Circular Array of Endfire Yagi-Uda Monopoles With a Full 360° Azimuthal Beam Scanning

A multiport circular array of endfire Yagi–Uda monopoles with a full beam coverage of the azimuth plane is developed in this communication. The known issue that a vertical monopole antenna on a finite-sized horizontal ground plane radiates an elevated beam is investigated. It is demonstrated that this effect can be mitigated by inserting resonant structures, i.e., slots, into the ground plane to redirect the radiated beam back to the horizontal direction. An endfire monopole-based Yagi–Uda antenna is then developed that radiates a directed endfire beam. A multiport circular array of these antennas is optimized to provide beam coverage over the full 360° azimuthal plane. A sector of this circular array of monopole-based Yagi–Uda antennas was simulated, fabricated, and measured to verify the concepts. Good agreement between the simulated and measured results is confirmed.