Transmission Coefficient Calculator on Matlab

transcoeff.m

% -------------------------------------------------------------------------
% | Transmission Coefficient Calculator                                   |
% | ===================================                                   |
% | Olli Vanhoja                                                          |
% |                                                            2010-08-26 |
%                                                                         |
%       e_r1     e_r2                                                     |
%      mu_r1     mu_r2                                                    |
%                                                                         |
% P_in        |     tau                                                   |
% E_in -----> | --> P_tau                                                 |
%        ---  |                                                           |
% gamma     ) |                                                           |
% P_refl <--  |                                                           |
%             |                                                           |
%                                                                         |
% -------------------------------------------------------------------------
clear all
close all
close all hidden
clc

% Parameters
P_in  = 1*10^-3;
e_r1  = 2.1;
mu_r1 = 1;
e_r2  = 1;
mu_r2 = 1;

% Constants
c_0  = 299792458;
mu_0 = 4*pi*10^-7;
e_0  = 1/(mu_0*c_0^2);

eta_1 = sqrt((mu_0*mu_r1)/(e_0*e_r1));
eta_2 = sqrt((mu_0*mu_r2)/(e_0*e_r2));

gamma = (eta_1-eta_2)/(eta_1+eta_2);      % Reflection coefficient
%tau   = (2*eta_2)/(eta_2+eta_1);          % Transmission coefficient
tau   = 1-abs(gamma);

P_refl = (gamma^2*eta_2)/(eta_1)*P_in;
P_tau  = (tau^2*eta_1)/(eta_2)*P_in;

fprintf('P_in = %f W\neta_1 = %f ohm\neta_2 = %f ohm\n', P_in, eta_1, eta_2);
fprintf('gamma = %f\ntau = %f\ngamma+tau = %f\n', gamma, tau, abs(gamma)+tau);
fprintf('P_refl = %f\nP_tau = %f\n', P_refl, P_tau);