Steering of the circularly polarized beam from a spiral antenna

Abstract

The circularly polarized axial and conical beams from a two-arm spiral antenna are investigated and the radiation phase distributions around the antenna axis are clarified. A tilted beam is created by superimposing the conical beam onto the axial beam. The tilted beam is steered in the azimuth plane when the two arms are excited by different amplitudes and phases. The beam direction of the tilted beam estimated using formulated phase distributions agrees with that obtained from a numerical analysis. The estimation with the formulated phase is simple and has the superiority over the determination of the complex and time-consuming numerical analysis.