# A Compact Planar Wi-Fi Antenna with Optimized Radiation Patterns for Small UAV Applications
## 5 Conclusions  
In summary, we proposed a compact planar Wi-Fi antenna with optimized radiation patterns for small UAV applications in urban and open areas. The proposed antenna was prototyped and measured, and the measured results agree with the simulated data. It has end-fire radiation to reduce the interference from rare-use directions at 5.8 GHz and quasi-omnidirectional radiation to ensure a stable link in all directions at 2.4 GHz. The directions of the maximum radiation in each elevation plane at 5.8 and 2.4 GHz provide more antenna gain when the small UAV flies farther in urban and open areas. In future work, the proposed antenna will be mounted on a small UAV for field experiments.  
Conceptualization, Y.-L.Y. and D.-B.L.; methodology, Y.-L.Y. and D.-B.L.; software, Y.-L.Y.; validation, Y.-L.Y. and D.-B.L.; formal analysis, Y.-L.Y. and D.-B.L.; investigation, Y.-L.Y. and D.-B.L.; resources, D.-B.L.; data curation, Y.-L.Y. and D.-B.L.; writing--original draft, Y.-L.Y.; writing--review and editing, D.-B.L.; visualization, Y.-L.Y.; supervision, D.-B.L.; project administration, D.-B.L. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the Ministry of Science and Technology of Taiwan under Grant MOST 110-2221-E-011-052.  
Not applicable.  
**Data Availability Statement:** All the design parameters and related data are provided in this article.  
**Conflicts of Interest:** The authors declare no conflict of interest.  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & \multirow{2}{*}{**Unit: Degree**} & \multicolumn{6}{c}{**Y-z Plane**} & \multicolumn{6}{c}{**x-z Plane**} \\ \cline{3-10}  & & & **Left Plane** & **Right Plane** & **Left Plane** & **Right Plane** \\ \hline \multirow{4}{*}{2.4 GHz} & Maximum gain angle & \(-98\) & \(98\) & \(-95\) & \(91\) & \\ \cline{2-10}  & Relative & Beam angle & \(-142\) & \(-49\) & \(48\) & \(142\) & \(-139\) & \(-49\) & \(46\) & \(134\) \\ \cline{2-10}  & Beamwidth & \(93\) & \(94\) & \(90\) & \(88\) & \\ \cline{2-10}  & Relative & Beam angle & \(-165\) & \(-20\) & \(19\) & \(165\) & \(-165\) & \(-21\) & \(18\) & \(160\) \\ \cline{2-10}  & Beamwidth & \(145\) & \(146\) & \(144\) & \(142\) & & \(142\) & \\ \hline \multirow{4}{*}{5.8 GHz} & Maximum gain angle & \(-61\) & \(62\) & \(-76\) & \(73\) & \\ \cline{2-10}  & Relative & Beam angle & \(-102\) & \(-29\) & \(29\) & \(103\) & \(-118\) & \(-39\) & \(37\) & \(114\) \\ \cline{2-10}  & \(-3\) dB & Beamwidth & \(72.96\) & \(74\) & \(79\) & & \(77\) & \\ \cline{2-10}  & Relative & Beam angle & \(-127\) & \(-11\) & \(11\) & \(129\) & \(-152\) & \(-16\) & \(14\) & \(148\) \\ \cline{2-10}  & \(-10\) dB & Beamwidth & \(116\) & \(118\) & \(136\) & & \(134\) & \\ \hline \hline \end{tabular}
\end{table}
Table 2: Characteristics of the simulated vertically polarized radiation patterns.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Ref.** & **Structure** & **Operating** & **Radiation Pattern** & **Electrical Dimensions** \\  & & **Frequency** & **for Urban Areas** & **for Open Areas** & **(L\(\times\)W\(\times\)h) (\(\lambda_{0}\))** \\ \hline \multirow{4}{*}{[11]} & Double-sided & \(0.86\) to \(1.51\) & & Yes & \(0.3297\times 0.0344\times 0.0046\) \\  & Double-sided & \(3.9\) to \(5\) & & Yes & \(2.3400\times 0.1820\times 0.0260\) \\ \cline{1-1} \cline{1-1}  & Single-sided & \(3.5/3.7/4.5/5/5.7\) & Yes & Yes & \(0.4690\times 0.1470\times 0.0092\) \\ \cline{1-1}  & Single-sided & \(2.4\) to \(5.8\) & & Yes & \(0.1600\times 0.2000\times 0.0128\) \\ \cline{1-1} \cline{2-10}  & Single-sided & \(2.4/5.8\) & Yes & Yes & \(0.1320\times 0.2424\times 0.0128\) \\ \hline \hline \end{tabular}
\end{table}
Table 3: The comparison of the proposed antenna and published works on planar antennas.