Research On Environment Of Electromagnetic Pulse In Sea Environment

The electromagnetic environment faced by modern ships is becoming more and more congested.It's highly significant for the safety of ship-based electronic information systems to predict and describe the electromagnetic pulse environment in both time-domain and frequency-domain and to ascertain waveform characteristics of electromagnetic pulses received by the sensitive device in a situation where the electromagnetic pulse is scattered by the rough sea surface.Firstly,the geometrical and electromagnetic model of the compound objective composed of ship and sea surface is built.To research factors influencing on the transient electromagnetic environment of ships under sea background,simulation is done when sea conditions,the electromagnetic wave's grazing angle and frequency change.Meanwhile,in view of the harm received by fuel oil and electronic devices while electromagnetic wave with high energy radiating at a ship,the harm areas caused by electromagnetic radiation are predicted to eliminate the harm.Secondly,the parameters and standards of waveform of some typical time-domain electromagnetic pulses are consulted,and the typical waveform of electromagnetic pulses is selected to simulate the electromagnetic environment.On account of the difficulty while simulating and measuring the time-domain environment of electromagnetic pulses where electrically large objectives exist,a technology is proposed to obtain electromagnetic pulse waveform in time-domain by inverting the amplitude response in frequency-domain.In addition,the application condition of this reconstitution algorithm is analyzed.Thirdly,in view of limitation during inverting the amplitude response in frequency-domain,a reconstitution algorithm based on ray-tracing method is proposed to solve reconstitution problems under unsuitable conditions.Based on the transmitting mechanism of rays round complex objectives,with a scene model of ray-tracing established in the sea condition,information about ray paths is extracted and electric field is calculated.In the end,the pulse waveform at observation points around sensitive devices is obtained by inverse Fourier transformation using electric field of all the frequencies.