Wireless Charging Of mobile phones Seminar Report

34
WIRELESS CHARGING OF MOBILE PHONES USING MICROWAVES 1. INTRODUTION With mobile phones becoming a basic part of life, the recharging of mobile phone batteries has always been a problem. The mobile phones vary in their talk time and battery standby according to their manufacturer and batteries. All these phones irrespective of their manufacturer and batteries have to be put to recharge after the battery has drained out. The main objective of this current proposal is to make the recharging of the mobile phones independent of their manufacturer and battery make. A new proposal has been made so as to make the recharging of the mobile phones is done automatically as you talk in your mobile phone. This is done by use of microwaves. The microwave signal is transmitted from the transmitter along with the message signal using special kind of antennas called slotted wave guide antenna at a frequency 2.45 GHz. There are minimal additions, which have to be made in the mobile handsets, which are the addition of a sensor, a ‘rectenna’, and a ‘filter’. With the above setup, the need for separate chargers for mobile phones is eliminated and makes charging universal. Thus the more you talk, the more your mobile phone will be charged. Electronics & Communication Engineering, BBDESGI 1

description

With mobile phones becoming a basic part of life, the recharging of mobile phone batteries has always been a problem. The mobile phones vary in their talk time and battery standby according to their manufacturer and batteries. All these phones irrespective of their manufacturer and batteries have to be put to recharge after the battery has drained out. The main objective of this current proposal is to make the recharging of the mobile phones independent of their manufacturer and battery make.A new proposal has been made so as to make the recharging of the mobile phones is done automatically as you talk in your mobile phone. This is done by use of microwaves. The microwave signal is transmitted from the transmitter along with the message signal using special kind of antennas called slotted wave guide antenna at a frequency 2.45 GHz. There are minimal additions, which have to be made in the mobile handsets, which are the addition of a sensor, a ‘rectenna’, and a ‘filter’. With the above setup, the need for separate chargers for mobile phones is eliminated and makes charging universal. Thus the more you talk, the more your mobile phone will be charged. With this proposal the manufacturers would be able to remove the talk time and battery standby from their phone specifications.Thus this seminar successfully demonstrates a novel method of using the power of the microwave to charge the mobile phones without the use of wired chargers. Thus this method provides great advantage to the mobile phone users to carry their phones anywhere even if the place is devoid of facilities for charging. A novel use of the rectenna and a sensor in a mobile phone could provide a new dimension in the revelation of mobile phone.

Transcript of Wireless Charging Of mobile phones Seminar Report

Page 1: Wireless Charging Of mobile phones Seminar Report

WIRELESS CHARGING OF MOBILE PHONES USING MICROWAVES

1. INTRODUTION

With mobile phones becoming a basic part of life, the recharging of mobile

phone batteries has always been a problem. The mobile phones vary in their talk time

and battery standby according to their manufacturer and batteries. All these phones

irrespective of their manufacturer and batteries have to be put to recharge after the

battery has drained out. The main objective of this current proposal is to make the

recharging of the mobile phones independent of their manufacturer and battery make.

A new proposal has been made so as to make the recharging of the mobile

phones is done automatically as you talk in your mobile phone. This is done by use of

microwaves. The microwave signal is transmitted from the transmitter along with the

message signal using special kind of antennas called slotted wave guide antenna at a

frequency 2.45 GHz.

There are minimal additions, which have to be made in the mobile handsets,

which are the addition of a sensor, a ‘rectenna’, and a ‘filter’. With the above setup,

the need for separate chargers for mobile phones is eliminated and makes charging

universal. Thus the more you talk, the more your mobile phone will be charged. With

this proposal the manufacturers would be able to remove the talk time and battery

standby from their phone specifications.

Thus this seminar successfully demonstrates a novel method of using the power

of the microwave to charge the mobile phones without the use of wired chargers.

Thus this method provides great advantage to the mobile phone users to carry their

phones anywhere even if the place is devoid of facilities for charging. A novel use of

the rectenna and a sensor in a mobile phone could provide a new dimension in the

revelation of mobile phone.

Electronics & Communication Engineering, BBDESGI1

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1.1 The Electromagnetic spectrum

Spectrum results, when a white light is pass through a prism it is separated out

into all the colours of the rainbow. This is the visible spectrum. So white light is a

mixture of all colours .

Some physicists pretend that light consists of tiny particles which they call

photons. They travel at the speed of light. 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 is depends on a bit and how much energy they have.

If they bounce off something and then go into eye will cause to see the things 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 it results not be able to

see black things. This is the problem has to be sorted out. 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

and leaves. The light with the longest wavelength (red) is absorbed by the green stuff

(chlorophyll) in the leaves. There is green light, this is allowed to pass right through

or is reflected. (Indigo and violet have shorter wavelengths than blue light.)

It is easy to explain some of the properties of light by pretending that it is

made of tiny particles called photons and it is easy to explain other properties of light

by pretending that it is some kind of wave.

The visible spectrum is just one small part of the electromagnetic spectrum.

These electromagnetic waves are made up of two parts. The first part is an electric

field. The second part is a magnetic field. So they are called as electromagnetic

waves. The two fields are at right angles to each other. The Various other parts of the

emf spectrum and their location can be seen diagrammatically as shown below.

Electronics & Communication Engineering, BBDESGI2

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1.2 Electromagnetic waves

Electromagnetic waves can be imagined as a self-propagating transverse

oscillating wave of electric and magnetic fields. This diagram shows a plane linearly

polarised wave propagating from left to right. An electromagnetic wave is a wave in

space with electric and magnetic parts.

Electromagnetic radiation is classified into types according to the frequency of

the wave. These types include, in order of increasing frequency, radio waves,

microwaves, terahertz radiation, infrared radiation, visible light, ultraviolet radiation,

X-rays and gamma rays. In some technical contexts the entire range is referred to as

just light.

Fig 1: An EM wave

Microwaves are electromagnetic waves with wavelengths ranging from as

long as one meter to as short as one millimeter, or equivalently, with frequencies

between 300 MHz (0.3 GHz) and 300 GHz as shown in the Fig 1. This broad

definition includes both UHF and EHF (millimeter waves), and various sources use

different boundaries. In all cases, microwave includes the entire SHF band (3 to 30

GHz, or 10 to 1 cm) at minimum, with RF. Engineering often putting the lower

boundary at 1 GHz (30 cm), and the upper around 100 GHz (3mm).

Electronics & Communication Engineering, BBDESGI3

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Apparatus and techniques may be described qualitatively as "microwave" when

the wavelengths of signals are roughly the same as the dimensions of the equipment,

so that lumped element circuit theory is inaccurate. As a consequence, practical

microwave technique tends to move away from the discrete resistors, capacitors, and

inductors used with lower frequency radio waves. Instead, distributed circuit elements

and transmission-line theory are more useful methods for design and analysis.

Fig 2: Lumped element circuit

Open-wire and coaxial transmission lines give way to waveguides and stripline,

and lumped-element tuned circuits as shown in the Fig 2 are replaced by cavity

resonators or resonant lines. Effects of reflection, polarization, scattering, diffraction

and atmospheric absorption usually associated with visible light are of practical

significance in the study of microwave propagation. The same equations of

electromagnetic theory apply at all frequencies.

Electronics & Communication Engineering, BBDESGI4

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While the name may suggest a micrometer wavelength, it is better understood as

indicating wavelengths very much smaller than those used in radio broadcasting. The

boundaries between far infrared light, terahertz radiation, microwaves, and ultra-high

frequency radio waves are fairly arbitrary and are used variously between different

fields of study.

1.3 Need and processing of micro waves

EM wave posses some kind of energy with it. This repots explains about the

usage of this valuable energy for recharging of mobile phones, becoming a basic part

of life, to avoid the problem of charging the mobile phone batteries without

electricity.

The mobile phones vary in their talk time and battery standby according to

their manufacturer and batteries. All these phones irrespective of their manufacturer

and batteries have to be put to recharge after the battery has drained out. In this aspect

a new proposal has been made so as to make the recharging of the mobile phones is

done automatically while using the mobile phone. This is done by use of microwaves.

The microwave signal is transmitted from the transmitter along with the message

signal using special kind of antennas called slotted wave guide antenna at a frequency

is 2.45GHz.

With minimal additions, which have to be made in the mobile handsets, which

are the addition of a sensor, a rectenna and a filter. With the above setup, the need for

separate chargers for mobile phones is eliminated and makes charging universal. Thus

the more you talk, the more is your mobile phone charged . With this proposal the

manufacturers would be able to remove the talk time and battery standby from their

phone specifications.

EM wave posses some kind of energy with it. This repots explains about the

usage of this valuable energy for recharging of mobile phones, becoming a basic part

Electronics & Communication Engineering, BBDESGI5

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of life, to avoid the problem of charging the mobile phone batteries without

electricity.

2. Wireless charging

Wireless charging is any of several methods of charging batteries without the

use of cables or device-specific AC adaptors. Wireless charging can be used for a

wide variety of devices including cell phones, laptop computers and MP3 players as

well as larger objects, such as robots and electric cars.

2.1 Different types of wireless charging

There are three methods of wireless charging:

Inductive charging,

radio charging

Resonance charging.

2.2 Inductive charging

It is used for charging mid-sized items such as cell phones, MP3 players and

PDAs. In inductive charging, an adapter equipped with contact points is attached to

the device's back plate. When the device requires a charge, it is placed on a

conductive charging pad, which is plugged into a socket.

2.2.1 Advantages

Inductive charging carries a far lower risk of electrical shock, when compared

with conductive charging, because there are no exposed conductors. The ability to

fully enclose the charging connection also makes the approach attractive where water

impermeability is required; for instance, inductive charging is used for implanted

medical devices that require periodic or even constant external power, and for electric

hygiene devices, such as toothbrushes and shavers, that are frequently used near or

even in water. Inductive charging makes charging mobile devices more convenient;

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rather than having to connect a power cable, the device can be placed on a charge

plate.

2.2.2 Disadvantages

One disadvantage of inductive charging is its lower efficiency and increased

ohmic (resistive) heating in comparison to direct contact. Implementations using

lower frequencies or older drive technologies charge more slowly and generate heat

for most portable electronics, [excitation needed] the technology-is nonetheless

commonly used in some electric toothbrushes and wet/dry electric shavers, partly for

the advantage that the battery contacts can be completely sealed to prevent exposure

to water. Inductive charging also requires drive electronics and coils that increase

manufacturing complexity and cost.

2.3 Radio charging

It is used for charging items with small batteries and low power requirements,

such as watches, hearing aids, medical implants, cell phones, MP3 players and

wireless keyboard and mice. Radio waves are already in use to transmit and receive

cellular telephone, television, radio and Wi-Fi signals. Wireless radio charging works

similarly. A transmitter, plugged into a socket, generates radio waves. When the

receiver attached to the device is set to the same frequency as the transmitter, it will

charge the device's battery.

2.4 Resonance charging

It is used for items that require large amounts of power, such as an electric car,

robot, vacuum cleaner or laptop computer. In resonance charging, a copper coil

attached to a power source is the sending unit. Another coil, attached to the device to

be charged, is the receiver. Both coils are tuned to the same electromagnetic

frequency, which makes it possible for energy to be transferred from one to the other.

The method works over short distances (3-5 meters).

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The idea of wireless power transmission is not new. In 1899, Nikola Tesla

wirelessly transmitted 100 million volts of electricity 26 miles to light 200 bulbs and

run an electric motor.

3. Microwave Region

3.1 Microwave frequency bands

Designation Frequency range

L Band l to 2 GHz

S Band 2 to 4 GHz

C Band 4 to 8 GHz

X Band 8 to 12 GHz

K11 Band 12 to 18 GHz

K Band 18 to 26 GHz

Ka Band 26 to 40 GHz.

Q Band 30 to 50 GHz

U Band 40 to 60 GHz

V Band 46 to 56 GHz

W Band 56 to 100 GHz

The S band of the Microwave Spectrum is useful for wireless charging.

3.2 Properties of microwave links

Involve line of sight (LOS) communication technology.

Affected greatly by environmental constraints, including rain fade.

Have limited penetration capabilities.

Sensitive to high pollen count.

Signals can be degraded during Solar proton event.

Electronics & Communication Engineering, BBDESGI8

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3.3 Electro Magnetic Spectrum

Fig 3: Electromagnetic spectrum

Electronics & Communication Engineering, BBDESGI9

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The electromagnetic spectrum as shown in the Fig 3 is the range of all

possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of

an object is the characteristic distribution of electromagnetic radiation emitted or

absorbed by that particular object.

The electromagnetic spectrum extends from low frequencies used for modern

radio to gamma radiation at the short-wavelength end, covering wavelengths from

thousands of kilometers down to a fraction of the size of an atom. The

long wavelength limit is the size of the universe itself, while it is thought that the

short wavelength limit is in the vicinity of the Planck length, although in principle the

spectrum is infinite and continuous.

Some physicists pretend that light consists of tiny particles which they call

photons. They travel at the speed of light. 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 is depends on a bit and how much energy they have.

If they bounce off something and then go into eye will cause to see the things 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 it results not be able to

see black things. This is the problem has to be sorted out. 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

and leaves. The light with the longest wavelength (red) is absorbed by the green stuff

(chlorophyll) in the leaves. There is green light, this is allowed to pass right through

or is reflected. (Indigo and violet have shorter wavelengths than blue light.)

It is easy to explain some of the properties of light by pretending that it is

made of tiny particles called photons and it is easy to explain other properties of light

by pretending that it is some kind of wave.

Electronics & Communication Engineering, BBDESGI10

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The visible spectrum is just one small part of the electromagnetic spectrum.

These electromagnetic waves are made up of two parts. The first part is an electric

field. The second part is a magnetic field. So they are called as electromagnetic

waves. The two fields are at right angles to each other.

4. Transmitter Design

The Magnetron is a self-contained microwave oscillator that operates

differently from the linear-beam tubes, such as the TWT and the klystron CROSSED-

ELECTRON and MAGNETIC fields are used in the magnetron to produce the high-

power output required in radar and communications equipment.

The magnetron is classed as a diode because it has no grid. A magnetic field

located in the space between the plate (anode) and the cathode serves as a grid. The

plate of a magnetron does not have the same physical appearance as the plate of an

ordinary electron tube. Since conventional inductive-capacitive (LC) networks

become impractical at microwave frequencies, the plate is fabricated into a cylindrical

copper block containing resonant cavities that serve as tuned circuits. The magnetron

base differs considerably from the conventional tube base. The magnetron base is

short in length and has large diameter leads that are carefully.

The cathode and filament are at the center of the tube and are supported by the

filament leads. The filament leads are large and rigid enough to keep the cathode and

filament structure fixed in position. The output lead is usually a probe or loop

extending into one of the tuned cavities and coupled into a waveguide or coaxial line.

The plate structure, shown in Fig 4 is a solid block of copper.

The cylindrical holes around its circumference are resonant cavities. A narrow

slot runs from each cavity into the central portion of the tube dividing the inner

structure into as many segments as there are cavities. Alternate segments are strapped

together to put the cavities in parallel with regard to the output. The cavities control

the output frequency.

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The straps are circular, metal bands that are placed across the top of the block

at the entrance slots to the cavities. Since the cathode must operate at high power, it

must be fairly large and must also be able to withstand high operating temperatures. It

must also have good emission characteristics, particularly under return bombardment

by the electrons. This is because most of the output power is provided by the large

number of electrons that are emitted when high-velocity electrons return to strike the

cathode. The cathode is indirectly heated and is constructed of a high-emission

material. The open space between the plate and the cathode is called the

INTERACTION SPACE. In this space the electric and magnetic fields interact to

exert force upon the electrons.

Fig 4: Transmitter Design

The plate structure, shown in Fig 4 is a solid block of copper. The cylindrical

holes around its circumference are resonant cavities. A narrow slot runs from each

cavity into the central portion of the tube dividing the inner structure into as many

segments as there are cavities. Alternate segments are strapped together to put the

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cavities in parallel with regard to the output. The cavities control the output

frequency.

The cathode and filament are at the center of the tube and are supported by the

filament leads. The filament leads are large and rigid enough to keep the cathode and

filament structure fixed in position. The output lead is usually a probe or loop

extending into one of the tuned cavities and coupled into a wave guide or coaxial line.

5. Receiver Design

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. In' laboratory environments, efficiencies above 90% have been observed

with regularity.

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

Electronics & Communication Engineering, BBDESGI13

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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.

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.

5.1 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.

The cathode and filament are at the center of the tube- and are supported by

the filament leads. The filament leads are large and rigid enough to keep the cathode

and filament structure fixed in position. The output lead is usually a probe or loops

extending into one of the tuned cavities and coupled into a waveguide or coaxial line.

The plate structure, is a solid block of copper. The cylindrical holes around its

circumference are resonant cavities. A narrow slot runs from each cavity into the

central portion of the tube dividing the inner structure into as many segments as there

are cavities. Alternate segments are strapped together to put the cavities in parallel

with regard to the output. The cavities control the output frequency. The straps are

circular, metal bands that are placed across the top of the block at the entrance slots to

Electronics & Communication Engineering, BBDESGI14

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the cavities. Since the cathode must operate at high power, it must be fairly large and

must also be able to withstand high operating temperatures.

It must also have good emission characteristics, particularly under return

bombardment by the electrons. This is because most of the output power is provided

by the large number of electrons that are emitted when high-velocity electrons return

to strike the cathode.

The cathode is indirectly heated and is constructed of a high-emission

material. The open space between the plate and the cathode is called the INTERAC

TION SPACE. In this space the electric and magnetic fields interact to exert force

upon the electrons. Arranged in a mesh pattern, giving it a distinct appearance from

most antenna. 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. In

laboratory environments, efficiencies above 90% have been observed with regularity.

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.

Electronics & Communication Engineering, BBDESGI15

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A Schottky barrier diode is different from a common P/N silicon diode. The

common diode is formed by connecting a P type semiconductor with an N type

semiconductor, this is connecting between a semiconductor and another

semiconductor; however, a Schottky barrier diode is formed by connecting a metal

with a semiconductor. When the metal contacts the semiconductor, there will be a

layer of potential barrier (Schottky barrier) formed on the contact surface of them,

which shows a characteristic of rectification. The material of the semiconductor

usually is a semiconductor of n-type (occasionally p-type), and the material of metal

generally is chosen from different metals such as molybdenum, chromium, platinum

and tungsten. Sputtering technique connects the metal and the semiconductor.

A Schottky barrier diode is a majority carrier device, while a common diode is a

minority carrier device. When a common PN diode is turned from electric connecting

to circuit breakage, the redundant minority carrier on the contact surface should be

removed to result in time delay. The Schottky barrier diode itself has no minority

carrier, it can quickly turn from electric connecting to circuit breakage, its speed is

much faster than a common P/N diode, so its reverse recovery time Trr is very short

and shorter than 10 nS. And the forward voltage bias of the Schottky barrier diode is

under 0.6V or so, lower than that of the common PN diode. So, The Schottky barrier

diode is a comparatively ideal diode, such as for a 1 ampere limited current PN

interface.

Frequency of 2.45GHz with good efficiency of rectifying operation. The

objective also is to increase the detection sensitivity at low levels of power. Different

configurations can be used to convert the electromagnetic wave into DC signal, the

study done in 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 performances. This study is

divided on two kinds of technologies the first is the hybrid technology and the second

is the monolithic one. The goal of this investigation is the development of a hybrid

microwave rectifier with single Schottky diode.

Electronics & Communication Engineering, BBDESGI16

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The first study of this circuit is based on the optimization of the rectifier in order

to have a good matching of the Input impedance at the desired frequency 2.45GHz.

Besides, the aim of the second study is the increasing of the detection sensitivity at

low levels of power.

This study is divided on two kinds of technologies the first is the hybrid

technology and the second is the monolithic one. The goal of this investigation is the

development of a hybrid microwave rectifier with single Schottky diode. The first

study of this circuit is based on the optimization of the rectifier in order to have a

good matching of the input impedance the desired frequency 2.45GHz.

5.2 Antenna Design

The characteristics of an antenna, i.e. Impedance, gain and polarization depend

on the shape of antenna, with the dimensions normalized to the free-space

wavelength.

Spirals are supported to have a nearly frequency independent behavior

between a certain lower and upper frequency, given by the finite size and feed size

respectively. An ideal self-complementary antenna of infinite dimensions has a

theoretical impedance of Zspiral at the feed point and the large bandwidth, no

matching section is used.

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Fig 5: Antenna Design

Design of single spiral antenna. Layout of the 8x8 array with 64 diodes (black

devices). In the Fig 5 of single spiral antenna there is diode at centre of antenna which

converts microwave energy to Dc power. From which it can be used to charge cell

phone.

5.3 Sensor circuitry

The sensor circuitry is a simple circuit as shown in the Fig 6, 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 Y converter would act as switches to trigger the rectenna circuit

to on.

Fig 6: Sensor circuitry

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 LM2097 is given below

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Thus on the reception of the signal the sensor circuitry directs the rectenna

circuit to ON and the mobile phone begins to change using the microwave power.

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5.4 Advantages

The main advantage of Sensor circuitry is Reduce the usage of

high electricity.

Make the recharging of the mobile phones independent of their manufacturer.

Make use of valuable EM energy.

If Sensor circuitry is Very small circuitry in size.

More economical than wired charging.

Electronics & Communication Engineering, BBDESGI20

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WIRELESS CHARGING OF MOBILE PHONES USING MICROWAVES

6. Conclusion

With mobile phones becoming a basic part of life, the recharging of mobile

phone batteries has always been a problem. The mobile phones vary in their talk time

and battery standby according to their manufacturer and batteries. All these phones

irrespective of their manufacturer and batteries have to be put to recharge after the

battery has drained out. The main objective of this current proposal is to make the

recharging of the mobile phones independent of their manufacturer and battery make.

A new proposal has been made so as to make the recharging of the mobile

phones is done automatically as you talk in your mobile phone. This is done by use of

microwaves. The microwave signal is transmitted from the transmitter along with the

message signal using special kind of antennas called slotted wave guide antenna at a

frequency 2.45 GHz.

Thus this seminar successfully demonstrates a novel method of using the power

of the microwave to charge the mobile phones without the use of wired chargers.

Thus this method provides great advantage to the mobile phone users to carry their

phones anywhere even if the place is devoid of facilities for charging. A novel use of

the rectenna and a sensor in a mobile phone could provide a new dimension in the

revelation of mobile phone.

Wireless charging of mobile phones using Electromagnetic waves can reduce

the problem of electricity and will be helpful for automatic recharging of mobile

phones, which is very much useful in the future

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Electronics & Communication Engineering, BBDESGI22