\begin{table}%t1
\caption{\label{tab1}Summary of the adopted notation.}
%\centerline
 { \small \begin{tabular}{lccc}
\hline\hline
 & $A$ & $p$ & $P$ \\
 \hline\noalign{\smallskip}
Incoming radiation $\widetilde E ^a$ & $E_{\rm R}, E_{\rm L} $ & $\delta_{\rm R},\delta_{\rm L} $ & $\Delta=\delta_{\rm R}-\delta_{\rm L}$ \\
Cross term $\widetilde D $ & $D_{\rm R} ,D_{\rm L} $ & $\varphi_{\rm R},\varphi_{\rm L}$ & $\Phi=\varphi_{\rm L}-\varphi_{\rm R}$ \\
Receiver gain $\widetilde{G}$ & $G_{\rm R},G_{\rm L}$ & $\psi_{\rm R},\psi_{\rm L}$ & $\Psi=\psi_{\rm L}-\psi_{\rm R}$ \\
Total Power gain $g$ & $g_1,g_2$ & $-$ & $-$ \\
Polarimeter gain $\widetilde g$ & $g_Q,g_U$ & $\gamma_Q,\gamma_U$ & $-$ \\
Outgoing signal $\widetilde V$ & $V_{\rm R},V_{\rm L}$ & $-$ & $-$ \\
\hline
\end{tabular}}
\medskip
$^a$ All complex quantities are expressed in the form $\widetilde{A}=A{\rm e}^{{\rm i}p}$, where $A$ is the amplitude and $p$ is the phase. $P$ is the phase difference between the two channels.
\end{table}