Characterization of the near-field and the far-field for a vertically radiating antenna over a ground plane.

In this paper, few topics related to the near-field and far-field behavior of a vertically oriented antenna above a PEC ground plane is discussed. The very near-field is determined by the position where the wave impedance approaches free space impedance, and the phase of the wave impedance approaches zero. As one move further ahead the wave sphericity condition determines the transition from the radiative near-field to the radiating far-field of the antenna. This transition position changes linearly with the height of the transmitter above the ground plane. Thus for a reliable and efficient communication one should take care of this far-field criterion for optimum positioning of the transmitting and receiving antenna.