Investigation on the Influence of Balun to the Lightning Electromagnetic Coupling Effects of Planar Dipole Working at 890-954 MHz

In this article, the influence of balun on the lighting electromagnetic coupling effects of planar dipole working at 890-954 MHz is investigated. The planar dipole is placed near the lightning channel. Based on the electromagnetic model of the lightning return stroke, the following two aspects are researched: first, the influence of the position of balun-cable to the lightning coupling effects, including the influence of the first return stroke and subsequent return stroke to the coupling effects of the planar dipole. Second, the influence of the distance between balun and coaxial cable to coupling effects of antenna. It can be found that the position of the balun-cable has great impacts on the lightning coupling effects of the planar dipole, even exceeding the impacts caused by the polarization of the antenna, which is installed on the communication tower and located near the lightning channel. Meanwhile, although the energy of the first return stroke is much greater than that of the subsequent return stroke, the energy of the subsequent return stroke coupling into the planar dipole is greater than that of the first return stroke. It is also found that the coupling effect of the antenna is approximately proportional to thedistance between the balun and the coaxial cable at the same height above the ground.