Design of a shaped omni directional circular waveguide antenna

This paper describes the design, simulation and optimization of a shaped omni-directional circular waveguide antenna at 38 GHz. The proposed antenna consists of a rectangular waveguide, rectangular to circular transition, circular waveguide, metallic cone and a dielectric holder. The designed antenna has been simulated on ANSOFT HFSS EM Simulator using proper boundary conditions. Circular waveguide is excited by TM₀₁ mode to properly generate the required pattern. The radiation pattern of circular waveguide has been modified using metallic cone. The antenna has omni pattern in azimuth plane and -10 to +45 degree coverage in elevation plane. The proposed antenna has the advantage to be robust, low cost and easy to fabricate being in waveguide configurations. Simulated VSWR less than 1.4 has been achieved for frequency range 37-40 GHz. The Omni gain of antenna is greater than 0 dBi over the frequency band.