Evaluation of the transient electromagnetic field in evaporation duct

摘要

The pulsed electromagnetic radiation from a vertical magnetic dipole in evaporation duct is investigated theoretically. The electric and magnetic fields are then derived from the Hertz vector by using the Sommerfeld integral. The integral is estimated by using the steepest descent method, and at last we obtain the electric and magnetic fields in the ionosphere. From the obtained results, the saddle-point method shows that the reflected waves, and integrals along the branch cuts undergo lateral wave. Physical meaning and numerical calculations are given for the φ-component of the magnetic field and graphically represented.