A study of the HEMP environment over ship board based on signal reconstruction

To study the electromagnetic environment above the board of ship when high-altitude nuclear electromagnetic pulse (HEMP) radiated to it, a new method based on signal reconstruction is presented. By adopting FFT method, the HEMP signal is decomposed into a sum of sine continuous waves of different frequencies, and the amplitude response of the ship at each frequency, namely the amplitude spectrum can be obtained by simulation. As the HEMP signal meets the condition of minimum phase, the time-domain electromagnetic pulse signal can be reconstructed from the amplitude spectrum. Time-domain HEMP signals at three typical positions above board of ship were reconstructed, and electric field intensity distribution at three typical frequency was also presented. The result shows that mast has blocking effect towards electromagnetic wave, which is enhanced when the frequency increases from 100 MHz to 1 GHz. And the amplitude of constructed HEMP signal varies as the azimuth of radiation changes.