Effect of different lightning shapes on electromagnetic spectrum characteristics

To study the effect of natural lightning shapes on electromagnetic spectrum characteristics, a new method leading to the law of lightning electromagnetic spectrum characteristics is put forward. Firstly, generate 3-D lightning channel models randomly with different shapes by setting different parameters of dielectric breakdown model. Then, add excitation, namely double-exponential lightning current. Lastly, calculate the characteristics of time-varying electric field spectrum using finite difference time domain (FDTD) method. Research shows that fractal dimension has great influence on spectrum characteristics of lightning leader. The degree of influences of probability exponent on the lightning spectrum characteristics is more than that of internal electric field of the channel while critical electric field threshold is the least. Results show that there is an obviously linear correlation between probability exponent and lightning spectrum peak value. Some useful conclusions have been drawn from the research, which will be reference for lightning simulation, especially for the spectrum research.