Low-profile double-shell Halo antenna with wideband characteristic

Abstract

In this study, the characteristics of a wideband, low-profile, double-shell Halo antenna is investigated. The Halo antenna is a horizontally polarized antenna with a small diameter and a relative bandwidth of about 4%, which corresponds to a narrow bandwidth characteristic. Therefore, as a conventional broadband method, it is possible to increase the bandwidth of the Halo antenna while maintaining the antenna diameter by loading parasitic elements vertically above and below. However, the disadvantage of this method is that the antenna height increases owing to vertical stacking of the elements. In this study, a double-shell structure with the parasitic elements placed inside the Halo antenna is used to achieve a relative bandwidth of 9.3% while maintaining the antenna height and diameter.