Calculation of Lightning Radiation Field Considering the Effect of Ionosphere

In this paper, the effect of ionosphere to the lightning radiation magnetic field is investigated using Sommerfeld integral. Supposing that the ionosphere is perfect conductor layer, the rigorous and simplified expressions of magnetic field are both obtained. Based on the engineering model, the obtained expression is applied to analyzing the characteristics of lightning radiation magnetic field. The analysis indicates that the reflection from the ionosphere results in multiple peaks in lightning radiation magnetic field. Accordingly, some of the subsequent peaks in the measurement of lightning radiation fields, usually taken as subsequent strokes, may result from the reflection of the ionosphere.