The yagi-helix: A multi-director configuration for the backfire-helix antenna

Analyses on the diameter of the ground plane of helical antennas show that, when the diameter of this plane is slightly smaller than the one of the helix itself, backfire radiation is achieved. Considering this ground plane as a director, the addition of more ground planes - or directors - is proven to increase the directivity of the antenna. With these reduced ground planes not causing any blockage in the axial direction, its good circular polarization and its broadband characteristic, this antenna is a suitable choice for feeding parabolic dishes for satellite communications. The construction of the antenna and its subsequent measurements are described, as well as an application of it serving as the feed for a parabolic dish.