Study On High-intensity Radiation Fields Test Method And Protection Technology Of Airborne Equipment

With the modern military and civilian electronic equipment are widely used,including navigation,radar,communication,electromagnetic jammer and so on.It was resulted electromagnetic signals in the combat environment formed a very complex electromagnetic environment.High-intensity radiated fields(HIRF)are an important part of complex electromagnetic environments,mainly from the energy emitted by radar,radio,radio transmitters and other ground-based,ship-borne or airborne RF transmitters.HIRF as an electromagnetic interference source may enter the aircraft’s internal compartments through the coupling path of doors and windows,antennas,holes and other path.The induction current on the electromagnetic field or cable bundle coupled into the compartment may cause radiation interference or conduction interference of the airborne equipment,which in severe cases will affect the normal work of the airborne equipment.Therefore,it is of great practical engineering significance to carry out the HIRF test method and protection of airborne equipment.First of all,this paper referred to the DO 160-G standard in the frequency band of 400 MHz to 2 GHz,a helicopter airborne radio was used as a test subject in the reverberation chamber HIRF sensitivity test system,took as the test object,the typical fault type and sensitivity threshold of the test equipment were respectively determined in different working modes of the reverberation chamber by changing the electric field strength.The results show that the sensitivity threshold of the airborne radio station can be measured more easily in agitator continuous mode than step-by-step operation mode under the same conditions as the test environment field.In continuous working mode,the sensitivity threshold of the airborne radio station was tested decreases with the faster stirring speed and the tested results of sensitivity threshold decreased with the increase of pulse width.Secondly,according to the mechanism of HIRF coupling,the paper simulated and analyzed the influence regularity of seam coupling and cable coupling about the shielding case of airborne equipment through CST simulation software.The simulation results show that: In the design of the shielding case of the airborne equipment,we should try to avoid the direction of electric field polarization and the long edge vertical of the hole seam;Low-frequency sensitive equipment inside the shield case should be installed as far away from the hole seam position as far as possible,and the position of the sensitive equipment inside the cavity and the center of the hole seam should be kept in a straight line;In the shape of the hole seam as far as possible to choose the round hole and square hole,if the use of rectangular hole,should be reduced as much as possible the length and width ratio;For the same hole seam area,more than one hole seam should be selected instead of a hole seam;Relative to single wire,twisted pair and coaxial line,the internal cable of the on-board equipment shielding box should be preferred to select the same-axis cable with shielding effect better.Finally,the paper according to the mechanism of HIRF coupling and simulation results,combined with electromagnetic compatibility commonly used shielding,filtering,grounding and other measures,provided several optimization schemes for the airborne equipment HIRF protection.This paper can provide reference for perfecting the test methods and standard specifications for the performance of electromagnetic radiation protection about airborne equipment,and the construction of the conditions for the adaptive testing of complex electromagnetic environment carried out by military research units.