We consider z=-l as the point which is the entry of the transmission line. Now, by the general equation the impedance in transmission line, we are going to get a particular solution for Zin. Applying general equation, Recall Notice That Then we have
Notice That : (1) VSWR =1 means no reflection (2) VSWR =infinity means wave is totally reflected
That implies that if one of the points in the figure |V|/|V|(max) touches zero, VSWR -> infinity
In other words, when VSWR= infinity, there exists some/a point(s) such that the wave is total cancelled due to suposition between incident wave and reflected wave.
Important Notes: (1)Once again VSWR is a ratio comparing between Max and Min e.g VSWR= n means VSWR= n:1 etc. (2)The particular representation for |V|/|V|(max), you may consider Then, by the consideration of different z, you can get the values of each point one by one and at the end obtain the figure.
Due to the phase difference in the transmittion line, the same wave in the same direction in different point may have different magnitude, given by a phasor: The former expotental function represents the drop of amplitude,where the latter one indicates the phase angle of a particular wave.