## 3 Design Methodology
### Switching Effects  
The proposed antenna performance is reconfigured by introducing four LDR diodes to control the frequency resonances. We found such a technique is very applicable to controlling the generated frequency bands by controlling the current motion [2]. In our study, we selected four cases only as summarized in Table 1. The antenna performances in terms of S\({}_{11}\) and gain spectra are presented in Figure 6. The antenna gain is found to be insignificantly affected by changing the diode's operation due to the fact of coupling effects between the antenna transmission line and the proposed SRR unit cells. The rest of the other cases are not considered in this study due to space limitations. It is good to mention the activation of the LDR diode by applying a biasing voltage to obtain a logic_1. In case of deactivating the LDR diode, a logic_0 can be obtained.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \(\mathbf{R_{1}}\) & \(\mathbf{R_{2}}\) & \(\mathbf{R_{3}}\) & \(\mathbf{R_{4}}\) & \(\mathbf{Frequency/GHz\ @\ S_{11}\leq-10\ dB}\) & **Gain/dBi** \\ \hline
0 & 0 & 0 & 0 & 1.8, 3.3, 4.8, 5.5, 5.8 & 9.8, 10.8, 2, 0, 9.9 \\ \hline
1 & 1 & 0 & 0 & 2.5, 3.9, 4.8 & 2.7, 4.1, 3.8 \\ \hline
0 & 0 & 1 & 1 & 1.3, 2.1, 2.8, 3.9, 4.8, 5.8 & 1.7, 2.7, 2.3, 4, 3.5, 3.7 \\ \hline
1 & 1 & 1 & 1 & 2.5, 3.9, 4.8 & 2.9, 4, 11.6 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Comparison between the switching scenarios operation in terms of antenna performance.  
Figure 5: Antenna performance varying the ground plane length: (**a**) S\({}_{11}\) spectra and (**b**) gain.  
Another study is applied in this section; the proposed antenna performance based on LDR switches is studied by varying the LDR resistance value from 0 \(\Omega\) to 700 \(\Omega\). In such a study, the proposed antenna is switched by changing the resistance level for all LDR resistors at the same time. This is because the antenna gain is found to be varying for such a study. It is found that the proposed antenna gain decays gradually, for example at 4.5, at which the gain is maximum, from 11.6 dBi to 2 dBi with increasing the resistance value as listed in Table 2. Such gain enhancement is achieved by cascading multi stages of MTM unit cells to realize a high gain at the resonant frequency. This observation is quite similar to the plasmonic resonance of the inherent resonant of the scatter structure [5]. This is due to the fact of affecting the resistance variation on the surface current motion [5]. Consequently, the values of BER are calculated according to the antenna gain at each LDR value. In such a process, the evaluated BER from R2022a MATLAB version 9.12 platform is performed by a computer simulation and numerical analysis QAM modulation scheme. The evaluated BER using a function returns a number in Matlab. The number of bits differ in the comparison and the ratio of number to the total number of bits. The function determines the order in which it compares transmitted bits to received bits based on their sizes.  
Figure 6: Antenna performance with different switching sceneries: (**a**) S\({}_{11}\) spectra and (**b**) gain.  
The simulation is conducted by considering AGWN channel for (8, 16, 32, and 64)-QAMs. The considered AGWN is channel is generated from a random source in a MATLAB function. The maximum bit error is placed at 100 and the maximum number of bits is taken as \(1\times 10^{7}\). The objective is to evaluate each QAM index with respect to BER against LDR resistance variation as listed in Table 2. It can be observed from the achieved results that BER decreases with the LDR value increase to perform better modulation in terms of BER with QAM order decrease.