A circularly-polarized antenna is provided, and includes a conductive backplane with a plurality of panels, a vertical array of patch radiators disposed on one of the backplane panels, and a feed stripline disposed on the backplane panel. The backplane panels are vertical, planar, rectangular and form a right prism. The vertical array has a radiator spacing of one wavelength, each radiator has a face and four edges, and each edge has a length of approximately one half wavelength. The feed stripline includes an input coupled to a coaxial feed cable, and a pair of outputs, orthogonal in position and phase, coupled to each of the radiators.