Single-fed crossed V-dipoles with four masts for circular polarization

In this paper, a new single-fed crossed V-dipole antenna for a circular polarization is proposed. This antenna is single-fed with four arms supporting the two V-dipoles on the reflector used as a balun as well as a 90degrees phase shift divider. The symmetrically placed supporting arms can be viewed as transmission lines. From the current distributions of the equivalent circuit of these lines, the input impedance of the V-dipoles and the circular polarization condition with regard to the antenna height and the stub location are derived. Based on these quantities, a circularly polarized antenna is designed and its characteristics are derived. It is found that there exists a structure for which the axial ratio can be made substantially wider than other antennas with a size of one-half wavelength. By means of experiments, the validity of the theoretical results is confirmed. (C) 2002 Wiley Periodicals, Inc.