## 5 Analysis of Front Door Coupling Interference  
The experimental results have confirmed the feasibility of using this model for simulation analysis. Building on the simulation results, this section explores the potential impact of front-door coupling interference. Front-door coupling of spurious radiated emissions (NIRA) refers to the spurious emissions from PEDs that are received by the aircraft's radio receiver antennas, potentially interfering with the aircraft's radio receivers. Front-door coupling of intentional radiated emissions (IRA) refers to the intentional emissions from PEDs occurring within licensed frequency bands (such as bands allocated to mobile phones). Considering both types of front-door coupling, if a PED can transmit a 2 W signal within the 1985-2005 MHz frequency range, the \(IPL_{target}\) can be calculated. The simulation results are then analyzed to evaluate the electromagnetic interference from the PED to the GPS antenna, comparing IPL with \(IPL_{target}\), as shown in Figure 12.  
It is crucial to hig light that all results in this study were derived under the worst-case scenario, where the spurious radiation limit was set at \(-40\) dBm. It is certain that the actual measured values will be lower than this threshold. The value of sp  
Figure 11: Difference in average IPL value between simulation and measurement.  
Figure 12: Comparison of IPL and \(IPL_{target}\): (**a**) NIRA. (**b**) IRA.  
the determination of the \(IPL_{target}\). If the spurious emission level is lower than \(-40\) dBm, the corresponding \(IPL_{target}\) for the NIRA will decrease proportionally.  
A comparison of the \(IPL_{target}\) with the simulated IPL values reveals that for NIRA, the IPL does not meet the required interference path loss target at specific frequencies. This indicates that the energy received by the GPS antenna surpasses the interference threshold. For these frequencies, considering the difference of IPL between simulation and measurement, the maximum difference between the IPL and \(IPL_{target}\) is approximately \(15\pm 3\) dB. A study [10] suggests that when the IPL exceeds the \(IPL_{target}\) by less than 10 dB, the likelihood of interference is minimal and can be considered negligible. However, the results shown in NIRA should be interpreted with caution. In the case of IRA, the IPL far exceeds the \(IPL_{target}\) by around 70 dB, suggesting that the intentional emissions from the PED are unlikely to cause interference with the GPS antenna.  
All data on GPS interference thresholds are derived from the guidelines in Appendix B, Volume I of ICAO Annex 10 [24]. In the worst-case scenario, spurious emissions reach \(-40\) dBm in the GPS L1 band. We observed a difference of 2.997 \(\pm\) 0.678 dB between the simulated and measured average IPL values. Therefore, a conservative estimate suggests that the spurious emission power of mobile phones must be below \(-60\) dBm in the GPS L1 band when using the satellite communication function to effectively reduce the risk of interference.  
In conclusion, during critical flight phases, strict regulation of passengers' use of satellite communication functions is crucial to prevent interference with the aircraft's navigation systems. In addition to restricting its use, improving the IPL value is vital for minimizing its impact. Research indicates that designing aircraft windows with varying structures and materials can help mitigate the impact of internal electronic devices on antennas [30]. These approaches can be integrated into electromagnetic shielding designs to address more complex operational scenarios.