Effect of initial accumulated charge on electromagnetic radiation of ESD

Electromagnetic pulse radiation generated by Electrostatic discharge (ESD) would damage even destroy the normal work of the electronic system. It was usually not considering the impact of the initial accumulated charge in previous studies of ESD electromagnetic radiation. In this paper, on the basis of taking into account the cumulative effect of the initial charge, the electromagnetic radiation of ESD has been analyzed on different distance and the threshold of "near-field" and "far-field" has been calculated on different discharge voltage. The results show that under a certain discharge voltage, the electric field generated by current and current differential item is negligible compared to the accumulation of the initial charge on the electrode, which has a great influence on the "near-field". The initial accumulated charge on the role of the electric field decline rapidly with the increase in distance between the electric field point and the discharge point. The threshold of "near-field" and far-field" increased along with the discharge voltage.