3. INTRODUCTION
The concept of transferring power without wires, however, has been around since the late
1890s. It was Nikola Tesla who dreamed of eliminating the need of wires for charging
devices or powering devices.
He was able to light electric bulbs wirelessly at his Colorado Springs Lab using
electrodynamic induction (resonant inductive coupling).
The thing which is important for this technology are the microwaves which are being
applied in various other fields .
A mobile user while having conversations sends along with the message signals ,the
microwaves from transmitter using an antenna to the receiver using rectenna .
At the receiving end these signal charges the receiver in charging his/her mobile phone
without the need for cords or charging wires .
4. ELECTROMAGNETIC SPECTRUM
To charge mobile phones microwaves play a great
role which is part of the electromagnetic spectrum.
The electromagnetic spectrum which is the
collection of energies, has been used here for even
broader applications.
The microwave region is one of the seven regions of
electromagnetic (EM spectrum ) is used for this
purpose which falls in the range of the EM spectrum
between radio waves and infrared waves.
Microwaves are good for transmitting information
from one place to another because microwave
energy can penetrate haze, light rain and snow,
clouds, and smoke.
5. MICROWAVE REGION
Microwaves are Radio wave which has a wavelength range of 1 cm
to 1 meter. And the frequency is 300MHz to 300GHz.Each and every
object on the earth absorb a different amount of microwave energy.
Microwave oven converts this microwave energy into the frequency
which the food absorbs and gets energy from it and gets the worm.
But the bowl containing the food does not get a worm because its
capacity of absorbing microwave frequency is different! Microwaves
are good at carrying information from one place to other.
As the microwave penetrates the solid material and also it does not
have an effect on weather and rain etc. So it is useful to carry
information.
There are different frequency bands according to the range of frequencies
shown:
Designation frequency range
L Band 1 to 2 GHz
S-Band 2 to 4 GHz
C Band 4 to 8 GHz
X Band 8 to 12 GHz
Ku 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 100GHz
6. DESIGN
Here as we can see there are two-part. One is the transmitting part and the
other is the Receiving part.
At the transmitting end there is one microwave power source that is
actually producing microwaves.
To help these microwaves to reach the destination or receiving end, at the
transmitter side we use a waveguide antenna which is a kind of funnel that
helps to beam out the waves into the air.
At receiving end we need a sensor that detects the presence of message
signals i.e. while a subscriber is having conversations. The role-playing
component at the receiving end is the rectenna which is the term used for
both the rectifier and the antenna.
The important work done by a rectenna is to convert the current induced by
the microwaves in the antenna to direct current (DC).
7. TRANSMITTER SECTION
A magnetron is a diode vacuum tube. The filament in
the tube act as the cathode.
Magnetron is actually acted as an oscillator to produce
microwaves. It can be done by putting a magnet
between the resonating chambers which is the center
of the oscillator. These resonating chambers are called
the anode of the magnetron.
When electrons come out from the cathode direct
towards the Anode.
As it passes through the magnetic field it starts
circulating in the resonating cavity and starts
producing waves according to its frequency. And the
generated RF signal flow outside of the chamber
8. RECEIVER SECTION
The receiver side consists of a sensor and a rectenna.
Normally, the receiver is arranged in a mesh format.
The sensor is usually used to sense the signal. The main aim of this project is to create
wireless charging whenever the receiver receives the signal.
Here, the sensor detects whether the phone receiving the microwaves or not. Another
important part of the receiver is the rectenna.
The rectenna is a combination of rectifiers and antenna which is used to convert the
microwave signal into DC power. Rectennas are very powerful to convert microwave
energy into electric power and simply they can be constructed by using a Schottky diode.
Typically, nano-technology is used to reduce the size of rectenna
9. SENSOR CIRCUIT
The sensor circuit is used to find whether the mobile phone using the microwaves
for message transferring or not!
So here we can use any Frequency to Voltage converter to do our job. Here in
India, the operating frequency of the GSM is 900 MHz to 1800 MHz We can use
LM2907 for F to V conversion.
It actually acts as a switch to trigger out the rectenna circuit on or off. So when
our phone is receiving microwave signal it makes the rectenna circuit on and
charges the battery
10. ADVANTAGES
Wireless networks are more advantageous than
cumbersome wiry networks.
Risk of electrical shocks is no more possible.
Different types of chargers with different productions can
be totally eliminated.
11. DISADVANTAGES
As the transmitter and receiver networks should be more
powerful otherwise the charging is very slow.
Initial implementation cost is high.
12. CONCLUSION
Thus this ppt successfully demonstrates a novel method of using
the power of the microwave to charge mobile phones without the
use of wired chargers.
Thus this method provides a 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 the mobile phone.
