External Interaction of High Frequency Electromagnetic Waves with a Boeing 707 Fuselage

In the last decade, high intensity RF (HERF) sources are rapidly increasing, both in power and in number. Among them are the high power shortwave broadcast stations, operating in the HF band. New generation "fly-by-wire" aircraft, with their susceptibility to HIRF, on the one hand, and the criticality of the avionics, on the other, have been a source of concern to aircraft designers and users. Any external electromagnetic waves coupling to avionics begins with the interaction of the external incident electromagnetic waves with the "victim" aircraft fuselage. The problem of external coupling of electromagnetic waves to the metal structure of an aircraft is discussed in this paper. Theoretical data is presented, and a comparison between results of coupling analysis, using various analytical methods, including Method of Moments (M-O-M) are presented. Previous papers discussed the coupling to small aircraft [13] where the resonant frequencies correlate to the actual dimensions of the aircraft, and those typically lied within the HF band. In this paper, the coupling to a much larger aircraft structure, with the peculiar problems associated with it, for instance - secondary resonances which correlate to the dimensions of the aircraft.