The reflectarray antennas [1] combine some of the best features of antenna arrays and reflector antennas. The reflectarray concept is based on the reflection properties of the individual cells. The required phase on the radiating aperture can be obtained by varying the parameters of each unit cell. In the literature, several configurations of reflectarrays have been reported in microstrip technology, e.g. [2-4]. However, at millimeter waves, the conductor loss becomes severe, and the efficiency of the antenna is reduced significantly. In contrast to patch antennas, dielectric resonator antennas (DRAs) exhibit low loss, broad bandwidth, small mutual coupling and higher radiation efficiency, e.g. [5]. Therefore, DRA reflectarrays are attractive in that frequency range. A first prototype based on this approach has been introduced previously in Ka-band [6]. In this work, the required phase shift is obtained by varying the height of the DRA, which requires a complex manufacturing process. In this paper, we introduce a new low-loss DRA reflectarray element with a metallic strip printed on the top of the DRA. The main idea of this topology is to vary the phase of the reflected field by changing the size of the strip and not that of the DRA itself. The main characteristics of the unit cell are first described in Ka-band. Then the proposed concept is validated experimentally in C-band. Experimental results are in good agreement with the numerical predictions.
展开▼
