\begin{table}%t1
\caption{$\eta_{\rm MB}$ and {\it HPBW} along the covered frequency range.\label{tab_eta_hpbw}}
\small%\centering
\par
\begin{tabular}{lll}
\hline 
\hline\noalign{\smallskip}
 Frequency (GHz) & $\eta_{\rm MB}$ & {\it HPBW} ($''$)\\
\hline 
86 & 0.82 & 29.0\\
110 & 0.79 & 22.0\\
145 & 0.74 & 17.0\\
170 & 0.70 & 14.5\\
210 & 0.62 & 12.0\\
235 & 0.57 & 10.5\\
260 & 0.52 & 9.5\\
279 & 0.48 & 9.0\\
\hline
\end{tabular}
\tablefoot{$\eta_{\rm MB}$ and {\it HPBW} along the covered frequency range.}\vspace*{-3mm}
\end{table}