2. SARATH.S.KUMAR

3. INTRODUCTION
 Charging of mobile phones are becoming a problem while
travelling
 This new technology of wireless charging will be a great relief for
this
 Here mobile phones can be charged from any where ,any time
 We can charge our mobile phones by just making a call
 Charging is done by converting the microwaves reaching the
mobile phones to dc

4. MICROWAVES
 Microwaves are emitted 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.
 Shorter microwaves are used in remote sensing.
.
 Microwaves, used for radar, are just a few inches long. Because
microwaves can penetrate haze, light rain and snow, clouds and
smoke.

6.  Micro wave spectrum containing different band such
as L band, S band etc
 Here 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

7. SCHEMATIC DIAGRAM

8. TRANSMITTER DESIGN
•A magnetron is a main part of transmitter
magnetron

9. Magnetron
 The MAGNETRON is a self-contained
microwave oscillator.
 There's a heated cathode (coloured
yellow)
 A ring-shaped anode surrounds the
cathode (colored red).
 When the electrons try to zip from
cathode to anode, , they feel a force
and follow a curved path (blue circle)
 As the electrons nip past the
cavities, the cavities resonate and
emit microwave radiation

10. MAGNETRON OPERATION PHASE 1
Cathode centre at high negative volts
Anode at zero volts
No magnetic field
Electrons move in straight line
Magnet added
North pole on top
South pole at bottom
Electrons curve to the right
Electrons curve more when the magnetic field is
increased

11. MAGNETRON OPERATION PHASE 1
Green path Weak magnet. All cathode electrons reach anode
Red path Magnetic field increased to “critical” value. Anode current decreases to
a small value.
yellow path Magnetic field increased further. Anode current drops to zero
Magnetic field adjusted to where electrons just fail to reach the anode, the
magnetron can oscillate

12. MAGNETRON OPERATION PHASE 2
Interaction space between cathode and cavities
2 electric fields, ac & dc in interaction space
Polarity is one instant of ac (µ-wave) field
The dc field extends radially from cavities to cathode
Electrons near cavities move tangentially to cavities
Electrons approaching the positive sides are speeded up
Electrons departing the positive side and approaching the negative side are
slowed down.

13. MAGNETRON OPERATION PHASE 3
12 cavity magnetron 8 cavity magnetron
Rotating 6 spoke space charge 4 spoke wheel
Space charge gives µ-wave energy to the
cavity keeping it oscillating

14. MAGNETRON OPERATION PHASE 4
Assume dc field & rf fields on cavities (magnetron oscillating
Electron approaching cavity gives up energy to cavity
Electron slows down accordingly
Then electron speeds up gaining energy from dc field
Electron eventually reaches cavity (anode current)

15. RECIEVER DESIGN
 The reciever consists of
 A RECTIFYING PART
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.
 With the advent NANOTECHNOLOGY and MEMS the size of
these devices can be brought down to molecular level.
 SENSOR PART
Another important part of our receiver circuitry is a simple
sensor. This is simply used to identify when the mobile phone
user is talking.

16. Process of rectification
 AN 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
 Rectenna are highly efficient at converting microwave
energy to electricity. In laboratory
environments, efficiencies above 90% have been observed
with regularity
.
 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.

17. RECTIFYING ANTENNA
CIRCUITARY

18. Sensor circuitry
 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.
 A simple F to V converter would serve our purpose.
 Thus the usage of simple F to V converters (LM2907.)would act as
switches to trigger the rectenna circuit to on.
 It acts as a switch for triggering the rectenna circuitry.
 Thus on the reception of the signal the sensor circuitry directs the
rectenna circuit to ON and the mobile phone begins to charge using
the microwave power.

20. ADVANTAGES
 Has wide application..
 Can charge our mobile phones any where any time
even if the place is devoid of facilities for charging.
 Wired chargers can be eliminated…
 Have a wide future scope…
 Could provide a new dimension in the revelation of
mobile phone.

21. CONCLUSION
 It have great advantage of mobile phone users
 they cannot carry their chargers
 Rectenna and sensors gives new dimension in mobile
phone
 Initial cost large

22. BATTERY FULL