Application of Radar-Absorbing Materials for Attenuating High-Frequency Interference in the Electrical Circuits of Aircraft Electrical Systems

Abstract

Conducted high-frequency electromagnetic interference is induced in the electrical circuits of aircraft electrical systems under the effect of external man-induced electromagnetic fields penetrating into the aircraft structure through radio-transparent apertures. To attenuate the impact of the conducted high-frequency electromagnetic interference induced in the two-wire lines of electrical bundles and other electrical circuits of electrical systems on sensitive semiconductor elements and integral microchips of on-board instruments and devices, low-pass filers on the basis of lumped components are used. At high frequencies, resonance phenomena may occur in the filter electrical circuits, which degrade the filter capabilities to attenuate conducted interference. Conducted high-frequency interference can be attenuated, and their propagation paths in the two-wire lines of electrical bundles and in the electrical circuits of on-board instruments and electrical system devices can be eliminated by applying radar-absorbing materials (RAM). Conducted electromagnetic interference in two-wire lines at a frequency above 1000 MHz generates high-frequency electromagnetic fields. With RAM placed in close proximity to the conductors of two-wire lines, it is possible to attenuate conducted high-frequency interference due to absorption of the interference electromagnetic field energy. The results of experimental studies are presented, the data of which make it possible to evaluate the extent to which the conducted high-frequency interference is attenuated in the frequency band 0.1–3000 MHz by applying radar-absorbing materials.