Propagation and reflection of sinusoidal electromagnetic waves

Beijing Institute of Technology | Ming-Jian Li

The following MATLAB code is a companion code for the course on Artificial Intelligence and Simulation Science. It functions to calculate the propagation and reflection of a sinusoidal electromagnetic wave using the Finite-Difference Time-Domain (FDTD) method.

x
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clear; clc;
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ke = 100;
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% Position of the source
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ks = 1;
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% ks = ke / 2;
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% Number of time steps
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nsteps = 3000;
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% Cell size and time stepping
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c0 = 3.e8;
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dz = 0.01;
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dt = dz / (2 .* c0);
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% Constants
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cc = c0 * dt / dz;
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% Initialize vector
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ex = zeros(1, ke);
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hy = zeros(1, ke);
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space = zeros(1, ke);
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for k = 1:ke
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    space(k) = k*dz;
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end
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empty = zeros(1, ke);
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% sine wave
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amp = 0.5;
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omg = 0.1;
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for t = 1:nsteps
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    % E field loop
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    for k = 2:ke - 1
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        ex(k) = ex(k) + cc * (hy(k - 1) - hy(k));
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    end
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    % Source
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    ex(ks) = amp* sin( omg* t );
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    % H field loop
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    for k = 1:ke - 1
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        hy(k) = hy(k) + cc * (ex(k) - ex(k + 1));
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    end
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    clf
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    plot3(space,ex,empty, 'r', 'LineWidth', 5 ); 
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    axis([0 1 -2 2 -2 2]);
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    set(gcf,'Position',[200 200 1080 720]); 
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    hold on
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    plot3(space,empty,hy, 'b', 'LineWidth', 5 ); 
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    pause(0.001);
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end

The result is as follows.