2x2 array of wire helix antennas
Image of the 2x2 array of wire helix antennas.

Sequentially rotating elements to form an array was originally investigated for increasing the main-beam axial ratio of patch antennas [Kraft].Using this technique with an axial mode helix antenna, the gain and main-beam polarisation is improved w.r.t a single element.

This axial-mode helix array consists of four identical helices placed in a 2-by-2 grid, rotated sequentially about their axis, and fed sequentially out of phase.

Typical polarisation specific gain pattern at the centre frequency

A comparison of the gain versus angle and the axial ratio versus frequency on broadside between a single axial-mode helix and a sequentially rotated array of axial-mode helices illustrates the performance improvement.

Typical normalised circularly polarised gain versus angle pattern at the centre frequency of a sequentially rotated array compared to a single element
Typical axial ratio on boresight versus normalised frequency of a sequentially rotated array compared to a single element

U. R. Kraft, "Main-beam polarization properties of four-element sequential-rotation arrays with arbitrary radiators", IEEE Transactions on Antennas and Propagation, vol. 44, no. 4, pp. 515-522, 1996.