Abstract
In ambient energy harvesting applications, metamaterials and metasurfaces are useful in localizing and absorbing energy from the surroundings. This chapter reviews past achievements, recent developments and future trends in metamaterial-based radio-frequency (RF) energy harvesters. The chapter begins by introducing metamaterial energy harvesters from a general perspective, covering mechanical, acoustic, and electromagnetic metamaterial energy harvesters. The subsequent section focuses specifically on the working principle of electromagnetic metamaterial energy harvesters in the RF regime. To enhance understanding of the absorption mechanism and performance evaluation, a simulation of an Omega-ring-shaped metamaterial harvester operating at a frequency of 5.8 GHz is demonstrated. The absorption efficiency, harvesting efficiency, and conversion efficiency of the metamaterial harvester are determined and discussed. Furthermore, the state-of-the-art design of metamaterial RF harvesters and their respective performance are reviewed.
TopAmbient energy refers to the energy that is available in our surrounding environment, which can take different forms and carried by elastic waves (vibration), acoustic waves (sound), and electromagnetic waves. These energy are dissipated through different mechanisms and can be harvested using various methods and materials. This section provides an introduction to the primary types of ambient energy sources and the utilization of metamaterials for energy harvesting.
Key Terms in this Chapter
Wireless Power Transmission: A process of transmitting electromagnetic power through vacuum or atmosphere without connecting wires or substances.
Metamaterial: An artificial engineered structure which exhibits properties not usually found in natural materials.
Absorption Efficiency: The ratio of the total time-average power absorbed by the metamaterial structure to the total time-average power incident to the metamaterial structure.
Energy Harvester: A device which collect energy such as acoustic, mechanical, and electromagnetic energy and convert them into useful electrical power.
Harvesting Efficiency: The ratio of total time-average power delivered to the resistive load the total time-average power incident to the metamaterial structure.
Rectenna: Rectifying antenna which consists of an antenna and a rectifying circuit.
Conversion Efficiency: The ratio of the total time-average power delivered to the resistive load to the total time-average power absorbed by the metamaterial structure.