When a lightning strikes a high object, the current flows along the object and produces in this way a field component additional to the field radiated from the lightning channel. This additional field component enhances the field compared to lightning to flat ground. In this article, the field enhancement is analyzed for lightning striking the Peissenberg Tower, Germany. The analysis is based on investigations of the far field at distances from 10 to 1000 km. In the computer simulations, the return stroke process is taken into account with the transmission line (TL)-model and the tower is modelled with the computer program CONCEPT II based on the method of moments. In a first step, the pure effect of the tower is analyzed. In this case, the ground is taken into account as perfectly conducting plane. In the next step, the effect of the field propagation is added by introducing an attenuation function based on the solution of Sommerfeld and a far-field approximation of Norton. For fast rising return stroke currents and relatively near distances between 10 and 30 km, the field enhancement may exceed 100%. The field enhancement decreases strongly with decreasing soil conductivity (σ) and increasing distance (s), while the influence of the permittivity (ε) is rather small. At a distance of more than 100 km the field enhancement is typically in the range of some tens of percent. This result agrees well with the data of the European lightning location system EUCLID. From EUCLID an average field enhancement of about 20% is reported for lightning striking the Peissenberg Tower.

中文翻译：

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雷击高塔与雷击平地的场增强


当闪电击中高处物体时，电流沿着该物体流动，并以这种方式产生除了从闪电通道辐射的场之外的场分量。与闪电到平坦地面相比，这个附加的场分量增强了场。在本文中，分析了雷击德国佩森伯格塔的场增强。该分析基于对 10 至 1000 公里远场的调查。在计算机模拟中，使用传输线（TL）模型考虑回程过程，并使用基于力矩方法的计算机程序CONCEPT II 对塔进行建模。第一步，分析塔的纯粹效果。在这种情况下，地面被视为完美的导电平面。在下一步中，通过引入基于索末菲解和诺顿远场近似的衰减函数来添加场传播的影响。对于快速上升的回程电流和 10 至 30 公里之间相对较近的距离，磁场增强可能超过 100%。随着土壤电导率（σ）的减小和距离（s）的增加，场增强强烈减弱，而介电常数（ε）的影响相当小。在超过 100 公里的距离处，场增强通常在百分之几十左右。这一结果与欧洲闪电定位系统EUCLID的数据非常吻合。据 EUCLID 报道，雷击佩森伯格塔的平均场增强约为 20%。