Maximum VSWR that can be tolerated?
Ifor and Iref constructively interferring
\begin{equation}
I_{max} = I_{for}+I_{ref} = 20a
\end{equation}
Power delivered to the load
\begin{equation}
P_{for}-P_{ref}=50I_{for}^2-50I_{ref}^2=10000w
\end{equation}
Two Equations and two unknowns, solve for Ifor and Iref interferring destructively = Imin
\begin{equation}
I_{for}=15a, I_{ref}=5a, I_{min}=I_{for}-I_{ref}=10a
\end{equation}
Calculate Imax/Imin
\begin{equation}
SWR_{max}=I_{max}/I_{min}=20/10=2:1
\end{equation}