Near-field focusing properties of colinear dipole arrays

Antenna arrays are normally characterized in terms of their far-held radiat ion patterns, beam width and directive gain. However, for some applications the army is required to act as a lens and is focused in the near-field zon e. The focusing is done by adjusting the phase of the array elements. In th is study the focusing properties of a linear dipole array are investigated to determine the parameters that influence focusing efficiency. In particul ar, the effects of the array size, focusing distance, frequency of operatio n, and spacing between elements are studied. The simulations are carried ou t using the method of moments, and show that the array size and phase distr ibution play dominant roles in the focusing process. Other parameters have minimal effects.