Circularly polarized transmitting antenna employing end-fire elements

Claim 1

An antenna assembly for transmitting signals of wavelength λ, comprising an elongated electrically conductive supporting structure, at least one bay including at least two driven antennas of orthogonal polarizations carried by said support structure and defining a common radiation axis extending therefrom, means for feeding electrical energy to said driven antennas, and at least one end-fire parasitic director having a longitudinal axis and comprising at least one discrete conductive member disposed along said longitudinal axis, said discrete member having a major dimension in the planes of electric field vector of transmitted signals of wavelength λ of at least λ/4 and no more than λ/2 said end-fire director being so positioned relative to said driven antennas and support structure as to alter the shape of the radiation patterns of said driven antenna and support structure, and a metal member parallel to the elongated support structure axis of a dimension in a plane transverse to said axis of less than λ/4 and greater than λ/2 long in direction parallel to the axis, intersecting the radiation axis of the driven antennas and so located that both driven antennas are between said metal member and the said supporting structure.