# Dual-Polarized Multi-Beam Fixed-Frequency Beam Scanning Leaky-Wave Antenna
## 4 Conclusions  
An SPPs LWA array with dual-polarized, switchable, and steerable multi-beam at fixed frequency is proposed. In the frequency range of 3.3-3.8 GHz, this antenna has the capability to modify the voltage loaded on the varactor diode to achieve a maximum scanning range of 35\({}^{\circ}\) for multi-beams and 55\({}^{\circ}\) for single-beams. Additionally, the beam width is adjustable by switching between the multi-beam and single-beam modes. The peak gain of this antenna is 12.1 dBi, while the radiation efficiency exceeds 60%. Given these capabilities, this antenna holds great potential for use as a relay antenna in future satellite communication within the SAGIN. The antenna's measured results exhibit excellent agreement with the simulated results, validating its superior performance.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Ref.**} & \multirow{2}{*}{\begin{tabular}{c} **Freq.** \\ **(GHz)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Length** \\ **(\(\lambda_{0}\))** \\ \end{tabular} } & \multirow{2}{*}{**Polarization**} & \multicolumn{2}{c}{\begin{tabular}{c} **Beam** \\ **Width** \\ **Tuning** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Scanning** \\ **Mode** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **Beam** \\ **Scanning** \\ **Range** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Maximum** \\ **Gain** \\ **(dBi)** \\ \end{tabular} } \\ \hline
[12] & 5.5–5.8 & 6.2 & Single & No & Single-beam & 45\({}^{\circ}\) & 8 \\ \hline
[13] & \begin{tabular}{c} 4–4.5 \\ and 5.75–7.25 \\ \end{tabular} & \
\begin{tabular}{c} 4.65 \\ and 7.15 \\ \end{tabular} & Single & No & Single-beam &
\begin{tabular}{c} 80\({}^{\circ}\) \\ and 22\({}^{\circ}\) \\ \end{tabular} & 13.8 \\ \hline
[14] & 4.75–5.25 & 2.6 & Single & No & Single-beam & 69\({}^{\circ}\) & 6.4 \\ \hline
[15] & 2.45 & 2.29 & Single & Yes & Single-beam & 50\({}^{\circ}\) & 8 \\ \hline
[16] & 3.4–3.7 & 5.4 & Dual & No & Single-beam & 39\({}^{\circ}\) & 9.7 \\ \hline This work & 3.3–3.8 & 5.6 & Dual & Yes & \
\begin{tabular}{c} Single-beam and \\ Multi-beam \\ \end{tabular} &
\begin{tabular}{c} 55\({}^{\circ}\) \\ and 35\({}^{\circ}\) \\ \end{tabular} & 12.1 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Comparison of the proposed LWA with the reported references.  
Figure 11: Radiation efficiency of the dual-polarized antenna. (a) X-polarized antenna, (b) Y-polarized antenna.  
**Author Contributions:** Conceptualization, Y.Z.; data curation, H.L.; formal analysis, D.C.; funding acquisition, Y.Z.; investigation, H.L.; methodology, D.C.; project administration, Y.M. and Y.Z.; resources, Y.M., H.B. and Y.Z.; validation, H.B. and Y.Z.; writing--original draft, D.C. and H.L.; writing--review and editing, D.C., Y.M., H.B. and Y.Z. All authors have read and agreed to the published version of the manuscript.  
**Funding:** National Natural Science Foundation of China (61971469); Fundamental Research Funds of Shaanxi Key Laboratory of Artificially-Structured Functional Materials and Devices (AFMD-KFJ)-21105.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**Conflicts of Interest:** The authors declare no conflict of interest.