## 3 Results and Discussions  
At first, the reflection coefficient of the proposed antenna was investigated and experimentally verified for an antenna without solar panels and with solar panel integration, as shown in Figure 2. It is shown in Figure 2 that the antenna operated at 420.5 MHz with \(-\)20.95 dB reflection coefficient before solar panel integration. The measured result showed \(-\)18.12 dB reflection coefficient at 419.8 MHz. The simulated and measured reflection bandwidths were 2.30 MHz (419.2-421.5 MHz) and 3.3 MHz (418.2-421.5 MHz), respectively. Both results were in good agreement. However, a little mismatch occurred due to fabrication tolerance. After that, the reflection coefficient was investigated with solar panel integration. Then the operating frequency shifted to 400.75 MHz due to the lossy material properties of the solar panel. The simulated and measured bandwidths were found to be 3.4 MHz (399.10-402.5 MHz) and 3.3 MHz (399.2-402.5 MHz), respectively. The surface current distribution of the proposed antenna with and without solar panel integration was analyzed to understand the effective electrical length of the antenna. From Figure 3a, it is seen that the maximum current was observed near the shorting wall and the current flowed towards the elliptical slots. Moreover, some strong current was also observed at circular slots of the radiating patch. Therefore, a larger electric path was formed to miniaturize the antenna structure, and about 60% of the surface was truncated for solar irradiance. Figure 3b also shows a similar pattern after solar panel integration. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameters** & **Value (mm)** & **Parameters** & **Value (mm)** \\ \hline L & 100 & L\({}_{4}\) & 8.5 \\ W & 100 & L\({}_{5}\) & 8.5 \\ h & 5 & a\({}_{1}\) & 36 \\ L\({}_{1}\) & 86 & a\({}_{2}\) & 40 \\ L\({}_{2}\) & 78 & b\({}_{1}\) & 10 \\ L\({}_{3}\) & 24 & b\({}_{2}\) & 7 \\ r\({}_{1}\) & 4 & r\({}_{2}\) & 1.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Design parameters of the proposed antenna. Figure 2: Reflection coefficient of the proposed antenna. The radiation pattern of the proposed antenna was analyzed with 1U nanosatellite structure. Both 3D and the 2D radiation patterns are presented in Figure 4a,b. The antenna achieved 0.672 dB of realized gain at the 401 MHz frequency band, as seen in Figure 4a. Figure 4b shows that the antenna achieved a nearly omnidirectional radiation pattern in the azimuth plane. The radiation characteristics of the antennas were measured in Satimo's Star Lab near the field antenna measurement system at Laird Technologies (M) Sdn Bhd, Malaysia, as shown in Figure 4c. The simulation and measured radiation patterns showed a little discrepancy. This discrepancy arose out of the fact that the nanosatellite model used in the simulation and the fabricated model used in measurement were not exactly equivalent, due to differences in material properties of the nanosatellite structure. The antenna showed 70.88% of total efficiency and 0.672 dB realized gain with 1U nanosatellite structure, as shown in Figure 5.  
Figure 4: \(Cont\). Figure 3: Surface current distribution of the proposed antenna—(**a**) only antenna and (**b**) antenna with solar panel. Figure 4: Antenna radiation pattern with satellite structure—(**a**) simulated 3D radiation pattern, (**b**) 2D radiation pattern (**c**) measurement setup and (**d**) measured radiation pattern. Figure 5: Antenna radiation efficiency and gain pattern with satellite structure. The solar panel output power with and without antenna integration was also investigated, shown in Figure 6. Solar simulator SML-2K1 MV1 and pyranometer MS-802 were used in this measurement. Initially, the solar panels were placed satellite backplane board and output power was measured. Then, the antenna was placed upon the solar panel and solar panel output power was measured.