## 4 Conclusions  
This article introduces a dual-band frequency selective surface that displays different polarization selectivity in two passbands. The two passbands utilize orthogonally polarized incident waves and each band edge has a transmission zero. Using accurate equivalent circuit modeling and even-odd mode analysis, the operating principle is discussed. The article also includes a general design flowchart and two additional designs. To verify its performance, an X-band prototype has been fabricated and measured, and the results are in good accordance with the simulation results. A prototype at X-band is analyzed, fabricated and measured, showing the passband center frequencies of 9.68 GHz and 10.73 GHz, fractional bandwidths of 3.45% and 3.48%, and insertion losses of 0.9 dB and 1.1 dB, respectively. The structure proposed in this paper has a low profile and design difficulty, a small frequency ratio, high cross-polarization isolation, and out-of-band suppression in comparison to existing literature. Therefore, this design has the potential as a device for contemporary wireless communication systems. Our future work will aim to design frequency- and polarization-selective surfaces with higher order and wider bandwidth by introducing additional structures, i.e., symmetrical microstrip branches and grounded vias. Moreover, attempts will be made to realize metasurface designs with linearly polarized rotation properties by utilizing double-layered asymmetric structures. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Reference** & **Technology** & **C.F (GHz)** & **FBW (\%)** & **Worst IL ** & **Profile** & **TZ** \\ \hline
[29] &
\begin{tabular}{c} Cylindrical \\ dielectric \\ resonators \\ \end{tabular} & 7.48\(\pm\)11 (TE) & 17.56\(\pm\)14.5 (TE) & 0.9 & 30 & 4 & 2 & 2 \\
[33] & \
\begin{tabular}{c} Jerusalem \\ cross \\ \end{tabular} & 7.36\(\pm\)26.9 (TE) & 21.56\(\pm\)11.3 (TE) & 1.2 & 13.7 &
\begin{tabular}{c} \(1.0*2\) \\ \(0.05\lambda_{0}/0.076\lambda_{0}\) \\ \end{tabular} & 2 & 0 \\ \hline
[34] & \
\begin{tabular}{c} Patch with \\ twisted slot \\ \end{tabular} & 8.2/13.58 & 16/4.5 & 2.4 & 14.2 &
\begin{tabular}{c} \(1.5*2\) \\ \(0.08\lambda_{0}/0.14\lambda_{0}\) \\ \end{tabular} & 2 & 0 \\ \hline
[46] & \
\begin{tabular}{c} Patch \\ resonator \\ \end{tabular} & 3.34/4.41 & 9/4.5 & 2 & 19.5 &
\begin{tabular}{c} \(3.15\) \\ \(0.035\lambda_{0}/0.05\lambda_{0}\) \\ \end{tabular} & 2 & 0/2 \\ \hline
[47] & \
\begin{tabular}{c} Multi- \\ mode \\ patch \\ \end{tabular} & 3.03/4.33 & 2.44/2.46 \({}^{3}\) & 1.06 & 12 &
\begin{tabular}{c} \(3.1\) \\ \(0.32\lambda_{0}/0.44\lambda_{0}\) \\ \end{tabular} & 2 & 1 \\ \hline
[48] & \
\begin{tabular}{c} Cross- \\ dipole, \\ loop \\ \end{tabular} & 15/23 (Sim. \({}^{4}\)) & 10.7/11.7 & - &
\begin{tabular}{c} \(>\)12 \\ \(0.05\lambda_{0}/0.08\lambda_{0}\) \\ \end{tabular} & 2 & 4 \\ \hline
[49] & \begin{tabular}{c} Cross- \\ dipole, \\ loop \\ \end{tabular} & 16/28 (Sim.) & 35/45 (Sim.) & 0.9 \(\sim\) 1.4 (Sim.) & \begin{tabular}{c} \(>\)20 \\ \(0.4\lambda_{0}/0.7\lambda_{0}\) \\ \end{tabular} & 2 & 0 \\ \hline This work & \
\begin{tabular}{c} Grounded \\ U-shaped \\ resonator \\ \end{tabular} & 9.68/10.73 & 3.45/3.48 & 1.1 & 30 &
\begin{tabular}{c} \(1.07\) \\ \(0.03\lambda_{0}/0.036\lambda_{0}\) \\ \end{tabular} & 2 & 2 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Performance comparisons of the fabricated X\(-\)band FSS with other state of the art similar works. **Author Contributions:** Conceptualization, T.Q. and Y.C. ; methodology, T.Q. ; software, C.H. ; validation, C.H., X.L. and T.Q. ; formal analysis, T.Q. and C.H. ; investigation, X.L. and Y.C. ; resources, Y.C. ; data curation, T.Q. and C.H. ; writing--original draft preparation, T.Q. and C.H. ; writing--review and editing, C.H. and Y.C. ; visualization, Y.C. and X.L. ; supervision, X.L. ; project administration, X.L. ; funding acquisition, X.L. and Y.C. All authors have read and agreed to the published version of the manuscript.