21-04-2011, 04:30 PM
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WIRELESS CHARGING OF MOBILE PHONES USING MICROWAVES
ABSTRACT:
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 stand by 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. In this paper 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 is 2.45 GHz. This can be achieved by adding a sensor, a Rectenna and a filter circuitry to exisisting mobile
handset design. 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.
KEYWORDS:
Magnetron
Slotted waveguide antenna
Rectenna
Sensor
INTRODUCTION:
THE ELECTROMAGNETIC SPECTRUM:
THE MICROWAVE REGION:
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.
The frequency selection is another important aspect in transmission. Here we are going to use the S band of the Microwave Spectrum, which lies between 2-4GHz.We have selected the license free 2.45 GHz ISM band for our purpose. The Industrial, Scientific and Medical (ISM) radio bands were originally reserved internationally for non-commercial use of RF electromagnetic fields for industrial, scientific and medical purposes. In recent years they have also been used for license-free error-tolerant communications applications such as wireless LANs and Bluetooth.
TRANSMITTER DESIGN:
The magnetron is called a "crossed-field" device in the industry because both magnetic and electric fields are employed in its operation, and they are produced in perpendicular directions so that they cross. The applied magnetic field is constant and applied along the axis of the circular device illustrated. The power to the device is applied to the center cathode which is heated to supply energetic electrons which would, in the absence of the magnetic field, tend to move radially outward to the ring anode which surrounds it.
Electrons are released at the center hot cathode by the process of thermionic emission and have an accelerating field which moves them outward toward the anode. The axial magnetic field exerts a magnetic force on these charges which is perpendicular to their initially radial motion, and they tend to be swept around the circle. In this way, work is done on the charges and therefore energy from the power supply is given to them. As these electrons sweep toward a point where there is excess negative charge, that charge tends to be pushed back around the cavity, imparting energy to the oscillation at the natural frequency of the cavity. This driven oscillation of the charges around the cavities leads to radiation of electromagnetic waves, the output of the magnetron.
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. Rectennae are highly efficient at converting microwave energy to electricity. In laboratory environments, efficiencies above 90% have been observed with regularity.
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.
THE SLOTTED WAVEGUIDE ANTENNA:
A slotted waveguide is a waveguide that is used as an antenna in microwave radar applications. Prior to its use in surface search radar, such systems used a parabolic segment reflector. The circulator is connected to a tuning waveguide section to match the waveguide impedance to the antenna input impedance.
The slotted waveguide antenna consists of 8 waveguide sections with 8 slots on each section. These 64 slots radiate the power uniformly through free space to the rectenna. The slotted waveguide antenna is ideal for power transmission because of its high aperture efficiency (> 95%) and high power handling capability.
RECTENNA:
A rectifying antenna called a rectenna receives the transmitted power and converts the microwave power to direct current (DC) power. This demonstration rectenna consists of 6 rows of dipoles antennas where 8 dipoles belong to each row. Each row is connected to a rectifying circuit which consists of low pass filters and a rectifier. The rectifier is a GaAs Schottky barrier diode that is impedance matched to the dipoles by a low pass filter. The diode rectifies the current induced in the antenna by the microwaves.
WIRELESS CHARGING OF MOBILE PHONES USING MICROWAVES
ABSTRACT:
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 stand by 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. In this paper 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 is 2.45 GHz. This can be achieved by adding a sensor, a Rectenna and a filter circuitry to exisisting mobile
handset design. 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.
KEYWORDS:
Magnetron
Slotted waveguide antenna
Rectenna
Sensor
INTRODUCTION:
THE ELECTROMAGNETIC SPECTRUM:
THE MICROWAVE REGION:
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.
The frequency selection is another important aspect in transmission. Here we are going to use the S band of the Microwave Spectrum, which lies between 2-4GHz.We have selected the license free 2.45 GHz ISM band for our purpose. The Industrial, Scientific and Medical (ISM) radio bands were originally reserved internationally for non-commercial use of RF electromagnetic fields for industrial, scientific and medical purposes. In recent years they have also been used for license-free error-tolerant communications applications such as wireless LANs and Bluetooth.
TRANSMITTER DESIGN:
The magnetron is called a "crossed-field" device in the industry because both magnetic and electric fields are employed in its operation, and they are produced in perpendicular directions so that they cross. The applied magnetic field is constant and applied along the axis of the circular device illustrated. The power to the device is applied to the center cathode which is heated to supply energetic electrons which would, in the absence of the magnetic field, tend to move radially outward to the ring anode which surrounds it.
Electrons are released at the center hot cathode by the process of thermionic emission and have an accelerating field which moves them outward toward the anode. The axial magnetic field exerts a magnetic force on these charges which is perpendicular to their initially radial motion, and they tend to be swept around the circle. In this way, work is done on the charges and therefore energy from the power supply is given to them. As these electrons sweep toward a point where there is excess negative charge, that charge tends to be pushed back around the cavity, imparting energy to the oscillation at the natural frequency of the cavity. This driven oscillation of the charges around the cavities leads to radiation of electromagnetic waves, the output of the magnetron.
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. Rectennae are highly efficient at converting microwave energy to electricity. In laboratory environments, efficiencies above 90% have been observed with regularity.
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.
THE SLOTTED WAVEGUIDE ANTENNA:
A slotted waveguide is a waveguide that is used as an antenna in microwave radar applications. Prior to its use in surface search radar, such systems used a parabolic segment reflector. The circulator is connected to a tuning waveguide section to match the waveguide impedance to the antenna input impedance.
The slotted waveguide antenna consists of 8 waveguide sections with 8 slots on each section. These 64 slots radiate the power uniformly through free space to the rectenna. The slotted waveguide antenna is ideal for power transmission because of its high aperture efficiency (> 95%) and high power handling capability.
RECTENNA:
A rectifying antenna called a rectenna receives the transmitted power and converts the microwave power to direct current (DC) power. This demonstration rectenna consists of 6 rows of dipoles antennas where 8 dipoles belong to each row. Each row is connected to a rectifying circuit which consists of low pass filters and a rectifier. The rectifier is a GaAs Schottky barrier diode that is impedance matched to the dipoles by a low pass filter. The diode rectifies the current induced in the antenna by the microwaves.
