This document proposes wirelessly charging mobile phones using microwaves transmitted from a transmitter. A rectenna and filter would be added to phones to convert microwave energy from a 2.45 GHz signal into electrical current to charge the battery. The system would allow phones to charge automatically as users talk without needing physical connections or being dependent on manufacturer or battery type. It describes the transmitter, slotted waveguide antenna, receiver design including the rectenna, sensor circuitry, and principle of operation where microwaves carrying a message signal would be received and converted to DC power by the rectenna to charge the phone. Potential implementations and advantages like remote charging and electricity savings are discussed alongside challenges like dependence on network coverage and slow charging rates.

1. WIRELESS CHARGING OF
MOBILES USING MICRO WAVES

2. INTRODUCTION
A new proposal has made recharging of the mobile phones is done
automatically as you talk in your mobile phone!
The recharging of the mobile phones is independent of their manufacturer and
battery make.
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.

3. OBJECTIVE
The main objective of this current proposal is to make the
recharging of Mobile phones independent of their manufacturer
and battery.
A rectenna & a filter is added to the ordinary mobiles during
manufacturing time….
Thus the more you talk, the more is your mobile phone charged!!!

4. WHAT IS “SPECTRUM” ???
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.

5. The visible spectrum is just one small part of the electromagnetic spectrum.
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 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
7. Radio wave radiation

6. MICROWAVE REGION
Microwave wavelength range
approximately from 1mm (thickness
of pencil lead) to 30cm (about 12
inches).
The microwave region in
electromagnetic spectrum ranges
from
0.3cm to 300cm.
Microwave region give the
information about the temperature
of the object that emitted
microwaves.

7. WHY WIRELESS CHARGING USING
MICROWAVES ?????
Microwaves are good for transmitting information
from one place to another ( because it penetrate
haze , light rain , snow , clouds etc…).
It has shorter wavelength than remote sensing.
Microwave radiation are considered harmless
except for people with pace makers.

8. FREQUENCY SELECTION
The frequency selection is another
important aspect in transmission. Here we
have selected the license free 2.45 GHz
ISM(Industrial, Scientific and Medical)
band for this purpose.
Here we are going to use the S BAND of
the Microwave spectrum.

9. TRANSMITTER DESIGN
MAGNETRON
The MAGNETRON is a self-
contained microwave oscillator that
operates differently from the linear-
beam tubes.
Cross field and magnetic field are
used to produce high-power output.
ELECTRON
BEAM ENERGY
MICROWAVE
ENERGY

10. SLOTTED WAVEGUIDE ANTENNA
It is used as ideal power transmitter
(because of its high aperture efficiency
>95%) .
High impedance matching
It has 64 slots of power uniformly
through free space to the RECTENNA.
The slotted waveguide transmits its
energy using horizontal polarization, the
best type for distanace transmission.

11. RECEIVER DESIGN
The basic addition to a mobile phone is to be RECTENNA.
RECTENNA is a rectifying antenna, a special type of antenna that is used to
convert microwave energy into direct current electricity.
Its elements are usually arranged in a mesh pattern .
Antenna is to receive the microwave signal and it just feed the signal to rectifier .
Rectifier is to convert the microwave energy to electricity.

12. SENSOR CIRCUITRY
The sensor circuitry is a simple circuit, which detects if the
mobile phone receives any message signal.
The operating frequency of the mobile phone is 900MHz or
1800MHz for communication.
LM2907-a simple F to V converter used as it operates
between this specified range .
To trigger the rectenna circuit to ON and the mobile begins to
charge using the microwave power automatically.

13. BLOCK DIAGRAM
 The whole setup looks like this :

14. PRINCIPLE OF OPERATION
The microwave signal is transmitted along with message signal
using slotted wave guide antenna
The sensor search for the mobile signal , in addition it has a
“RECTENNA”.
Rectenna receives the transmitted power and converts the
microwave power to DC power.

15. IMPLEMENTATIONS
Recently NOKIA has launched this
wireless charging technology in its new
recent mobile model “ NOKIA LUMIA
1020”.
Energy efficient chargers of all size and
shape to match the phone.

16. ADVANTAGES
One can carry their mobile phones any place even to a
remote village.
The use of wired chargers are eliminated.
The phone can be charged at any place and any time.
Electricity can be saved.
The more you talk the more you get charged.

17. DISADVANTAGES
Network traffic may cause problem in
charging.
Rate of charging is of minute range .
Charging depends on network coverage.

18. REFERENCE
[1] HAGERTY,J.A., Nonlinear Circuits and Antennas for Microwave
Energy Conversion”2009,
[2] SEDRA, A.S. and Smith K.G, “Microelectronic Circuits”, 5th
Edition, 2004
[3] www.nokialumia.com
[4] www.wikipedia.org
[5] http://en.wikipedia.org/wiki/Rectenna
[6] http://www.seminarsonly.com- Electronics Topics Retrieved