# Generation of Beam Tilt through Three-Dimensional Printed Surface
## 4 Results and Discussion
### Radiated Beam Patterns with BDS Surface  
The defined four-layer BDS structure is able to deviate the beam to the fixed elevation angle (\(\theta\)) where as its counter rotation shows the different azimuth angle (\(\phi\)). We have considered four different orientation angles as of 0\({}^{\circ}\), 90\({}^{\circ}\), 180\({}^{\circ}\), and 270\({}^{\circ}\) rotated counter-clockwise direction where the respective peak radiation patterns deviate, as shown in Figure 14a-f for 10, 11, 12, 13, 14 and 15 GHz, respectively. Firstly, the orientation of 0\({}^{\circ}\) indicates the placement of BDS along the E-plane where the phase gradient increases from bottom to top. Afterward, this BDS surface is counter-rotated in steps of 90\({}^{\circ}\) so that we will have another three orientations that will indicate 90\({}^{\circ}\), 180\({}^{\circ}\), and 270\({}^{\circ}\) positions. As noted in Figure 14a-f, the beam direction is opposite for 0\({}^{\circ}\) and 180\({}^{\circ}\) orientations, and similar opposite patterns are observed for 90\({}^{\circ}\) and 270\({}^{\circ}\) orientations. Figure 13: Block diagram with fabricated BDS prototype. (**a**) System setup block diagram. (**b**) Fabricated BDS prototype connected to 3D printed horn antenna as set up in a measurement chamber. In order to verify our design concept for BDS beam deviation, we have chosen the 270\({}^{\circ}\) orientation and have compared the measured results, as shown in Figure 15a-e, respectively, for frequencies of 11, 11.5, 12, 12.5 and 13 GHz. In the 270\({}^{\circ}\) orientation of BDS, the main lobe values obtained for 11, 11.5, 12, 12.5 and 13 GHz are respectively 16.2, 16.7, 18.5, 16.4 and 17.9 dBi, respectively, where the main lobe directions are in \(-27^{\circ}\), \(-24^{\circ}\), \(-22^{\circ}\), \(-20^{\circ}\) and \(-15^{\circ}\) in which the negative sign indicates the beam direction in the opposite direction. Similarly, the side lobe levels as noted for 11, 11.5, 12, 12.5 and 13 GHz are, respectively, \(-4.6\), \(-4.7\), \(-4.9\), \(-3.4\) and \(-4.5\) dBi. The measured peak value is slightly deviated from the simulated values for 11, 11.5, 12, 12.5 and 13 GHz frequencies because of error in alignment of the BDS surface during measurement steps. However, the figures as depicted from Figure 15a-e show the similarity obtained for the deviation of beam as compared against the simulated patterns. Figure 14: Simulated E-field radiation patterns as observed with the use of the BDS prototype kept above the feed horn: (**a**) 10, (**b**), 11 (**c**), 12 (**d**), 13 (**e**), 14, (**f**) 15 GHz. Similarly, we have plotted the voltage standing wave ratio (VSWR), as shown in Figure 16, where it shows the wideband nature of the proposed BDS prototype with values less than two through the operating frequency range. The measured VSWR condition for the 270\({}^{\circ}\) orientation case is also shown, which depicts the matching of the proposed BDS prototype. Figure 15: Simulated and measured E-field radiation patterns as well as cross polarization values as observed with the use of the BDS prototype above the feed horn for 270\({}^{\circ}\) orientation (**a**) 11, (**b**) 11.5, (**c**) 12, (**d**) 12.5, (**e**) 13 GHz. Table 1 presents the performance comparison of the proposed beam tilting prototype with existing state-of-the-art work presented in the literature. It shows that the wideband tilting feature lies within the Ku-band operation covering from 10 to 15 GHz. There is no relative gap between the BDS prototype and feed horn, which eventually decreases the overall height of the designed antenna system. The peak gain is maintained for around 18.5 dBi and is comparatively smaller in aperture dimension. Figure 16: Simulated and measured VSWR of proposed BDS prototype. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Ref. **} & \multirow{2}{*}{ \begin{tabular}{c} **Operating** \\ **Hand Width** \\ **(GHz)** \\ \end{tabular}  } & \multirow{2}{*}{