RF coupling measurements on passenger aircraft avionics exposed to cavity-mode excitation

The performance of avionics installed in aircraft which fly through high-intensity electromagnetic environments is an increasingly important issue. The authors have completed the second phase of testing of the electromagnetic reverberation characteristics of a transport aircraft. A part of this testing was the measurement of the coupling of radio-frequency (RF) energy to selected avionics boxes of a decommissioned Boeing 707 aircraft and a simulated avionics box when exposed to cavity-mode excitation, The aircraft avionics boxes were instrumented to measure the RF energy coupling to: (1) an interior component lead and (2) an interior wire leading to the aircraft wiring harness connector plug. The simulated box was instrumented to measure RF coupling to an interior component lead. Tests, conducted on a 707, included excitation of the aircraft within the avionics bay, cockpit and passenger cabin, utilizing mode-stirring techniques. Follow-on tests were and continue to be performed in the Mode-Stirred Chamber (MSC). The aircraft and MSC tests are intended to demonstrate that the RF coupling characteristics of the actual and simulated avionics boxes measured within the MSC constitute valid descriptions of the RF coupling characteristics of the same boxes when installed in the aircraft. Data obtained on one of the avionics boxes during testing on the aircraft and in the will be presented.