Design of an asymmetric capped biconical antenna for constant beam direction over a desired range of frequencies

In this paper a new wideband biconical antenna with shaped radiation pattern is presented. This biconical antenna has two different elements. Each element consists of a simple cone and an annular cap playing a role as shaping of E-plane radiation pattern. By introducing several geometric features, the beam shaping behavior of the proposed antenna over a desired range of frequencies is investigated. To improve the impedance matching, decrease the feeding cable effect on the antenna performance and simplify the fabrication process, a coaxial cable is embedded in antenna feed port. The simulated and measured results show a wideband impedance bandwidth (387 MHz-7.13 GHz), constant beam direction in E-plane over a desired range of frequencies and omnidirectional H-plane pattern for the proposed antenna.