On-Silicon efficient integrated DRAs for millimeter-wave energy harvesting solutions

This paper presents preliminary results of dielectric resonator antennas (DRAs), exploiting silicon, as possible candidates for compact energy harvesting system fully integrated on silicon. The antennas are designed to operate at 24 GHz using a 0.525-mm thick high resistivity silicon substrate. Different shapes and solutions are considered: first cylindrical and cuboid elements are characterized under the HEM11δ hybrid mode excitation and promising performance are demonstrated with a very good compromise between compactness and radiation performance: for a DRA with a volume as low as 7 mm3, a radiation efficiency of 75% and a maximum gain of 4.72 dBi have been obtained. Subsequently, a millimeter-wave rectenna, based on the proposed DRA, is designed, providing an RF-to-dc conversion efficiency of 33% for a received power of 8 dBm, with a maximum output dc voltage of about 3V. Based on these designs a fully integrated 2 x 2 silicon array is realized, for enhancing the energy harvesting capabilities in the mmWave range, while preserving the compactness of the entire system. In this case, the maximum gain of the antenna is equal to 7.3 dBi with a radiation efficiency equal to 60%.