In this paper, three methods for calculating electromagnetic fields radiated from complex lightning channels are discussed, which includes channel obliqueness, branches and tortuosity. By rotating and moving the coordinate system of the vertical channel, differential expressions of electromagnetic fields from the irregular channel can be derived from the conclusions of the straight and vertical channel. Through analyzing calculation results of two examples reveals that channel tortuosity and branch is to introduce the higher frequency content above 100 kHz into lightning electromagnetic fields.
2. Uman, M. A., "Natural lightning," IEEE Transactions on Industry Applications, Vol. 30, No. 3, 785-790, 1994.
3. Song, T.-X. and C.Wang, "Two numerical methods for calculating electromagnetic fields radiated from nature lightning," Journal of Electromagnetic Waves and Applications, Vol. 19, No. 4, 513-528, 2005.
4. Nucci, C. A., et al., "Lightning return stroke current models with specified channel-base current: a review and comparison," J. Geophys. Res., Vol. 95, 20395-20408, 1990.
5. Rakov, V. A. and M. A. Uman, "Review and evaluation of lightning return stroke models including some aspects of their application," IEEE Transactions on Electromagnetic Compatibility, Vol. 40, No. 4, 403-426, 1998.
6. Zhao, X. and K. Huang, "Calculation of probability distribution of Maximal received power of electronic receiver in lightning electromagnetic environment," Journal of Electromagnetic Waves and Applications, Vol. 19, No. 2, 221-230, 2005.
7. Mu, M. K., J. T. Huangfu, L. X. Ran, and K. Zang, "Design of lightning protector compatible for both 2G and 3G cellular systems," Journal of Electromagnetic Waves and Applications, Vol. 20, No. 15, 2167-2175, 2006.
8. Li, J. Y. and Y.-B. Gan, "Multi-band characteristic of open sleeve antenna," Progress In Electromagnetics Research, Vol. 58, 135-148, 2006.
9. Sijher, T. S. and A. A. Kishk, "Antenna modeling by infinitesimal dipoles using genetic algorithms," Progress In Electromagnetics Research, Vol. 52, 225-254, 2005.