EMC-based skin-effect grounding for reliable lightning protection system of antenna system

摘要

From EMC point of view lightning can be considered as the most destructive interference source for any sensitive electronic equipment. Its high impulse current conducted upon antenna's cable armor could generate magnetic field, which induces dangerous overvoltage or current within equipment circuits. Such magnetic induction gives some adverse effects to the equipment, such as improper function or even destruction, leading to system's shutdown. This adverse phenomenon occurs frequently as lightning strikes the antenna's communication although the tower is already protected with standard lightning protection system. This paper proposed a novel grounding method, so-called skin effect grounding, for reducing high impulse current of lightning possibly coming into radio room through antenna's coaxial cable. The proposed method is working based upon skin effect principle, in which high frequency characteristic of impulse high current of lightning is considerably taken into account for more effective galvanic interference decoupling. The proposed method allows the reduction of impulse high current of lightning coming into radio room to the acceptable level below system immunity so that magnetic field generated can be considered as not harmful for the system. For years the proposed method has been implemented and well proved within the lightning protection system of communication center of oil & gas industries as well as telecommunication companies.