Skin Depth Calculator on Matlab

skindepth.m

% -------------------------------------------------------------------------
% | Skin Depth Calculator                                                 |
% | =====================                                                 |
% | Olli Vanhoja                                                          |
% |                                                            2010-08-26 |
%                                                                         |
%       e_r1      e_r2                                                    |
%      e_ri1      e_ri2                                                   |
%      mu_r1      mu_r2                                                   |
%                                                                         |
%             |           |                                               |
% E_in -----> | --> x     |                                               |
%        ---  |   |tau|   |                                               |
% gamma     ) |           |                                               |
% P_refl <--  |           |                                               |
%             |           |                                               |
%                                                                         |
% -------------------------------------------------------------------------
clear all
close all
close all hidden
clc

% Parameters
f     = 3*10^9; % Hz
E_in  = 10;     % V/m
e_r1  = 1;
e_ri1 = 0;
mu_r1 = 1;
e_r2  = 15;
e_ri2 = 1.5;
mu_r2 = 1;
sigma = 0;
x     = 0.1;

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

j = sqrt(-1); % Imaginary unit

omega = 2*pi*f;
eps1  = (e_r1-j*e_ri1)*e_0;
eps2  = (e_r2-j*e_ri2)*e_0;

if sigma == 0
    sigma = 1;
end

eta_1 = sqrt((mu_0*mu_r1)/(eps1));
eta_2 = sqrt((mu_0*mu_r2)/(eps2));

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

alpha = sqrt(omega*mu_0*mu_r2*sigma);
E_tau = tau*E_in*exp(-alpha*x);

fprintf('E_in = %f V/m\neta_1 = %f+%fj ohm\neta_2 = %f%+fj ohm\n', E_in, eta_1, imag(eta_1), eta_2, imag(eta_2));
fprintf('gamma = %f\ntau = %f\ngamma+tau = %f\n', gamma, tau, gamma+tau);
fprintf('E_tau = %e V/m\n', E_tau);