Helical-Shaped Antenna Array—Study of Input Impedances and Radiation Patterns

Abstract

A theoretical analysis of the input impedance and vertical radiation patterns of a three-turn helical array of twenty-five half-wave dipole antennae is presented. The dipole radiators are placed horizontally and are parallel to each other. The ground reflection is assumed to be negligible throughout the analysis. Four combinations of the radii r of the helices and separation between consecutive turns h of the helices are considered in terms of the operative wavelength. The input impedances in the above four cases are given in a tabular form. The input impedances of the different radiators are found to vary slowly from radiator to radiator. The sharp vertical radiation patterns for the two φ-planes for the four combinations of r and h are plotted and discussed.

Indexing Terms:

• Helical Beam Antenna Array
• Input Impedance
• Radiation Patterns
• Complex Excitation Current