Graphical analysis of B-737 airplane pathloss data for GPS and evaluation of coupling mitigation techniques

The use of portable electronic devices (PEDs) onboard commercial airliners is considered to be desirable for many passengers. However, the possibility of electromagnetic interference (EMI) caused by these devices may affect flight safety. PEDs may act as transmitters, both intentional and unintentional, and their signals may be detected by the various navigation and communication radios onboard the aircraft. Interference pathloss (IPL) is defined as the measurement of the radiated field coupling between passenger cabin locations and aircraft communication and navigation receivers, via their antennas. The paper first focuses on IPL measurements for GPS, taken on an out-of-service United Airlines B-737-200. IPL pattern symmetry is verified by analyzing data obtained on the windows of both the port and starboard sides of the aircraft. Further graphical analysis is performed with the door and exit seams sealed with conductive tape in order to understand better the effects of shielding on IPL patterns. Shielding effects are analyzed from window data for VHF and LOC systems. In addition, the shielding benefit of applying electrically conductive film to aircraft windows is evaluated for GPS and TCAS systems.