## 9 Effect of PIN Diode Equivalent Resistor on the Beamwidth Control  
The radiation beams emitted in state 1 exhibit higher directionality compared to the other two states. This is attributed to the ground plane's improved reflectivity in state 1. In order to achieve a balanced radiation performance across all states in our proposed structure, we adjusted the bias values of the PIN diodes to function as variable resistors. The dynamic resistor characteristics, a function of DC bias, are illustrated in Figure 17.  
The radiation patterns of state 1 are compared with the different diode biasing configurations in state 3. In the notion X-IN-X, X represents the value of the equivalent resistor diode, while IN denotes an infinite value of the equivalent diode resistor (\(>\)6000 \(\Omega\) for no bias). According to Figure 18, we have the ability to regulate the aperture of the beam. When the resistor value is X = 0.01 \(\Omega\), the beamwidth is 75\({}^{\circ}\) at \(-3\) dB. Conversely, when the resistor value is 200 \(\Omega\), the beam aperture increases to 155\({}^{\circ}\), which is approximately twice the level of the previous value. Table 3 illustrates the values of the resistors and their corresponding \(-3\) dB beamwidth angles. The same behavior can be applied to states 2 and 3. Figure 16: (a) Polar plot of all three states (E\({}_{\varphi}\) versus \(\varphi\)). (b) Combination of state 1 results in a change in the direction of the beam (E\({}_{\varphi}\) versus \(\varphi\)). Figure 17: Diode resistance versus DC diode curent polarization. The yellow circles correspond to values of 6000, 200, 150, 60, 50, 20, and 0.01 ohms. Section 8 demonstrates that, with regard to configuration 1, the coverage can be further increased by controlling the diode resistor states. Additionally, a null value can be created in a specific direction. For example, this occurs in state 2 (IN-200-200, that mean IN > 6000 \(\Omega\), and 200 \(\Omega\)), while state 1 or state 3 exhibit a maximum response at a 305\({}^{\circ}\) direction, as illustrated in Figure 19. The purple curve correspond to \(-3\) dB reference level indicator. This configuration can be particularly useful in applications such as direction of arrival (DOA) estimation. Table 4 provides a summary of all of the configuration cases. Configurations 8 to 10 offer significant control over the beamwidth. Figure 19: Coverage enhancement using state 1, state 2, and state 3 with special diode resistor values (E\(\varphi\) versus \(\varphi\)). \begin{table}
\begin{tabular}{c c} \hline \hline
**R = R\({}_{2}\) = R\({}_{3}\)** & \(\theta\)\({}_{-34\text{B}}\) \\ \hline
0 & 75 \\ \hline
20 & 84 \\ \hline
50 & 99 \\ \hline
60 & 104 \\ \hline
150 & 145 \\ \hline
200 & 155 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The summary of \(-3\) dB beamwidth controlled by equivalent resistor diodes D2 and D3 while D3 is off (high equivalent resistor value). Figure 18: State 1 exhibits varying diode resistor values (E\({}_{\varphi}\) versus \(\varphi\)). Table 5 provides a comparison between the presented antennas and recently published pattern-reconfigurable antennas. In [6], four PIN diodes were used to achieve nine states, but the coverage was limited to 30\({}^{\circ}\). Ref. [13] used three PIN diodes but achieved only two distinct states and covered just conical and broadside aspects. In [15], the authors achieved a coverage angle of 360\({}^{\circ}\) but utilized 12 PIN diodes. In [16; 17], the antennas are larger in size compared to this design, have only four working modes, and cover only 6.7% of bandwidth in [16] and 34% in [17]. Similarly, ref. [23] used 16 PIN diodes to cover only 22.5\({}^{\circ}\). In [24], the authors also employed 16 PIN diodes to achieve 8% on bandwidth and a coverage of only 45\({}^{\circ}\). In contrast, our design successfully achieved more than 10 states, with just 3 diodes used as ON/OFF switches and variable resistors.