Propagation of the transient electromagnetic field above atmospheric surface duct

摘要

The transient electromagnetic field generated by a vertical magnetic dipole above an evaporation duct is investigated theoretically. The source of the electromagnetic field is taken to be a vertical magnetic dipole above an evaporation duct with arbitrary time varying moment. The application of two integral transform to the wave equation for the Fitzgerald vector––a Laplace transform in time and a two-dimensional Fourier transform in the horizontal coordinates in space-leads, under consideration of initial boundary and transition condition. The modified Cagniard method is used to derive closed form expressions for Fitzgerald vector anywhere above the duct and based on evaluating the field in a series of image sources of the primary source. Hence we can give a physically intuitive description of the polarization dependence of the time.