Radiating elements for hemispherically scanned arrays

The problem of obtaining hemispherical coverage using an electronically steered antenna beam is considered. Radiating elements consisting of combinations of slots, parasitic dipoles, and surface wave structures were investigated for this application. Both planar and cylindrical supporting structures were used. It was found that such elements showed enhanced radiation near the horizon in both the -plane and the -plane. Patterns were measured on an eight-element linear array of slots covered by a surface wave structure. When the beam was scanned electronically to endfire, the pattern was enhanced by several dB over that obtained from the array without the surface wave structure.