Radiated Field from a Thin Half-Wave Dipole Excited by a Single-Cycle Sinusoid
Abstract
The primary objective is to study the behavior of the radiated electric field from a half-wave dipole in free space excited by a single-cycle sinusoidal voltage. In order to accomplish this we first compute analytically the radiate electric field from a thin electric dipole antenna, excite at the center by a sinusoidal voltage of finite duration T using an approximation. This approximation consists of retaining only the zero-order solution for the current along the antenna in the frequency domain. Then the time-dependent current as well as the radiated electric field are calculated. For a matched system, the time dependent current along each half-section of the dipole is made up of a signal from the feed point and a signal reflected from the end. On the other hand, the radiated electric field consists of four signals exhibiting that radiation takes place only from the discontinuities of the dipole antenna. For a half-wave dipole at the carrier frequency f sub o, the time dependent current along the antenna as well as the radiated field, due to a single-cycle sinusoidal excitation, are plotted as functions of a normalized time. Both current and the radiated electric field are extended in time due to the reflection of current from the end points of the dipole antenna. It appears that the spectral bandwidth of the radiated electric field is narrower than that of the exciting voltage pulse. This phenomenon may be due to the filtering effect of the half-wave dipole. Keywords: Dipole antenna; Transient response.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 31, 1989
- Accession Number
- ADA216706
Entities
People
- S. N. Samaddar
Organizations
- United States Naval Research Laboratory