## 3 A320 Cabin Interference Path Loss Simulation
### Simulation Results and Analysis  
The aircraft cabin has a total of 40 rows of windows. A dipole antenna is placed at each window position in the cabin, and the \(S_{21}\) parameter is calculated for each location. According to Equation (2), \(S_{21}\) represents the IPL value. For each window position, the dipole antenna sweeps the frequency range and the IPL value is determined. Since the mobile phone supports the Tiantong satellite communication system, which operates in the 1980-2010 MHz and 2170-2200 MHz frequency bands, this study presents simulated IPL values between the GPS antenna and a high power PED in the 1500-1600 MHz and 1980-2200 MHz bands. During the simulation, 1000 sample points are collected within each frequency range. Various factors, including the PED position within the same row of windows, positions across different rows, different frequency bands, and antenna polarization methods, are analyzed to assess their impact on the IPL. The results are shown in Figure 4.  
To avoid presenting an excessive amount of simulation data, this paper shows only a selection of results to analyze the variation tendency of IPL values. The analysis focuses on the maximum, minimum and average IPL values under various influencing factors, and calculates the standard deviation (SD), and 95% confidence interval (CI). A statistical analysis of the results is provided in Table 2.  
The confidence interval shown in Table 2 indicates a 95% probability that the average IPL value falls within this range. When the PED is positioned at different locations (left, center and right) within the same row of windows, the IPL values are 71.36 \(\pm\) 0.32, 71.81 \(\pm\) 0.35, and 71.60 \(\pm\) 0.33 dB, respectively. A significance test was performed on the simulation results for the different conditions listed in the table. The results indicate that  
Figure 4: Simulated analysis of factors influencing IPL: (**a**) PED at the left, center and right side of the 4 th row of windows. (**b**) PED at the 4 th and 40 th row of windows. (**c**) PED at different frequency bands. (**d**) PED at the 4 th row of windows with different polarization methods.  
there is no significant difference when the PED is located at the left, center, or right side of the windows. Therefore, only the case with the PED placed on the right side of the cabin is considered in subsequent simulations. When the PED is moved to the 40 th row of windows, the average IPL value increases to 75.86 \(\pm\) 0.32 dB, which is 4.26 dB higher than at the 4 th row. This increase is primarily due to the GPS antenna's location, and as the distance inside the cabin increases, the IPL value rises.  
Each dipole antenna was vertically polarized in the above research. When the polarization of the dipole antenna inside the cabin is changed, while keeping the frequency band at 1500-1600 MHz, the average IPL increases to 74.25 \(\pm\) 0.33 dB, which is 2.44 dB higher than the value for vertical polarization at the same location. This increase is likely because the vertical polarization aligns with the cabin doors and other apertures, enhancing the electromagnetic coupling. As a result, more energy is received by the external antenna, reducing the average IPL value. When the dipole antenna is set to vertical polarization and the frequency band is changed from 1500 to 1600 MHz to the satellite communication band of 1980-2200 MHz, the average IPL rises to 79.88 \(\pm\) 0.35 dB, which is 8.28 dB higher than in the 1500-1600 MHz band. This indicates that increasing the frequency significantly increases the IPL value.  
Except for the comparison of PED placement at different positions within the same row of windows, all other comparisons showed significant differences according to the significance test. This indicates that the trends observed in the simulation are reliable. To further validate the simulation results, field measurement experiments are conducted in the next chapter.