Question 9.9: A lossless transmission line of Ro = 75[Ω] has a length of l......

(a) Shorted terminal has Z_{L} = 0                         : z_{L} = r + jx = 0 + j0 .
The r = 0 circle and the x = 0 circle intersect at point V (see Fig. 9.16)
Point V gives |Γ| = 1 and Φ = π.     : Γ = −1.
The line length \ell  = λ /8 corresponds to a wtg of 0.125λ.

Move from point V to point W by increasing the wtg by 0.125λ .
Point W gives r = 0 and x = 1 : Z_{in} = j  75 [Ω].

(b) Open terminal has Z_{L} = \infty                        : z_{L} = r + jx = \infty + j\infty .
The r = ∞ circle and the x = ∞ circle intersect at point X (see Fig. 9.16).
Point X gives |Γ| = 1 and Φ = 0                          : Γ = 1.
Move from point X to point Y by increasing the wtg by 0.125λ .
Point Y gives r = 0 and x = −1                    : Z_{in} = – j 75 [\Omega] .