EVALUATION OF THE SHIELDING COEFFICIENT BY CRITICAL SYSTEM FUSELAGE IN THE COMPOSITION OF THE AIRCRAFT

Abstract

This article discusses the problems of ensuring the flight safety of aircraft using electrical /
electronic systems when exposed to high-intensity electromagnetic fields. A method is being developed
for analyzing the impact of high-intensity radiated fields that create an electromagnetic environment
in the aircraft location area, based on the main factors of the aircraft electromagnetic
compatibility, such as the electromagnetic environment, the mechanism of communication or action,
the sensitivity or susceptibility of electromagnetic radiation receivers with threshold values of
interference in the frequency and time domains. Two methods for assessing the aircraft resistance
to high-intensity electromagnetic fields are analyzed: high-level scan tests and low-level scan
tests. The purpose of this article is to estimate the fuselage shielding coefficient in the places
where critical systems units are installed using software for numerical electrodynamic modeling.
The objective of the study is to create and calculate a mathematical model of the critical system as
part of an aircraft. The article developed electrodynamic models of the critical system of the aircraft
– a multifunctional liquid crystal indicator, and the calculation is carried out in the Ansys
HFSS full-wave electrodynamic design package. Reasonable simplifications are made to the HFSS
cockpit model for calculating the fuselage-shielding factor. Simplifying the model means eliminating
small parts and objects that are much shorter than the wavelength and reducing the model's
area of study, since the critical system blocks are located in the front of the cockpit. The estimation
of the fuselage-shielding factor in the frequency range from 100 MHz to 1 GHz is carried out, the
analysis and comparison of the results obtained with the tests in the aircraft are carried out. The
results are of a similar nature, however, the calculated values of the shielding factor are 5–15 dB
lower in the frequency range from 400 to 850 MHz. Also in the frequency range up to 400 MHz,
there are characteristic resonant "dips" of the screening coefficient. The results obtained will
make it possible to single out the most dangerous sources and zones of excitation of electromagnetic
interference for subsequent detailed analysis, and to reduce the time and cost of testing.