## 9 Effect of PIN Diode Equivalent Resistor on the Beamwidth Control
In [32], the authors presented a similar design to this work, albeit using a non-transparent substrate (Rogers) with an opaque structure. Additionally, they did not propose any control of the beam tilt (which only has 3 directions), beamwidth control, or state combination. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Configuration** & **State** & **D1** & **D2** & **D3** & **Beam Characteristic** \\ \hline
1 & State 1 & ON & ON & OFF & Broadside 0\({}^{\circ}\) \\ \hline
2 & State 2 & OFF & ON & ON & +90\({}^{\circ}\) left \\ \hline
3 & State 3 & ON & OFF & ON & \(-\)90\({}^{\circ}\) right \\ \hline
4 & State 4 & OFF & OFF & OFF & large \\ \hline
5 & State 1 + 2 & OFF & OFF & ON & +45\({}^{\circ}\) tilt \\ \hline
6 & State 1 + 3 & OFF & ON & OFF & \(-\)45\({}^{\circ}\) tilt \\ \hline
7 & State 2 + 3 & ON & OFF & OFF & Bidirectional \(\pm\)90\({}^{\circ}\) \\ \hline
8 & \begin{tabular}{c} State 1 \\ (R\({}_{1}\)-IN-R\({}_{2}\)) \\ \end{tabular} & \begin{tabular}{c} Variable diode \\ equivalent \\ resistor R\({}_{1}\) \\ \end{tabular} & \
\begin{tabular}{c} Variable diode \\ equivalent \\ resistor R\({}_{2}\) \\ \end{tabular} & OFF &
\begin{tabular}{c} Control of beamwidth \\ around 0\({}^{\circ}\) \\ \end{tabular} \\ \hline
9 & \begin{tabular}{c} State 2 \\ (IN-R\({}_{3}\)-R\({}_{2}\)) \\ \end{tabular} & OFF & \begin{tabular}{c} Variable diode \\ equivalent \\ resistor R\({}_{2}\) \\ \end{tabular} & \
\begin{tabular}{c} Variable diode \\ equivalent \\ resistor R\({}_{3}\) \\ \end{tabular} &
\begin{tabular}{c} Control of beamwidth \\ around +90\({}^{\circ}\) \\ \end{tabular} \\ \hline
10 & \begin{tabular}{c} State 3 \\ (R\({}_{1}\)-R\({}_{3}\)-IN) \\ \end{tabular} & \begin{tabular}{c} Variable diode \\ equivalent \\ resistor R\({}_{1}\) \\ \end{tabular} & OFF & \
\begin{tabular}{c} Variable diode \\ equivalent \\ resistor R\({}_{3}\) \\ \end{tabular} &
\begin{tabular}{c} Control of beamwidth \\ around \(-\)90\({}^{\circ}\) \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Summarized Configuration states. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Ref.** & **Antenna** & **Method** & \begin{tabular}{c} **RF** \\ **Component** \\ \end{tabular} & \
\begin{tabular}{c} **BW** \\ **(\%)** \\ \end{tabular} & **No. of States** &
\begin{tabular}{c} **Coverage** \\ **Angle** \\ \end{tabular} & **Gain (dBi)** \\ \hline
[6] & Patch & Parasitic tuning & 4 PIN diodes & 0.6 & 9 & 30\({}^{\circ}\) & 7 \\ \hline
[13] & Patch & Parasitic tuning & 3 PIN diodes & 23.5 & 2 &
\begin{tabular}{c} Conical/broadside \\ \end{tabular} & 6.9–8.2 \\ \hline
[15] & Patch & Parasitic tuning & 12 PIN diodes & 14.5 & 6 & 360\({}^{\circ}\) & 10 \\ \hline
[16] & Planar & Switchable stubs & 4 PIN diodes & 6.1 & 4 & 90\({}^{\circ}\) & 5 \\ \hline
[17] & Monopole & Multiple radiators & 4 PIN diodes & 34 & 4 & 90\({}^{\circ}\) & 2.8–3.7 \\ \hline
[23] & Patch & Multiple radiators & 16 PIN diodes & 2.6 & 16 & 22.5\({}^{\circ}\) & 4.4–6 \\ \hline
[24] & Dipole & Parasitic tuning & 16 PIN diodes & 8 & 5 & 45\({}^{\circ}\) & 5.2–6.5 \\ \hline
[32] & \
\begin{tabular}{c} Triple \\ Vivaldi \\ \end{tabular} &
\begin{tabular}{c} Non-transparent \\ microstrip line \\ \end{tabular} & 3 PIN diode & 70 & 3 & 300\({}^{\circ}\) & 5.5 \\ \hline
[33] & Cone & Parasitic reflectors & Liquid metal & 45.5 & 4 & 30\({}^{\circ}\) & 6.7 \\ \hline
[34] & Tapered slot & Multiple radiators & 4 PIN diodes & 71 & 2 & 90\({}^{\circ}\) & 6.4 \\ \hline
[35] & Patch & Parasitic tuning & 6 PIN diodes & 29 & 12 & 30\({}^{\circ}\) & 8 \\ \hline This work & \
\begin{tabular}{c} Triple \\ Vivaldi \\ \end{tabular} &
\begin{tabular}{c} Transparent \\ microstrip line \\ \end{tabular} & 3 PIN diodes & 66.7 & 10 & 300\({}^{\circ}\) & 6.45 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Beam switching and bandwidth improvement design summary. In [33], the authors used a liquid metal to switch between four states, but the antenna achieved a coverage of only 30\({}^{\circ}\).