3-D Printed Millimeter-Wave Metal-Only Dual-Band Circularly Polarized Reflectarray

This article presents 3-D printed metal-only dual-band millimeter-wave circularly polarized (CP) reflectarrays (RAs). The RAs' unit cell (UC) is made of an anisotropic metal brick mounted on a full metal ground. In-plane rotating the metal brick introduces geometric Pancharatnam-Berry (PB) phase shifting, and vertically adjusting the position of the UC provides propagation phase shifting. The geometric PB and propagation phase shifting offer two different degrees of freedom, enabling independent wavefront shaping of CP wave over dual-band. Specifically, the low-band CP beam shaping solely depends on the propagation phase. In contrast, the high-band CP beam shaping depends on the geometric PB and the propagation phases. The coupling issue between dual-band is minimal because of the unique dual-band phase-shifting methods. In addition, 3-D printed dual-band left-hand CP (LHCP) horn antennas are designed, printed, and used as the feed. To demonstrate, two RA antennas with different dual-band CP beam directions are fabricated and measured.

Automated summary

This article presents the design and fabrication of 3-D printed metal-only dual-band millimeter-wave circularly polarized reflectarrays. Through the adjustment of geometric Pancharatnam-Berry phase and propagation phase, independent wavefront shaping of circularly polarized waves over dual-band is achieved. Additionally, 3-D printed dual-band left-hand circularly polarized horn antennas are used as the feed.