The reflection coefficient, gamma, defined as Vreflected/Vforward, is obtained as follows:
z0=50.0+0.0j # define system impedance
cv1=1.0+0.0j # V1 as a complex number
cv2=vratio*(cos(phase2advance)+sin(phase2advance)*1.0j) # V2 as a complex number
cvr=2.0*cv1-cv2 # V(R3)
cz=z0*(cv2/cvr) # the same current for both DUT and R3
gamma1=(cz-z0)/(cz+z0) # a well-known formula
swr=(1+abs(gamma))/(1-abs(gamma)) # another well-known formula
# another method
cvfwd=cv1
cvrfl=cv2-cv1
gamma2=cvrfl/cvfwd # check yourself that gamma1 and gamma2 are the same
#
# checking now
#
gamma1=(cz-z0)/(cz+z0) # a well-known formula
=(cz/z0-1)/(cz/z0+1)
=(cv2/cvr-1)/(cv2/cvr+1)
=(cv2-cvr)/(cv2+cvr)
=(cv2-(2.0*cv1-cv2))/(cv2+(2.0*cv1-cv2))
=(2.0*cv2-2.0*cv1)/(2.0*cv1)
=(cv2-cv1)/cv1
=cvrfl/cvfwd
=gamma2
