2-D Scannable 40-GHz Folded Reflectarray Fed by SIW Slot Antenna in Single-Layered PCB

Folded reflectarray antenna features high gain, low profile, and low sidelobe level, but also faces several challenges in scannability, manufacturing, assembling, and integration with planar circuits, especially at millimeter-wave and terahertz frequencies. To alleviate these issues, this paper presents a slot antenna based on substrate integrated waveguide (SIW) to replace conventional horn. This SIW slot antenna is then inherently integrated with reflectarray elements in the same single-layered printed circuit board (PCB) for the first time. Moreover, this folded reflectarray is able to scan its narrow beams in 2-D, by controlling the polarizing grids. The whole reflectarray is fabricated by the commercial low-cost PCB process and can be highly integrated with planar active circuits. Measured results show that the proposed reflectarray achieves a 2-D scanning zone of 14° × 14°, a gain of 27.4 dBi, and a cross-polarization level less than -24 dB. The proposed folded reflectarray is promising for several application scenarios including millimeter-wave highresolution imaging and fifth-generation communications.