Design of millimeter wave dual-polarized multibeam antenna array with a boresight beam

A design of millimeter wave (mm-wave) dual-polarized multibeam antenna array (MAA) with a boresight beam is presented. In order to generate a boresight beam, a 5 × 6 Butler matrix based on three-way directional couplers is designed as the beamforming network, which achieves equal power division and −60°, +120°, 0°, −120°, +60° progressive phase differences among the output ports when the five input ports are excited, respectively. By four-layer design, the two 5 × 6 BMs for horizontal polarization (HP) and vertical polarization (VP) are constructed. The patch is used as radiator element, and the HP and VP wave are excited by aperture coupling and microstrip feed, respectively. A prototype is fabricated and measured to verify the design. The measured results show that the designed mm-wave dual-polarized MAA can generate five radiation beams including a boresight beam and the five beams with HP and VP cover the range of ±50° at 28 GHz. In addition, the designed mm-wave dual-polarized MAA can be a potential option for mm-wave multibeam application.