tmm

% Transfer matrix method
% Author: Shuakat
% ITMO University.


close all;
clear all;
N = 1e3;
lam = linspace(50,100,N);
k = (2*pi)./lam;

er_layer = [2 3];
ur_layer = [1 1];
len_layer = [0.5 0.5].*sqrt(3);

k_layer = k.*sqrt(er_layer(1)*ur_layer(1));

incW = zeros(1,N);
refW = zeros(1,N);
incW_tmp = zeros(1,2);
refW_tmp = zeros(1,2);
incW(1) = 0.8;
refW(1) = 1-0.64;

r = zeros(1,N);
t = zeros(1,N);

for i=1:length(lam)-1
    incW_tmp(1) = incW(i);
    refW_tmp(1) = refW(i);
    for j=1:length(len_layer)-1
        M11 = cos(k_layer(i)*len_layer(j));
        M12 = sin(k_layer(i)*len_layer(j))/k_layer(i);
        M21 = -k_layer(i)*sin(k_layer(i)*len_layer(j));
        M22 = cos(k_layer(i)*len_layer(j));
        S11 = M12/M22;
        S12 = (M11*M22-M12*M21)/M22;
        S21 = 1/M22;
        S22 = -M21/M22;
        incW_tmp(j+1) = incW_tmp(j)*S11 + refW_tmp(j)*S12;
        refW_tmp(j+1) = incW_tmp(j)*S21 + refW_tmp(j)*S22;
    end
    incW(i+1) = incW_tmp(end)*M11 + refW_tmp(end)*M12;
    refW(i+1) = incW_tmp(end)*M21 + refW_tmp(end)*M22;
    r(i) = incW(i+1)/incW(i);
    t(i) = incW(i+1)/refW(i);
end;
figure
plot(lam,r./max(abs(r)),lam,t./max(abs(t)));
% plot(lam,incW./max(abs(incW)),lam,refW./max(abs(refW)));