\begin{table}%t5
\caption{\label{tab5}Specifications of the OMTs.}
\par
%\centering
\par
\begin{tabular}{p{4.5cm}ccc}
\hline\hline\noalign{\smallskip}
 &30 GHz&44 GHz&70 GHz  \\
\hline
Band [GHz] \dotfill &27--33&39.6--48.4&63--77 \\
Isolation [dB] \dotfill &$<$$-40$&$<$$-40$&$<$$-40$ \\
Return loss [dB] \dotfill &$<$$-20$&$<$$-20$&$<$$-20$ \\
Insertion loss at 20~K [dB]  \dotfill &$-$0.15&$-$0.15&$-$0.15 \\
Cross polarisation [dB] \dotfill &$<$$-25$&$<$$-20$&$<$$-20$ \\
\hline
\end{tabular}
\end{table}