الفهرس | Only 14 pages are availabe for public view |
Abstract Electromagnetics have an important role in power and energy industry. The wireless communication industry has grown explosively and microwave wireless power transmission (MWPT) research has received a great attention. Rectenna is a rectifying antenna which is essential for wireless power transmission. It converts the radio frequency wave into DC power energy. Rectenna can be used for many applications such as mobile battery charging, radio frequency identification, medical implant devices and infrared power harvesting which is considered the major frequency band of the solar spectrum to produce DC power energy from incoming solar energy. This thesis presents several designs of rectenna systems in different frequency range applications. Cylindrical dielectric resonator (CDRA) antenna is used to exhibit left-hand and right-hand circular polarizations. The antenna is used to feed the reflectarray to increase its gain in a certain direction. A single piece of dielectric material sheet is divided into 17x17 unit-cell elements to build up the reflectarray. The reflectarray is designed at 5.8 GHz at C-band to concentrate the incident waves on the receiving antenna. It is light weight, small size and low cost. Rectifying circuit components composed of a matching network, two-stage voltage doubling circuit, DC-pass filter and a resistive load are designed. This rectification circuit has the maximum conversion efficiency of 71% at 5.8 GHz on the load of 1200 Ω. Different designs of graphene based geometrical diodes coupled with nanoantennas for infrared (IR) energy harvesting are investigated. The geometrical diode is an electronic device in which the current flow through it is controlled by its geometry. The I-V Abstract III characteristics of the graphene based geometrical diodes are calculated by the Monte Carlo simulation. Different shapes of graphene geometrical diodes, arrowhead, modified staircase, and arc shape geometries have been examined. Rhombus shaped dipole nanoantenna coupled to geometric diode for energy harvesting at 19.4 THz is used with an arcshaped geometric diode which is placed in the gap between the ipole arms to produce output voltage 16.5 μV. Two approaches for enhancing the received voltage of nanoantenna energy harvesting at 19.4 THz are investigated. In the first approach, a transparent trasmitarray is used to focus the electromagnetic waves on the surface of the nanoantenna coupled to the geometric diode. The received voltage is increased from 16.5 μV for single nanoantenna to 97.6 μV for the transmitarray coupled to the nanoantenna. In the second approach, Yaginanoantenna arrangement is used to enhance the directivity of the single element that coupled to the transmitarray and the output received voltage increased to 0.202 mV. |