21-08-2014, 03:23 PM
WIRELESS MOBILE PHONE CHARGING SEMINAR REPORT
[attachment=66852]
INTRODUCTION
To start with, to know what a spectrum is: when white light is shone through a prism it
is separated out into all the colors of the rainbow; this is the visible spectrum. So white light is
a mixture of all colors. Black is NOT a color; it is what you get when all the light is taken
away. Some physicists pretend that light consists of tiny particles which they call photons.
They travel at the speed of light (what a surprise). The speed of light is about 300,000,000
meters per second. When they hit something they might bounce off, go right through or get
absorbed. What happens depends a bit on how much energy they have. If they bounce off
something and then go into your eye you will "see" the thing they have bounced off. Some
things like glass and Perspex will let them go through; these materials are transparent.
Black objects absorb the photons so you should not be able to see black things: you
will have to think about this one. These poor old physicists get a little bit confused when they
try to explain why some photons go through a leaf, some are reflected, and some are
absorbed. They say that it is because they have different amounts of energy. Other physicists
pretend that light is made of waves. These physicists measure the length of the waves and this
helps them to explain what happens when light hits leaves. The light with the longest
Microwave Region
Microwave wavelengths range from approximately one millimeter (the thickness of a
pencil lead) to thirty centimeters (about twelve inches). In a microwave oven, the radio waves
generated are tuned to frequencies that can be absorbed by the food. The food absorbs the
energy and gets warmer. The dish holding the food doesn't absorb a significant amount of
energy and stays much cooler. Microwaves are emitted from the Earth, from objects such as
cars and planes, and from the atmosphere. These microwaves can be detected to give
information, such as the temperature of the object that emitted the microwaves.
Microwaves have wavelengths that can be measured in centimeters! The longer
microwaves, those closer to a foot in length, are the waves which heat our food in a
microwave oven. Microwaves are good for transmitting information from one place to
another because microwave energy can penetrate haze, light rain and snow, clouds, and
smoke. Shorter microwaves are used in remote sensing. These microwaves are used for
clouds and smoke, these waves are good for viewing the Earth from space Microwave waves
are used in the communication industry and in the kitchen as a way to cook foods. Microwave
radiation is still associated with energy levels that are usually considered harmless except for
people with pace makers.
Magnetron
Magnetron is the combination of a simple diode vacuum tube with built in cavity
resonators and an extremely powerful permanent magnet. The typical magnet consists of a
circular anode into which has been machined with an even number of resonant cavities. The
diameter of each cavity is equal to a one-half wavelength at the desired operating frequency.
The anode is usually made of copper and is connected to a high-voltage positive direct
current. In the center of the anode, called the interaction chamber, is a circular cathode.
The magnetic fields of the moving electrons interact with the strong field supplied by
the magnet. The result is that the path for the electron flow from the cathode is not directly
to the anode, but instead is curved. By properly adjusting the anode voltage and the strength
of the magnetic field, the electrons can be made to bend that they rarely reach the anode
and cause current flow. The path becomes circular loops. Eventually, the electrons do reach
the anode and cause current flow
Slotted Waveguide Antenna
The slotted waveguide is used in an omni-directional role. It is the simplest ways to
get a real 10dB gain over 360 degrees of beam width. The Slotted waveguide antenna is
a Horizontally Polarized type Antenna, light in weight and weather proof.3 Tuning screws are
placed for tweaking the SWR and can be used to adjust the centre frequency downwards from
2320MHz nominal to about 2300 MHz .This antenna is available for different frequencies.
This antenna, called a slotted waveguide, is a very low loss transmission line. It allows
propagating signals to a number of smaller antennas (slots). The signal is coupled into the
waveguide with a simple coaxial probe, and as it travels along the guide, it traverses the slots.
Each of these slots allows a little of the energy to radiate. The slots are in a linear array
pattern. The waveguide antenna transmits almost all of its energy at the horizon, usually
exactly where we want it to go. Its exceptional directivity in the elevation plane gives it quite
high power gain. Additionally, unlike vertical collinear antennas, the slotted waveguide
transmits its energy using horizontal polarization, the best type for distance transmission.
RECEIVER SECTION
The basic addition to the mobile phone is going to be the rectenna. A rectenna is a
rectifying antenna, a special type of antenna that is used to directly convert microwave
energy into DC electricity. Its elements are usually arranged in a mesh pattern, giving it a
distinct appearance from most antennae. A simple rectenna can be constructed from a
Schottky diode placed between antenna dipoles. The diode rectifies the current induced in the
antenna by the microwaves. Rectenna are highly efficient at converting microwave energy to
electricity. Some experimentation has been done with inverse rectenna, converting electricity
into microwave energy, but efficiencies are much lower--only in the area of 1%. With the
advent of nanotechnology and MEMS the size of these devices can be brought down to
molecular level. It has been theorized that similar devices, scaled down to the proportions
used in nanotechnology, could be used to convert light into electricity at much greater
efficiencies than what is currently possible with solar cells. This type of device is called an
optical rectenna. Theoretically, high efficiencies can be maintained as the device shrinks, but
experiments funded by the United States National Renewable energy Laboratory have so far
only obtained roughly 1% efficiency while using infrared light. Another important part of our
receiver circuitry is a simple sensor. This is simply used to identify when the mobile phone
user is talking. As our main objective is to charge the mobile phone with the transmitted
microwave after rectifying it by the rectenna, the sensor plays an important role. The whole
setup looks something like this.
Sensor Circuit
The sensor circuitry is a simple circuit, which detects if the mobile phone receives any
message signal. This is required, as the phone has to be charged as long as the user is talking.
Thus a simple F to V converter would serve our purpose. In India the operating frequency of
the mobile phone operators is generally 900MHz or 1800MHz for the GSM system for
mobile communication. Thus the usage of simple F to V converters would act as switches to
trigger the rectenna circuit to on.
A simple yet powerful F to V converter is LM2907. Using LM2907 would greatly
serve our purpose. It acts as a switch for triggering the rectenna circuitry. The general block
diagram for the LM2907 is given below.
Rectenna
A rectifying antenna rectifies received microwaves into DC current. A rectenna
comprises of a mesh of dipoles and diodes for absorbing microwave energy from a transmitter
and converting it into electric power. A simple rectenna can be constructed from a Schottky
diode placed between antenna dipoles as shown in Fig.3.4. The diode rectifies the current
induced in the antenna by the microwaves. Rectenna are highly efficient at converting
microwave energy to electricity. In laboratory environments, efficiencies above 90% have
been observed with regularity. In future rectennas will be used to generate large-scale power
from microwave beams delivered from orbiting GPS satellites
Process of Rectification
Studies on various microwave power rectifier configurations show that a bridge
configuration is better than a single diode one. But the dimensions and the cost of that kind of
solution do not meet our objective. This study consists in designing and simulating a single
diode power rectifier in “hybrid technology” with improved sensitivity at low power levels.
We achieved good matching between simulation results and measurements thanks to the
optimization of the packaging of the Schottky diode.
Microwave energy transmitted from space to earth apparently has the potential to
provide environmentally clean electric power on a very large scale. The key to improve
transmission efficiency is the rectifying circuit. The aim of this study is to make a low cost
power rectifier for low and high power levels at a frequency of 2.45GHz with good efficiency
of rectifying operation. The objective also is to increase the detection sensitivity at low power
levels of power.
Different configurations can be used to convert the electromagnetic waves into DC
signal. The study done showed that the use of a bridge is better than a single diode, but the
purpose of this study is to achieve a low cost microwave rectifier with single Schottky diode
for low and high power levels that has a good performance.
CONCLUSION
Thus this paper successfully demonstrates a novel method of using the power of
microwave to charge mobile phones without use of wired chargers. It provides great
advantage to mobile phone users to carry their phones anywhere even if the place is devoid of
facilities for charging. It has effect on human beings similar to that from cell phones at
present. The use of rectenna and sensor in mobile phone could provide new dimension in the
revolution of mobile power.
[attachment=66852]
INTRODUCTION
To start with, to know what a spectrum is: when white light is shone through a prism it
is separated out into all the colors of the rainbow; this is the visible spectrum. So white light is
a mixture of all colors. Black is NOT a color; it is what you get when all the light is taken
away. Some physicists pretend that light consists of tiny particles which they call photons.
They travel at the speed of light (what a surprise). The speed of light is about 300,000,000
meters per second. When they hit something they might bounce off, go right through or get
absorbed. What happens depends a bit on how much energy they have. If they bounce off
something and then go into your eye you will "see" the thing they have bounced off. Some
things like glass and Perspex will let them go through; these materials are transparent.
Black objects absorb the photons so you should not be able to see black things: you
will have to think about this one. These poor old physicists get a little bit confused when they
try to explain why some photons go through a leaf, some are reflected, and some are
absorbed. They say that it is because they have different amounts of energy. Other physicists
pretend that light is made of waves. These physicists measure the length of the waves and this
helps them to explain what happens when light hits leaves. The light with the longest
Microwave Region
Microwave wavelengths range from approximately one millimeter (the thickness of a
pencil lead) to thirty centimeters (about twelve inches). In a microwave oven, the radio waves
generated are tuned to frequencies that can be absorbed by the food. The food absorbs the
energy and gets warmer. The dish holding the food doesn't absorb a significant amount of
energy and stays much cooler. Microwaves are emitted from the Earth, from objects such as
cars and planes, and from the atmosphere. These microwaves can be detected to give
information, such as the temperature of the object that emitted the microwaves.
Microwaves have wavelengths that can be measured in centimeters! The longer
microwaves, those closer to a foot in length, are the waves which heat our food in a
microwave oven. Microwaves are good for transmitting information from one place to
another because microwave energy can penetrate haze, light rain and snow, clouds, and
smoke. Shorter microwaves are used in remote sensing. These microwaves are used for
clouds and smoke, these waves are good for viewing the Earth from space Microwave waves
are used in the communication industry and in the kitchen as a way to cook foods. Microwave
radiation is still associated with energy levels that are usually considered harmless except for
people with pace makers.
Magnetron
Magnetron is the combination of a simple diode vacuum tube with built in cavity
resonators and an extremely powerful permanent magnet. The typical magnet consists of a
circular anode into which has been machined with an even number of resonant cavities. The
diameter of each cavity is equal to a one-half wavelength at the desired operating frequency.
The anode is usually made of copper and is connected to a high-voltage positive direct
current. In the center of the anode, called the interaction chamber, is a circular cathode.
The magnetic fields of the moving electrons interact with the strong field supplied by
the magnet. The result is that the path for the electron flow from the cathode is not directly
to the anode, but instead is curved. By properly adjusting the anode voltage and the strength
of the magnetic field, the electrons can be made to bend that they rarely reach the anode
and cause current flow. The path becomes circular loops. Eventually, the electrons do reach
the anode and cause current flow
Slotted Waveguide Antenna
The slotted waveguide is used in an omni-directional role. It is the simplest ways to
get a real 10dB gain over 360 degrees of beam width. The Slotted waveguide antenna is
a Horizontally Polarized type Antenna, light in weight and weather proof.3 Tuning screws are
placed for tweaking the SWR and can be used to adjust the centre frequency downwards from
2320MHz nominal to about 2300 MHz .This antenna is available for different frequencies.
This antenna, called a slotted waveguide, is a very low loss transmission line. It allows
propagating signals to a number of smaller antennas (slots). The signal is coupled into the
waveguide with a simple coaxial probe, and as it travels along the guide, it traverses the slots.
Each of these slots allows a little of the energy to radiate. The slots are in a linear array
pattern. The waveguide antenna transmits almost all of its energy at the horizon, usually
exactly where we want it to go. Its exceptional directivity in the elevation plane gives it quite
high power gain. Additionally, unlike vertical collinear antennas, the slotted waveguide
transmits its energy using horizontal polarization, the best type for distance transmission.
RECEIVER SECTION
The basic addition to the mobile phone is going to be the rectenna. A rectenna is a
rectifying antenna, a special type of antenna that is used to directly convert microwave
energy into DC electricity. Its elements are usually arranged in a mesh pattern, giving it a
distinct appearance from most antennae. A simple rectenna can be constructed from a
Schottky diode placed between antenna dipoles. The diode rectifies the current induced in the
antenna by the microwaves. Rectenna are highly efficient at converting microwave energy to
electricity. Some experimentation has been done with inverse rectenna, converting electricity
into microwave energy, but efficiencies are much lower--only in the area of 1%. With the
advent of nanotechnology and MEMS the size of these devices can be brought down to
molecular level. It has been theorized that similar devices, scaled down to the proportions
used in nanotechnology, could be used to convert light into electricity at much greater
efficiencies than what is currently possible with solar cells. This type of device is called an
optical rectenna. Theoretically, high efficiencies can be maintained as the device shrinks, but
experiments funded by the United States National Renewable energy Laboratory have so far
only obtained roughly 1% efficiency while using infrared light. Another important part of our
receiver circuitry is a simple sensor. This is simply used to identify when the mobile phone
user is talking. As our main objective is to charge the mobile phone with the transmitted
microwave after rectifying it by the rectenna, the sensor plays an important role. The whole
setup looks something like this.
Sensor Circuit
The sensor circuitry is a simple circuit, which detects if the mobile phone receives any
message signal. This is required, as the phone has to be charged as long as the user is talking.
Thus a simple F to V converter would serve our purpose. In India the operating frequency of
the mobile phone operators is generally 900MHz or 1800MHz for the GSM system for
mobile communication. Thus the usage of simple F to V converters would act as switches to
trigger the rectenna circuit to on.
A simple yet powerful F to V converter is LM2907. Using LM2907 would greatly
serve our purpose. It acts as a switch for triggering the rectenna circuitry. The general block
diagram for the LM2907 is given below.
Rectenna
A rectifying antenna rectifies received microwaves into DC current. A rectenna
comprises of a mesh of dipoles and diodes for absorbing microwave energy from a transmitter
and converting it into electric power. A simple rectenna can be constructed from a Schottky
diode placed between antenna dipoles as shown in Fig.3.4. The diode rectifies the current
induced in the antenna by the microwaves. Rectenna are highly efficient at converting
microwave energy to electricity. In laboratory environments, efficiencies above 90% have
been observed with regularity. In future rectennas will be used to generate large-scale power
from microwave beams delivered from orbiting GPS satellites
Process of Rectification
Studies on various microwave power rectifier configurations show that a bridge
configuration is better than a single diode one. But the dimensions and the cost of that kind of
solution do not meet our objective. This study consists in designing and simulating a single
diode power rectifier in “hybrid technology” with improved sensitivity at low power levels.
We achieved good matching between simulation results and measurements thanks to the
optimization of the packaging of the Schottky diode.
Microwave energy transmitted from space to earth apparently has the potential to
provide environmentally clean electric power on a very large scale. The key to improve
transmission efficiency is the rectifying circuit. The aim of this study is to make a low cost
power rectifier for low and high power levels at a frequency of 2.45GHz with good efficiency
of rectifying operation. The objective also is to increase the detection sensitivity at low power
levels of power.
Different configurations can be used to convert the electromagnetic waves into DC
signal. The study done showed that the use of a bridge is better than a single diode, but the
purpose of this study is to achieve a low cost microwave rectifier with single Schottky diode
for low and high power levels that has a good performance.
CONCLUSION
Thus this paper successfully demonstrates a novel method of using the power of
microwave to charge mobile phones without use of wired chargers. It provides great
advantage to mobile phone users to carry their phones anywhere even if the place is devoid of
facilities for charging. It has effect on human beings similar to that from cell phones at
present. The use of rectenna and sensor in mobile phone could provide new dimension in the
revolution of mobile power.