Different types of reflection/TDR casic
Q: What do they mean?


Those graphs are voltages at source terminal vs time.

The x-axis has two inflections, t=0 and t when wave reach the source again. The input is always Ei and the second value you see is the voltage at input terminal after reflecting.



Q: How to get these?


Deriving Zl=f(Eo,Ei)*Zo using reflection coefficient formula, 

$$Γ=\frac{\ Z_L-Z_o}{\ Z_L+Z_o}$$

rearranging

$$Z_L=\frac{-(Γ+1)Z_o}{(Γ-1)}$$

and using

$$Γ=\frac{E_o}{E_i}$$

we have


  $$Z_L=\frac{E_o+E_i}{E_i-E_o}Z_o$$




You can use this formula by substituting Ei=1 and Eo=-1/3 , 1/3, 0, 1.
For example Eo=-1/3,
$$Z_L=\frac{1}{2}Z_o$$