## 6 Beam Steering Results  
One possible application for this MS type is a reconfigurable steering reflector for radiation, which impinges the MS with polarization, as shown in Figures 2 and 5. For each operating frequency, the phase calibration curve allows for extracting the appropriate DC reverse biases for each column, which leads to the required phase difference, \(\Delta\phi\), between the columns, thus creating the desired phase distribution on the MS reflector for the planned beam steering angle \(\theta\) as described in Figure 2 and according to Equation (8), where \(\Delta X=4.2\) mm is the unit cell size. The beam steering results at 11 GHz, 12 GHz, and 13.5 GHz for the normal incident are shown in Figure 15.  
In Figure 15, for each frequency RCS results set, the black dashed curve is the theoretical upper limit of the steering ability of the relevant frequency. This upper limit is proportional to \(cos(\theta)\)[38] and was extracted from the unit cell properties via CST using the active element impedance method [39]. The result for the copper surface in the same  
Figure 14: Reflection losses in the operating frequencies as a function of the reflection phase: (**a**) at 11 GHz, (**b**) at 12 GHz, and (**c**) at 13.5 GHz.  
MS size for reference purposes is in the grey curves, and the result for the MS without phase manipulation is in the red curve when both RCS peaks were at angle \(\theta\) = 0\({}^{\circ}\). The MS beam steering results for several \(\theta\) angle values, as an example, are in the blue curves. For a planar square reflector, the far-field pattern is proportional to the sinc function. The sinc profile is narrow for a wide size surface and wide for a narrow surface [47]. In this case, the MS reflector size was constant and the wavelengths for each frequency were different; therefore, the profile of the main lobe at 13.5 GHz was narrower than the 11 GHz main lobe, but it depended on the array size rather than an inherent issue.  
The steering results improved significantly as the working frequency increased, as shown in Figure 15 and Tables 1-3. The RCS peak of the steering results at 11 GHz was about 5 dB lower than the theoretical upper limit because of the high losses, which were mainly attributed to the diode. This gap closed as the operating frequency increased to  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \(\theta\) **Calc/Sim (\({}^{\circ}\))** & **SLL (dB)** & **RCS peak (dB)** & **Efficiency** \\ \hline \(0^{\circ}\)/\(0^{\circ}\) & \(13.3\) & \(0\) & \(1\) \\ \(0^{\circ}\)/\(0^{\circ}\) & \(13.4\) & \(-1.14\) & \(0.767\) \\ \(10^{\circ}\)/\(9.3^{\circ}\) & \(5.58\) & \(-6.64\) & \(0.217\) \\ \(30^{\circ}\)/\(28.05^{\circ}\) & \(2.17\) & \(-8.13\) & \(0.154\) \\ \(50^{\circ}\)/\(51.33^{\circ}\) & \(1.31\) & \(-10.09\) & \(0.098\) \\ \hline \hline \end{tabular}
\end{table}
Table 1: Parameters for steering angles \(\theta\) at 11 GHz.  
Figure 15: Far-field simulation results for MS reflector: (**a**) at 11 GHz, (**b**) at 12 GHz, and (**c**) at 13.5 GHz.  
\(12\) GHz and \(13.5\) GHz. The steering angle in the simulation was very close to the calculated angle, and the efficiency decreased as a function of the steering angle \(\theta\).