Pulse propagation on a semiinfinite horizontal wire above ground: Near‐zone fields

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Abstract
The near zone electric field distribution due to a transient current pulse propagating on a semiinfinite wire above the ground is investigated. A quasi‐transverse electromagnetic approximation to the modal equation for the propagation wave number is used to obtain the time history of the pulse on the wire. Spectral domain techniques are then used to obtain an expression for the electric field. In the resulting two‐dimensional Sommerfeld integrals, representation of the angular integral in terms of incomplete Lipschitz‐Hankel integrals allows for the efficient computation of the frequency domain near and intermediate zone fields. A numerical inverse Fourier transform is then applied to obtain the transient response. Numerical results, presented in both the time and frequency domains, are used to determine when the previously obtained far zone approximations can be applied. The results in this paper are for the quasi‐transverse electromagnetic component of current; however, similar techniques can be applied to the Earth‐attached and continuous modes.