Octafilar helix antennas for mobile satellite handsets

The paper reports the radiation characteristics of an octafilar helix antenna on a portable handset: the far field pattern; the polarization pattern; the antenna gain; the axial ratio; the input impedance; the near field pattern. A wire-grid model, which replaces the conducting surface with a wire mesh, is used. The current distribution along the antenna as well as the portable handset is determined using the method of moments. The radiation characteristics of octafilar helix antennas on conducting boxes of different dimensions are illustrated. It is shown that the level of the radiation pattern and the polarization pattern is decreased, the antenna gain is decreased, and the input reactance is increased as the height of the conducting box is increased. When the width or the thickness of the conducting box is changed, the pattern is distorted.