چكيده به لاتين
Recently, a strong interest has emerged in energy harvesting and wireless power transfer technologies. These technologies significantly increase the mobility and also improve the reliability of low power wireless devices such as wireless sensors for a harvesting application, the captured microwave energy must be channeled to a resistive load which models the input impedance of a rectifying circuit in a complete harvesting system.
Several works improved the performance of metasurface harvesters such as employing ground backed CSRR to increase the bandwidth of the harvester22 and using an electric_field-coupled inductive-capacitive (ELC) resonator to achieve a metasurface harvester with near-unity efficiency. However, very little effort focused on improving the harvesting effciency for incident electromagnetic waves having different polarizations.
Thist thesis presents a polarization-independent metasurface harvester composed of an ensemble of electric-inductive-capacitive (ELC) resonators. The ELC resonator has full symmetry in a way that its behavior is highly insensitive to the polarization of the incident wave. Loading the resonators with resistors (which model the input impedance of a rectifying circuit in a harvesting system), it is shown that the metasurface absorbs the incident electromagnetic wave energy, with nearly unity effciency, irrespective its polarization while simultaneously delivering the absorbed power to the loads. As a proof of concept, a metasurface harvester composed of a 9×9resonators array working at 2.45 GHz was fabricated. Near-unity efficiency of the metasurface was demonstrated using full-wave numerical simulation for a wide range of polarization angles. Laboratory tests showed strong agreement between the simulation results and the measurements.
In the next chapter, a dual-band polarization independent energy harvester is proposed. But efficiency of 2nd band is lower than first band. To improve the efficiency of both bands, the structure has been optimized. Optimization done with BPSO (Binary Particle Swarm Optimization) method. Simulation results show that optimized unit cell has efficiency of more than 0.9 for every polarization angle.
