Piksa, Petr (Department of Electromagnetic Field, Czech Technical University in Prague, Technicka 2, Prague 6, Czech Republic)
The paper investigates conical shapes of log-spiral antenna in the radiation pattern and the frequency independences of gain and axial ratio. Parametric study is based on numerical modelling using FEKO simulator. Unidirectional radiation pattern appears only at the lowest working frequency for a wider cone angle or appears wideband for the cone angle lower than 20deg. The 3dB beamwidth strongly depends on a cone angle and a rate of wrap, and ranges from 80 to 200deg.