## 5 E-Field Distributions Because of Parasitic Patch  
By assessing the electric field distribution inside the geometry of RDRA using Eigen mode analysis, the parasitic patch feed of RDRA is used to stimulate the orthogonal fields in the suggested RDRA, as shown in Figure 8. The performance of circular polarization is defined by the drive of the electric field within the RDRA at four (4) different phases (t), namely 0\({}^{\circ}\), 90\({}^{\circ}\), 180\({}^{\circ}\), and 270\({}^{\circ}\). The direction of the electric field varies according to phases if the phase angle fluctuates 90\({}^{\circ}\) or 180\({}^{\circ}\) to 270\({}^{\circ}\), as seen in Figure 7. When the phase shifts from 0\({}^{\circ}\) to 180\({}^{\circ}\), the electric field spins in the opposite direction in parallel. Similarly, when the phase changes from 90\({}^{\circ}\) to 270\({}^{\circ}\), similar performance is seen. Thus, the given parameters confirmed that the parasitic patch on top is likewise responsible for the creation of CP radiation in the suggested RDRA.  
In order to check whether the proposed design excites right-handed circular polarization (RHCP)/left-handed circular polarization (LHCP) or both, again the simulated E-field distributions will be considered. The upper surface of the proposed RDRA is depicted in Figure 9a,b at 3.47 and 4.41 GHz respectively. The different polarity of the radiated CP wave is determined by the rotation of the E-field vectors. Comparing from t = 0 to t = T, the vector of major E-fields at t = T/4 is orthogonal to that at t = 0 and rotates counterclockwise as the time increases, therefore at band 3.47 GHz, producing RHCP fields as shown in Figure 8a.  
Similarly, as depicted in Figure 8b 4.41 GHz, clockwise rotation is produced, and an LHCP is generated. Therefore, RHCP and LHCP can be achieved respectively at the two bands, and the dual-band CP antenna is produced. As shown in Table 3, the outcome of the proposed RDRA is relatively better than single and cross-shape feed antennas. It features impedance bandwidths of 6.4% (3.47-3.61 GHz) and 25.26% (4.0-4.90 GHz), and 3-dB AR bandwidths of 12.6% (3.40-3.80 GHz) and 27.82% (4.03-4.97 GHz) in the lower and upper bands, respectively.  
Figure 7: Simulated S-parameter and Axial ratio of the proposed RDRA.  
Finally, Table 4 tabulates an evaluation of the anticipated RDRA and other formerly claimed dual-CP antennas in the literature. Dual-band and dual-CP antennas have been tabulated in the table below, but mostly have complex structures and complicated techniques to generate CP waves. The proposed antenna offers a solution to the problem. The suggested antenna has the largest AR bandwidth, this distinguishes it from previous dual-band dual-CP systems. Furthermore, the recommended DRA offers an enhanced and flat gain, outperforming previous research. Furthermore, unlike [5, 9], the suggested DRA has a simpler architecture with no intricate feeding networks or bulky elements.  
Figure 8: Electric field distribution inside the proposed design (**a**), Phase 00, (**b**), Phase 90\({}^{\circ}\) (**c**), Phase 180\({}^{\circ}\) (**d**) Phase 270\({}^{\circ}\)(by using Eigen mode analysis in CST-MWS).  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Antenna (RDRA)** & \begin{tabular}{c} **Lower-Band** \\ **BW** \\ **(1S\({}_{11}\) \(<\) \(-\)10 dB)** \\ \end{tabular} & \begin{tabular}{c} **Upper-Band** \\ **BW** \\ **(1S\({}_{11}\) \(|\)\(<\) \(-\)10 dB)** \\ \end{tabular} & \
\begin{tabular}{c} **Lower-Band** \\ **3-dB ARBW** \\ \end{tabular} &
\begin{tabular}{c} **Upper-Band** \\ **3-dB ARBW** \\ \end{tabular} \\ \hline Single feed & 7.99\% & 0 & 0 & 0 \\ \hline Cross-shape feed & 5.2\% & 19.2\% & 12\% & 24.63\% \\ \hline Proposed RDRA & 6.4\% & 25.26\% & 12.6\% & 27.82\% \\ \hline \hline \end{tabular}
\end{table}
Table 3: Performance of all antennas (frequency unit: GHz).  
Figure 9: Simulated E-field distributions on the top view of proposed RDRA at various times. (**a**) RHCP at 3.47 GHz. (**b**) LHCP at 4.41 GHz.