## 3 Simulation Results and Discussion
### Linearly Polarized MIMO RDRA (Design-1)  
The preliminary prototype was intended and evaluated utilizing the DWM model [13]. Through putting the DRA MIMO antenna on a base plane, similar modes were short-circuited, and just odd modes might be present [14]. Since this, odd modes, i.e., TE modes were energized. In corresponding, the operating frequency of the primary sort, \(TE_{513}^{x}\), \(\ast\) was calculated employing equations [15] where \(k_{x}\), \(k_{y}\), and \(k_{z}\) respectively represent the wave numbers in the \(x\), \(y\), and \(z\) routes within the DRA, as indicated in Equation (1):  
\[f_{0}=\frac{c}{2\pi\sqrt{e}r}\sqrt{k_{x}^{2}+k_{y}^{2}+k_{z}^{2}} \tag{1}\]  
\[k_{x}=\frac{\pi}{c} \tag{2}\]  
\[k_{z}=\frac{\pi}{2H} \tag{3}\]  
Likewise, the AR was characterized by:  
\[\frac{E_{y}}{E_{x}}=\frac{\left|E_{y}\right|}{\left|E_{x}\right|}\;\ast\;e^{i \Phi} \tag{4}\]  
Figure 2: Development of the RDRA MIMO Antenna (3D view): (**a**) Design-1: MIMO RDRA with a single strip; (**b**) Design-2: MIMO RDRA with a novel conformal metal strip; (**c**) desired MIMO RDRA. The electrical field ground vector's y-directed element was _Ey_, even though the x-guided component was _Ex_. For the difference in phase among _Ex_ and _Ey_, the breadth ratio was 1, and the phase variation (\(\phi\)) was 90\({}^{\circ}\) meant for the pure cp specification performance. The individual strip RDRA (Figure 2a) could have achieved a broader S\({}_{11}\) bandwidth, but it figure out do not get a axial ratio mode. Table 2 shows the optimal parameters for the RDRA's single copper metal feeds, established on meticulous parametric evaluation using the CST. This showed the impedance-matching bandwidth, which was susceptible to feed height, as altering it could degrade the results. After running the parametric sweep, the strip dimensions were optimized, and the optimal measurements of the particular strips were Sw = 11.75 mm and Sw = 1 mm. S11 bandwidths of \(\sim\)7.19% were achieved with the optimized feed parameters. Adjusting the feed's position could manage and optimize the RDRA's impedance-matching bandwidth (S11) [16]. As a result, parametric research was carried out for various d1 values. The best value of the d1 from the edge is shown in Figure 2a, whereas Figure 3 illustrates the numerous return-loss qualities of the RDRA with various values of d1: 7.50 mm, 8.00 mm, and 8.50 mm as of the side. Every estimate of d1 yielded a various return-loss estimate. The resonant frequency rose (higher frequencies) when the value changed, and the greatest reflection coefficient was attained when the gap was kept at d1 = 8 mm. \begin{table}
\begin{tabular}{|c|c|c|} \hline
**S1** & **Sw** & **10-dB S11 Bandwidth (\%)** \\ \hline  & 0.5 & 5.43 \\ \cline{2-3}  & & 5.18 \\ \cline{2-3}  & & 5.92 \\ \cline{2-3}  & & 4.65 \\ \cline{2-3}  & & 4.92 \\ \cline{2-3}
10.75 & & 5.17 \\ \cline{2-3}  & & 5.42 \\ \cline{2-3}  & & 5.96 \\ \cline{2-3}  & & 6.23 \\ \cline{2-3}  & & 6.58 \\ \hline  & & 6.89 \\ \cline{2-3}  & & 7.19 \\ \cline{2-3}
11.75 & 1 & 7.01 \\ \cline{2-3}  & & 6.75 \\ \cline{2-3}  & & 6.51 \\ \cline{2-3}  & & 4.90 \\ \hline  & & 4.42 \\ \cline{2-3}  & & 4.20 \\ \cline{2-3}  & 1.75 & 3.97 \\ \cline{2-3}
12.75 & & 3.75 \\ \cline{2-3}  & & 3.54 \\ \cline{2-3}  & & 3.34 \\ \cline{2-3}  & 2 & 5.91 \\ \hline \end{tabular}
\end{table} 
Table 2: Optimisation of the single-strip measurements in mm. Thus far away, the improved strips limitations and feed position had been confirmed. The individual metal strip of the DRA provided a computer-generated return-loss (S11) bandwidth of ~7.19%. A desired gain of ~5.2 dBi occurred through out the desired frequency range, as demonstrated in Figure 4; moreover, it is worth mentioning that Design-1 could not produce circularly polarized waves because ports 1 and 2 could excite only a single, higher-order mode \(TE_{\delta 13_{3}}^{x}\) inside the DR, whereas the generation of CP waves requires the exciting of two orthogonal-mode pairs, with a quadrature phase-shift between them [17].