# Methodology for Improving Scanning Performance Loading an Array Element with a 3D All-Metal WAIM
## 4 Conclusions  
In this contribution, a 3D all-metal unit-cell has been characterized for oblique incidence and in the two main scanning planes. Its successful characterization allows its use in applications requiring a wide scanning angle, such as the WAIM application. Additionally, a new methodology based on the use of an EC has been described, which drastically reduces the total number of needed full-wave simulations. It has been tested with a phased array made of metallic horns, showing a more than 5 dB improvement in the _H-plane_, for \(\theta\) angles larger than \(35^{\circ}\). This optimal result was obtained for an extremely small spacing between the WAIM and the antenna, which suggests there could be some interest in integrating the 3D matching structure with the antenna. It was also demonstrated that the agreement provided by the EC gets better when the spacing is increased, due to the used assumptions in the modeling. The methodology may be further improved by following other approaches, such as the mode-matching technique at the cost of increased complexity. Future works will focus on the simultaneous matching of _E-_ and _H-planes_ as well as dual-polarization performance. Conceptualization, D.B.-M., M.G.-V., R.G., H.L. and C.M. (Section 2); methodology, D.B.-M., M.G.-V., R.G. and H.L. (Section 3); introduction and conclusion, D.B.-M., M.G.-V. and R.G. (Sections 1 and 4). All authors reviewed and edited the document. All authors have read and agreed to the published version of the manuscript. This publication is supported by the European Union through the European Regional Development Fund (ERDF), and by the french region of Brittany, Ministry of Higher Education and Research, Rennes Metropole and Conseil Departemental 35, through the CPER Project SOPHIE/STIC & Ondes and also by Thales Alenia Space and Region Bretagne. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & \multicolumn{1}{c}{**Matching Range**} & \multicolumn{1}{c}{**Dual Scanning Plane**} & \multicolumn{1}{c}{**WAIM Type**} \\  & **Improvement** & **Performance** & **WaIM Type** \\ \hline
[25] &
\begin{tabular}{c} _-H-plane_ improved up to \(\theta=56^{\circ}\). \\ _-E-plane_ already matched at \(\theta=56^{\circ}\) \\ (almost unmodified). \\ _-H-plane_ improved at \(\theta=70^{\circ}\) from \\ \(\Gamma_{in}=-7\ dB\) to \(\Gamma_{in}=-12\ dB\). \\ _-E-plane_ already matched at \(\theta=70^{\circ}\). \\ _-H-plane_ scans up to \(\theta=50^{\circ}\). \\ _-E-plane_ scans up to \(\theta=60^{\circ}\). \\ No results shown without WAIM. \\ \hline
[33] &
\begin{tabular}{c} _-H-plane_ is matched up to \(\theta=55^{\circ}\). \\ _-E-plane_ is not shown. \\ _-H-plane_ improved from \(\theta=52^{\circ}\) to \\ _-D-plane_ improved from \(\theta=62^{\circ}\) to \\ _-E-plane_ does not vary. \\ _-D-plane_ is not shown. \\ _-D-plane_ is not shown. \\ _-D-plane_ improved from \(\theta=62^{\circ}\) to \\ _-E-plane_ does not vary. \\ _-D-plane_\(\phi=0^{\circ}\rightarrow\theta=80^{\circ}\). \\ _-D-plane_\(\phi=45^{\circ}\rightarrow\theta=75^{\circ}\). \\ _-D-plane_\(\phi=90^{\circ}\rightarrow\theta=77^{\circ}\). \\ Without WAIM the antenna is unmatched. \\ \hline
[35] &
\begin{tabular}{c} Compensates mismatching \\ produced by back reflector. \\ _-H-plane_ up to \(\theta=50^{\circ}\). \\ _-E-plane_ up to \(\theta=50^{\circ}\). \\ _-S_canning up to \(\theta=60^{\circ}\) (not specifying \\ the scanning plane). \\ _-Improving the gain of the antenna_ \\ between 3 to 5 dB. \\ \hline
[37] & \begin{tabular}{c} _-H-plane_ improved up to \(\theta=81^{\circ}\). \\ _-E-plane_ improved up to \(\theta=67^{\circ}\). \\ _-E-plane_ improved up to \(\theta=55^{\circ}\). \\ _-E-plane_ degraded. \\ \end{tabular} & \
\begin{tabular}{c} Affects 2 planes for 1 polarization. \\ (dielectric + metal). \\ \end{tabular} &
\begin{tabular}{c} 3D WAIM \\ (dielectric + metal). \\ \end{tabular} \\ \hline
**Loaded TEM unit-cell** & _-H-plane_ improved up to \(\theta=55^{\circ}\). \\ **(this work)** & _-E-plane_ degraded. \\ \hline \hline \end{tabular}
\end{table}