Dual Circularly Polarized and Linearly Sweeping Leaky-Wave Antenna

In this letter, a dual circularly polarized periodic leaky-wave antenna based on spoof surface plasmon polaritons (SSPPs) with linearly sweeping beams is proposed. The antenna can simultaneously radiate left-handed circular polarization (LHCP) and right-handed circular polarization (RHCP) beams. Single-arm Archimedean spirals serve as radiators and are designed. Based on linearity analysis and curve fitting, SSPPs structure with potentially linear scanning ability are selected. Finally, the axial ratio (AR) and S-parameter for the proposed SSPPs antenna with spiral radiators are optimized around the broadside frequency using longitudinally asymmetric analysis. A prototype is fabricated and measured results show that the proposed antenna achieves a relative 3 dB AR bandwidth of 31.6% (8-11 GHz) with the same LHCP and RHCP scanning range of 65 degrees and linearly sweeping ability.