A Circularly Polarized Multi-beam Antenna Based on SIW Pillbox Beamforming Network

This paper proposed a circularly polarized multi-beam antenna. This antenna is based on a substrate integrated waveguide (SIW) pillbox beamforming network (BFN). The proposed antenna is composed of a SIW pillbox fabricated by dual-layered printed circuit broad (PCB) and a circular polarizer fabricated by computer numerical control (CNC) technology. Five SIW horns are placed at the focal plane of the pillbox BFN. The horns can generate the output signals with different phase gradients when they placed at the different position of the focal plane, which can realize the multi-beams in different directions by switching the feeding ports. The CNC circular polarizer is loaded at the end of the pillbox ports to realize circular polarizations. The antenna is designed at the frequency of 10 GHz, and the simulated results prove that the proposed structure can realize a 24 deg beam scanning range with the maximum gain of 15.25 dBi. This antenna has advantages in circularly polarized radiation and low-cost passive beam scanning capability, making it suitable for radar and wireless communication systems.