The quadrifilar helix antenna

The characteristics of the quadrifilar helix antenna [1] and [2], a broad-band high-gain device, are described in detail. Experimental data on beam patterns, impedance, and axial ratio are given for both the circularly polarized quadrifilar helix antenna (QHA) and the linearly polarized counterwound quadrifilar helix antenna (CQHA). Bandwidths in excess of 5:1 are obtained. The low frequency behavior is discussed. Computation of the QHA characteristics by moment methods [3] is described and computed data on beam patterns and current distributions are given.