الفهرس 
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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.