Dielectric resonator antenna reflectarray in Ka-band

A reflectarray antenna combines some of the best features of reflector antennas and phased array antennas. It consists of a primary source illuminating a planar surface composed of many unit-cells. By varying the parameters of each cell, it is possible to control the main beam direction and shape the beam. Many prototypes in microstrip technology have been proposed recently. Nevertheless, at millimeter waves, the conductor losses become severe, and the antenna efficiency may drop significantly. On the other hand, dielectric resonator antennas (DRAs) have been introduced due to their low loss, relatively wide bandwidth and high radiation efficiency. Due to these advantages, a first DRA reflectarray was developed in Ka-Band; in that work, the required phase delay was achieved by varying the DRA length, and the reflectarray was made of DRA blocks of various size. We have introduced recently an alternative solution based on strip-loaded DRAs. In this design, the desired phase delay is only controlled by the length of the metallic strip printed on top of constant-size DRA; this concept has been validated experimentally in C-band in waveguide simulators. In this paper we apply similar ideas in Ka-band (30 GHz), and we present the design and measurement of a complete 24x24-element reflectarray.