Cavity to cavity coupling measurements in commercial aircraft and the implications for on-board operation of personal electronic devices

Characterization of the cavity electromagnetic environment and various coupling mechanisms to aircraft systems have been performed for internal emitters. One potential coupling mechanism is radiative coupling to wire bundles which then penetrate an electronic system enclosure as well as direct aperture coupling to the enclosure. This paper addresses the issue of cavity-to-cavity coupling or the electromagnetic environment in one cavity due to an emitter in another cavity. Cavity-to-cavity coupling needs to be considered since commercial aircraft design does not specifically provide for significant cavity isolation. The paper presents cavity-to cavity coupling data for two narrow body aircraft. The experimental approach and the resulting data are applicable to frequency regions where the cavities are multi-moded. Coupling data are provided from the passenger cabin to cockpit and avionics bay. An application of this information is to quantify the potential for electromagnetic interference from portable electronic devices which may be operated in the passenger cabin. Based on the measured cavity electromagnetic environment data, the paper provides a preliminary estimate of the relationships between the number and power output of portable electronic devices in the passenger cabin and the radiative environment levels expected in the cockpit or avionics bay.