Radiation field of an elliptical helical antenna

Rigorous expressions for the radiation field of a helical antenna of elliptical shape are derived on the assumption of a traveling-wave type of current distribution along the helix conductor. The analysis is valid for integral and nonintegral numbers of turns. These expressions for the general helix are employed to determine the fields for the limiting case of a circular helical antenna, and the results are essentially the same as those derived by both Knudsen and Kornhauser. Allowing the ellipse to degenerate to the other limiting case, a solution for the radiation field is obtained for the planar or commonly known zig-zag antenna. Therefore, it is possible to achieve a truly circularly polarized field with an elliptical helix of slight ellipticity.