Leaky-wave antenna with switchable omnidirectional conical radiation via polarization handedness

Reconfigurable antennas capable of beam-steering offer an efficient solution to optimize the use of the crowded wireless medium and can serve as a multifunction antenna. Beam-steering is often achieved by antenna geometry switching at the expense of hardware complexity. Here, polarization is used to realize beam-steering without the need of antenna geometry modification. Depending on the handedness of the feed, backward or forward conical radiation is demonstrated in a ∼13λ0-long short-circuited helically slotted waveguide antenna. Tapering the slit width with a Taylor distribution reduces the measured sidelobe levels by ∼3 dB in average and results in a realized gain of 10-13 dB and 11-13 dB for right-handed (backward radiation) and left-handed circularly polarized (forward radiation) feeding, respectively, in the bandwidth from 8.5 to 9.5 GHz.