الفهرس 
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Abstract
The problem of. evaluating the induced transient current on any arbitrary point on an infinite horizontal perfectly nductingthin wire parallel to an infinite ground plane
e to a transient excitation of a linear antenna is care¬1y analysed in this thesis.
The problem of evaluating the steady state current on
e wire due to a short dipole with any orientation is reported in literature. The induced current due to a transient signal on any antenna has met any attention by other authors.
The thesis consists of seven chapters. Chapter (I) is the propagating fields o.f a dipole source a conducting ground. Expressions for
e Hertzian vector potentials in both the air and the earth are derived. In the air region the field is given by of the primary field emitted directly from the
the reflected field from the interface. In the region the field is represented by the transmitted through the interface only. Expressions of the Hertz¬$Zl vector potentials in both regions include Sommerfeld ntegrals which are evaluated asymptotically using the teepest descent method techniques. In regions away from
i.e large elevation angles, the field is
be space wave while near the interface it
as the ground wave.
Chapter (II) deals with an infinitely long thin wire ced horizontally above an air-earth interface. An roximate expression for the modal characteristic equa¬on of this structure is derived when the wire is excited a specified source. The solutions of the modal equation the possible propagating modes over the wire. propagating mode is the transmission-line mode. is characterized by a phase velocity that is less than of light in free space. The second mode is the mode. It is characterized by a phase velocity than the speed of light in free space. At the end chapter the current induced on the wire is also
In chapter (Ill) we consider a system formed by a oriented dipole source and an infinitely long placed horizontally over an air-earth interface.
e dipole source has three orientations, the vertical dipole VED , the horizontal electric dipole
to the wire axis HEDP and the horizontal electric wire axis HEDN. Exprebsions for the horizontal wire are derived in each
f the three mentioned cases. The approximate expression of characteristic function of the wire is used in the
.