Omnidirectional circularly-polarized antennas

A general technique has been developed for achieving a circularly polarized antenna with omnidirectional azimuth coverage. The technique permits the immediate design of such an antenna with a great variety of possible vertical coverage patterns. The problem of satisfying any desired vertical coverage has been attacked by postulating three basic types-a broad beam, a narrow beam and a shaped beam. Designs for each of these three types have been achieved.