Wideband waveguide antenna using stepped L-shaped probe for wide-angle circular polarization radiation

Abstract

A circularly polarized (CP) waveguide antenna using L-shaped probe is presented. The proposed antenna can cover the UWB (Ultra Wideband) high-band (34.3%: 7.25 GHz–10.25 GHz in Japan) with 3-dB axial ratio (AR) having a wide range of angle in the radiation patterns. For obtaining this performance, a stepped structure is introduced in the L-shaped probe. The optimization of the stepped structure can control the amplitude ratio of the two orthogonal modes of electric field. This can enhance the AR bandwidth of the previously proposed waveguide antenna using an L-shaped probe and parabolic short wall. Finally, the proposed structure achieves 39% of 3-dB bandwidth keeping a wide angle for radiating CP in an angle of around 135°.