%  General envelope of standing wave for planewaves 
% normally incident on a planar boundary .  Medium 1 is assumed to be free space
% medium 2 is specified by the user
%       Frank B. Gross
%       Electrical and Computer Engineering
%       2525 Pottsdamer St.
%       Tallahassee, Florida  32310
%       (850) 410-6410
%           Date:  10/08/02


imp=input('Normalized impedance of medium 2=');
G=(imp-1)/(imp+1);
angg=atan2(imag(G),real(G));
bz=-4*pi:.001:0;

figure;
env=sqrt(1+abs(G)^2+2*abs(G)*cos(2*bz+angg));
plot(bz,env,'k')
axis([-4*pi 0 0 1.5])
xlabel('\betaz')
ylabel('|E_1|')
grid on