1) transmission loss by reflection 2) frequency dependency of transmission characteristics 3) standing wave caused by interference between incident and reflected wavesGenerally following parameters are used to evaluate the amount of reflection. We must pay attention that all the parameters other than "reflection coeeficient" have no information about direction of reflection.
The reflection coefficient can be calculated from the "normalized value" of the load impedance.
r = (Zn - 1)/(Zn + 1) Zn = Z/Z0 where r = reflection coefficient Zn = normalized load impedance Z0 = characteristic impedance of line (Ohm) Z = load impedance (Ohm)
Following relations stand for these parameters.
reflection coefficient in power = r^2 VSWR = (1 + abs(r))/(1 - abs(r)) reflection loss = -10*log10(1 - r^2) [dB] return loss = 10*log10(r^2) [dB] r = reflection coefficientThe "abs(x)" replesents absolute value of x. The "log10(x)" replesents the common (base of 10) logarithm of x.