Wireless Charging ppt

1
WIRELESS MOBILE CHARGING USING MICROWAVES
Kartik N. Kalpande.
2
INTRODUCTION
1. What is a spectrum? Ans 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 . The speed of light is about
300,000,000 m/s.
The visible spectrum is just one small part of
the electromagnetic spectrum. These
electromagnetic waves are made up of to two
parts. The first part is an electric field and
the second part is a magnetic field. So that is
why they are called electromagnetic waves. The
two fields are at right angles to each other.
The "electromagnetic spectrum" of an object
has a different meaning, and is instead the
characteristic distribution of electromagnetic
radiation emitted or absorbed by that particular
object. The electromagnetic spectrum extends from
below the low frequencies used for modern radio
communication to gamma radiation at the
short-wavelength (high-frequency) end, thereby
covering wavelengths from thousands of kilometres
down to a fraction of the size of an atom.

3
Most parts of the electromagnetic spectrum are
used in science for spectroscopic and other
probing interactions, as ways to study and
characterize matter. In addition, radiation
from various parts of the spectrum has found many
other uses for communications and manufacturing
The types of electromagnetic radiation are
broadly classified into the following classes
1. Gamma radiation , 2. X-ray radiation
, 3. Ultraviolet radiation , 4. Visible
radiation , 5. Infrared radiation , 6.
Microwave radiation and 7. Radio waves .
4
Fig.1.1. Electromagnetic Spectrum
5
Microwave Region Microwave wavelengths
range from approximately one millimeter to thirty
centimeters (about twelve inches).
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.
6
Fig.1.2 Microwave region of electromagnetic
spectrum
Table 1.1 Microwave spectrum
7
2. TRANSMITTER SECTION

• The transmitter section consists of two parts.
  They are
• Magnetron
• Slotted waveguide antenna

2.1 Magnetron
Magnetron is the combination of a simple diode
vacuum tube with built in cavity resonators and
an extremely powerful permanent magnet.
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.
A magnetron, therefore, is an oscillator, not an
amplifier. A takeoff loop in one cavity provides
the output
8
Fig.2.1 Magnetron
Fig 2.2 Slotted waveguide antenna
9
2.2 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.
10
3. 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.
Fig 3.1.Block Diagram
11
3.1 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.
Fig. 3.2 Block diagram for the LM2907
Fig. 3.3 LM2907 IC
12
3.2 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.
This study is divided on two kinds of
technologies. The first is the hybrid technology
and the second is the monolithic one.
Fig 3.5 Rectenna Array
Fig 3.4 Rectification
13

• 4. ADVANTAGES
• Charging of mobile phone is done wirelessly.
• We can saving time for charging mobiles.
• Wastage of power is less.
• Better than witricity as the distance the
  witricity can cover is about 20 meters whereas in
  this technology we are using base station for
  transmission that can cover more area.
• Mobile get charged as we make call even during
  long journey.

14

• 5. DISADVANTAGES
• Radiation problems may occur.
• Network traffic may cause problems in charging.
• Charging depends on network coverage.
• Rate of charging may be of minute range.

15
6. APPLICATIONS As the topics name itself
this technology is used for Wireless charging
of mobile phones.
Fig.6.1.Mobile getting charged from mobile
tower
16
7. 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.
17
THANK YOU
For any mistakes and suggestions feel free to
text here idamakanti.jaswanth_at_gmail.com