Beam-Steerable Helical Antenna Using Plasma Reflectors

The aim of this paper is to investigate the steering mechanism of the beam pattern of a helical antenna using a half-cup plasma reflector. To this end, variations of the radiation characteristics and also the direction of the main beam of the antenna due to changes in the dimensions of the half-cup plasma reflector, including its diameter and height, are numerically computed and analyzed. The simulation results show that using this structure, the beam direction can be altered in 3-D space within a solid angle of ±10°. Also, it is highlighted that the half-cup plasma reflector may adversely affect the polarization of the helical antenna. Therefore, a trade-off between polarization and performance of an antenna based on a parametric study has to be made. Thus, in this investigation, the axial ratio of the antenna is also analyzed for each dimension. For demonstration, the study is used for the design of a circularly polarized helical antenna with a half-cup plasma reflector. Good agreement between the numerically calculated and measured results validates the presented study.