An mmWave FZP-Based Phased Array

The development of millimeter-wave phased array based on the digital beamforming architecture needs to overcome a physical-level challenge due to the contradiction between the massively integrated TR devices and the compact volume for thermal dissipation. In this work, we demonstrate an analog beamforming solution based on a reconfigurable Fresnel-zone-plate (RFZP) antenna for 28-GHz phased array. The proposed RFZP including $\boldsymbol{16}\times\boldsymbol{8}$ unit cells based on active frequency selective surface (FSS) with varactor diodes to implement a continuous $\boldsymbol{180}^{\boldsymbol{\circ}}$ phase tunability. The measured scan ranges up to $\pm\boldsymbol{50}^{\circ}$ and $\pm\boldsymbol{30}^{\circ}$ at horizontal plane and vertical plane, respectively. The proposed RFZP antenna is an attractive solution for millimeter-wave beamforming.