A Multibeam Folded Reflectarray Antenna With Wide Coverage and Integrated Primary Sources for Millimeter-Wave Massive MIMO Applications

A millimeter-wave multibeam folded reflectarray antenna (FRA) with wide coverage in the azimuth plane and integrated planar primary sources for massive multiple-input multiple-output wireless communications is proposed. The substrate-integrated waveguide series-fed aperture-coupled rectangular patch antenna arrays are used as the primary sources, which makes it possible to be integrated with transceiver circuits seamlessly. A bifocal design methodology is used for improving the beam coverage and performance. A 19-beam prototype which consists of three seven-beam FRAs is designed, fabricated, and measured, enabling 30° coverage with a beam crossing level of −3 dB. The measured maximum beam gain is 25.9 dBi at 42 GHz, while the measured overall bandwidth, i.e., $\vert S_{11}\vert < -10$ and 3 dB gain bandwidth, is 39–43 GHz. The proposed antenna has the advantages of easy fabrication, high gain, low cost, low profile, wide angular coverage, and co-planar integration with transceiver circuits, etc.