\documentclass{standalone}

\usepackage{tikz}
\usepackage{circuitikz}
\begin{document}
	\tikzstyle{block} = [draw, fill=white, rectangle, 
	minimum height=3em, minimum width=3em]
	\begin{circuitikz}
		\draw (0,4) to [twoport,t=$Z_g$](4,4);
		\draw (4,0) to[TL] (10,0);
		\draw (4,4) to[TL]  (10,4);
		\draw (10,4) to [twoport,t=$Z_L$](10,0);
		\draw (0,0) to [sI] (0,4);
		\draw (4,0) to (0,0);
	\end{circuitikz}
\end{document}