clear
Z0=75;
ZL=37.5+1i*75; % 迹
Gamma0=(ZL-Z0)/(ZL+Z0)
SWR = (1+abs(Gamma0))/(1-abs(Gamma0))

f=3*10^9;
c=3*10^8;
lambda=c/(f*(2.56)^(1/2));
l=0.02;
Gammain=Gamma0*exp(-2*1i*2*pi/lambda*l)
Zin=Z0*(ZL+1i*Z0*tan(2*pi/lambda*l))/...
    (Z0+1i*ZL*tan(2*pi/lambda*l))
Gammain=(Zin-Z0)/(Zin+Z0)