonably simulate ultra-broadband electromagnetic waves. People hope that the computer can automatically give the optimized absorption parameters according to the given geoelectric model to obtain accurate simulation results.

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