2025 Volume E108.B Issue 5 Pages 610-621
A fully planar and circular beam-switching antenna module with 360° in-plane coverage is proposed for collision avoidance radar payload of drones. It consists of a novel dual-mode single-pole-multi-throw switch, a proposed circular beamforming network (CBFN), one-bit phase shifters, and quasi-Yagi antennas. The switch can redirect the input power to any one of the output ports (single-ON mode) or any two adjacent output ports (dual-ON mode). Owing to these two modes, the total beam number doubles. The CBFN is constructed by arranging the modified sub-matrices (MSMs) side-by-side into a circle with adjacent MSMs sharing their edge components (ECs). The MSMs are binomial power dividers with the ECs replaced by three-way power dividers. The ECs can split the power from the switch into adjacent MSMs and the EC at the following stage. For verification, a 12-beam prototype module designed at 5.8 GHz was fabricated and tested. Besides the agreement between the simulated and measured results, the 12 beam patterns exhibit highly similar shapes with sidelobe level < -13 dB and less-than-1-dB gain variation between the single-ON and dual-ON modes. The consistent 30° half-power beamwidths of the 12 beam patterns altogether cover the entire horizontal plane with minimal overlaps.
