الفهرس 
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Abstract
The dominant focus of this thesis research is on studying the transient radiated electric field resulting from a half-wave thin dipole and linear array of dipoles excited by a single cycle sinusoidal pulse. This analysis is based on the modified zero-order current which includes the mismatch between the exciting source and the antenna. The time history of this current is demonstrated at different points along the dipole axis. The assumption used in deriving such a modified zero-order current are: the radius of the dipole is much less than
21
The wavelength and the length thickness parameter!”} = 2ln— -»cc. where 2/ is the total
a
antenna length and a is the conductor radius.
More specifically, the approximate closed form expression of such time dependent current is made up of a current pulse traveling from the fed-point and a reflected one from the end point. However, the radiated electric field consists of five overlapping signals exhibiting that radiation takes place only from the discontinuities of the dipole antenna. Both the current and the radiated electric field are extended in time due to the reflection of current from end points of the dipole antenna. In addition, it appears that the spectral bandwidth of the radiation electric field is narrower than that of the exciting voltage pulse. This phenomenon may be due to the filtering effect of the hah0-wave dipole.
The half-wave dipole antenna is analyzed by a straightforward application of the finite difference time-domain (FDTD) method. The computed transient radiated electric field, is shown to be in excellent agreement with the analytical solution at different observation angles. The moment of method (MoM) with triangle basis function and impulse as a weighting function, is applied to Hallen’s integral equation. Consequently, the time history of the transient current at any point along the dipole axis with a finite thickness is computed using the fast Fourier transform (FFT).