An array of elliptical cavity backed helical elements for L-band satellite to mobile communication systems

An array of cavity backed helical elements has been developed to satisfy the specification for the mobile antenna for the AUSSAT L-band satellite to mobile system. The array uses a circular array of elements with elliptical cavities, and beam switching to achieve the desired coverage. The optimised elliptical cavity provides additional gain over its circular counterpart and useful beam shaping which is exploited in the arrangement of the antennas in the array. This shape of cavity does degrade the axial ratio to a degree but this is still well within specification. A detailed experimental study of the performance of these cavity backed elements has been carried out. The complete array could provide a simple, rugged and inexpensive steerable beam antenna having the desired gain and coverage for the system. This would be a competitive to electrically steerable phased array and mechanically steerable solutions to the problem