Some effects of asymmetric excitations on dipole radiators

Abstract

The recent model due to Shen, Wu, and King for the current distribution along the asymmetrically-driven thin cylindrical antenna is used in the calculation of current and far-field values for several cases of interest. The graphs show how the current distribution approaches the limiting sinusoidal assumption as the generator location is moved toward a free end. The antenna conductor thickness is shown to cause decaying sinusoidal variations on the radiation fields from the half-and full-wave dipoles having large excitation asymmetries. The model was found to yield accurate current amplitudes for dipoles at least 0.30\lambda in total lengths; however, the current phase is inaccurate for points closer than about 0.025\lambda from a free end. This latter value is also the restriction on how close the generator may be from the free end.