fd1d1.m

FDTD simulaton of a pulse hitting a lossy material with epsilonr = 5, sigma=0.05

% Fd1d1.m Dielectric slab (FDTD simulaton of a pulse hitting a lossy material with epsilonr = 5, sigma=0.05)

NN = 200;
kc = NN/2;
k0 = 100;

epsz = 8.85419*10^-12;
ddx = .01;
dt = ddx/(2*3*10^8);

t0 = 50;
spread = 15;

ex = zeros(1,NN);
hy = zeros(1,NN);
ca = zeros(1,NN);
cb = zeros(1,NN);
barr = zeros(1,NN);

% Initialize
for k=1:NN
ca(k) = 1.;
cb(k) = 0.5;
end

epsilon = 5;
sigma = 0.05;
eaf  = dt*sigma/(2*epsz*epsilon);

for k=100:NN
ca(k) = (1 -eaf)/(1+eaf);
cb(k) = .5/(epsilon*(1+eaf));
barr(k) = .5;
end

T = 0;
n_step = 1;
while n_step > 0
n_step = input('How many time steps -->');

for n=1:n_step
T = T + 1;

for k=2:NN-1
ex(k) = ca(k)*ex(k) + cb(k)*( hy(k-1) - hy(k) );
end

pulse = exp(-.5*((t0-T)/spread)^2 );
%pulse = sin(2*pi*T/50);
pulse
ex(2) = pulse;

for k=2:NN-1
hy(k) =  hy(k) + .5*( ex(k) - ex(k+1) );
end

end

subplot(3,1,1)
plot(ex)
hold on
plot(barr,'m--')
hold off
axis( [ 1 NN -.6 1.1 ])
TT = text(  150, .8 , ['T = ',num2str(T)])
set(TT,'fontsize',12)
TT = text(  150, .3 , ['eps = ',num2str(epsilon)])
set(TT,'fontsize',12)
TT = text(  150, -.3 , ['sigma = ',num2str(sigma)])
set(TT,'fontsize',12)
set(gca,'fontsize',12)

saveas(gcf,'pulse.bmp')

end