## 5 Conclusions  
In this study, we have presented the use of additive manufacturing techniques for steering the beam direction. The use of parallel plates eventually decreased the profile of the Luneburg lens and the respective arrangement of cylindrical rods shows the steering characteristics, as shown from 10 GHz to 15 GHz. The measured directivity and gain values are relatively higher which are of around 14.7 and 12.7 dBi. The parallel plate structure has been excited in the dominant mode of TE\({}_{10}\) with reasonably good results in radiation patterns with lower side lobe levels and less cross polarization values that are of below \(-6\) dB and \(-15\) dBi, respectively. The weight of the overall proposed system is about 179 g, which shows the systems are light in weight. Similarly, the simulated and measured VSW plots are less than 2.2 over the frequency of interest. This signifies the matching over the operating frequency range that cover the Ku-band region.  
Conceptualization, S.S.; Data curation, S.S.; Formal analysis, S.S.; Investigation, S.S.; Methodology, S.S.; Project administration, S.S.; Resources, S.S.; Software, S.S.; Validation, S.S.; Visualization, S.S.; Writing-original draft, S.S.; Funding acquisition, S.M.A., M.A. and K.P.E.; Supervision, S.M.A., M.A. and K.P.E.; writing--review and editing, S.S., M.A., M.A. and K.P.E. All authors have read and agreed to the published version of the manuscript.  
This work was supported in part by the Australian Research Council (ARC), and in part by the Macquarie University International Research Excellence Scholarship (iMQRES), 45035091.  
Not applicable.  
We want to extend thankfulness to CSIRO, Marsfield, NSW, Australia and Macquarie University for providing support for measurement of antenna prototype.  
The authors declare no conflict of interest.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Ref.** & \begin{tabular}{c} **Peak Gain** \\ **(dBi)** \\ \end{tabular} & \begin{tabular}{c} **Peak Directivity** \\ **(dBi)** \\ \end{tabular} & \begin{tabular}{c} **Bandwidth** \\ **(GHz)** \\ \end{tabular} & \begin{tabular}{c} **Side Lobe Level** \\ **(dB)** \\ \end{tabular} & \
\begin{tabular}{c} **Dimension** \\ **(mm)** \\ \end{tabular} &
\begin{tabular}{c} **Fabrication** \\ **Method** \\ \end{tabular} \\ \hline
[11] & 14 & \
\begin{tabular}{c} 12.5 \\ (in 13 GHz) \\ \end{tabular} & 12.5 to 13.5 & n/a & 151.2 (6.3 \(\lambda\)) &
\begin{tabular}{c} Printed circular \\ patches \\ \end{tabular} \\ \hline
[13] & 20 & n/a & 26 to 40 & \(-14\) & 50 (4.33 \(\lambda\)) &
\begin{tabular}{c} Metallic \\ posts \\ \end{tabular} \\ \hline
[16] &
\begin{tabular}{c} 14.5 \\ (in 36.5 GHz) \\ \end{tabular} & n/a & 35 to 40 & less than \(-9\) & 60 (7 \(\lambda\)) & Teflon \\ \hline
[19] & \
\begin{tabular}{c} 14.6 (in 23.5 GHz) \\ 16.3 (in 26 GHz) \\ 16.1 (in 28 GHz) \\ \end{tabular} & n/a & 23.5 to 28 &
\begin{tabular}{c} \(-11.9\) (in 23 GHz) \\ \(-12.5\) (in 26 GHz) \\ \end{tabular} & 300 (23.49 \(\lambda\)) & Vero Clear \\ \hline
[20] & 12.5 & n/a & 3.8 to 4.4 & n/a & 360 (4.56 \(\lambda\)) & Epoxy posts \\ \hline Proposed & \begin{tabular}{c} 12.7 \\ (in 14 GHz) \\ \end{tabular} & \
\begin{tabular}{c} 14.7 \\ (in 13 GHz) \\ \end{tabular} & 10 to 15 & less than \(-6\) & 100 (3.33 \(\lambda\)) &
\begin{tabular}{c} Multijet \\ 3D printing \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table}
Table 1: Comparison of proposed antenna structure.