Cavity mounted Axial-mode wire helix

Image of the Cavity mounted Axial-mode wire helix.

The requirement for a broadband elliptically-polarised antenna which can be flush-mounted on high speed aircraft is common in the aerospace industry. This antenna inherently fulfils the broadband, elliptical polarisation requirements. It is also mechanically simple, can be flush-mounted and is relatively small compared to other antennas that could provide similar operation at a given frequency.

The cavity mounted axial-mode wire helix provides good polarisation purity and constant on-axis-gain over the operating band, as shown in the following 3D circular polarised gain pattern image at three different frequencies in the operating band.

Typical circularly polarised gain patterns at the minimum, centre and maximum frequencies.
Typical reflection coefficient versus frequency.