clear
  clc
  close all
  
  L = 10e-2
  c = 299792458
  R = 0.99991
  
  fsr = c/(2*L)
  
  fc = fsr*128760;
  df=20e6;
  
  f = 2*pi*linspace(fc-df, fc+df, 10000);
  
  fpt = ((1.-R).*exp(-2.*L.*i.*f./c))./(1.-R.*exp(-2.*L.*i.*f./c));
  fpr = sqrt(R).*(1.-exp(-2.*L.*i.*f./c))./(1.-R.*exp(-2.*L.*i.*f./c));
  
  figure
  plot(f,abs(fpr))
  
  
  fm = 23e6;
  
  fm1 = sqrt(R).*(1.-exp(-2.*L.*i.*(f.+fm)./c))./(1.-R.*exp(-2.*L.*i.*(f.+fm)./c));
  fm2 = sqrt(R).*(1.-exp(-2.*L.*i.*(f.-fm)./c))./(1.-R.*exp(-2.*L.*i.*(f.-fm)./c));
  
  ff=fpr.*conj(fm1)-conj(fpr).*fm2;
  iff = imag(ff);
  
  figure
  plot(f,iff)