A cylindrical DR rod antenna fed by a short helix

Abstract

A dielectric rod antenna has been shown to have a high directivity and a helical antenna is inherently relatively high-gain and circularly polarized. A suitable method can be used to put them together so that desirable characteristics are obtained. We use a short helix to feed a DR (dielectric resonator) rod antenna. The helix itself is in turn excited by a coaxial cable. It is found that a high directivity as well as circular polarisation resulted. The use of the helix greatly simplified the feeding mechanism of the DR rod while also provided a circularly polarized source which other conventional methods such as waveguide feeding cannot. When EM waves of a suitable frequency are excited the high permittivity DR acted as an effective traveling wave antenna so that a high gain was obtained. This antenna retains the characteristic of both the helical and DR rod antennas. It was reported that an aperture-coupled helical antenna has been designed. It can be envisaged that this design has the advantage of ease of fabrication for helix array constructions. The novel structure can be employed in our feeding helix so that an extremely high gain DR rod antenna array can be constructed for satellite communication. In our preliminary study, we measured the antenna's VSWR, radiation pattern, bandwidth and axial ratio. The operating frequency was chosen to be in the C-band.