In particular, Z 0 does not depend any more upon the frequency. The above expression is wholly real, since the imaginary term j has canceled out, implying that Z 0 is purely resistive. For a lossless line terminated in Z 0 , there is no loss of current across the line, and so the voltage remains the same along the line. The lossless line model is a useful approximation for many practical cases, such as low-loss transmission lines and transmission lines with high frequency. For both of these cases, R and G are much smaller than ωL and ωC, respectively, and can thus be ignored.