This document outlines the design of a system to wirelessly charge mobile phones using microwaves. It describes a transmitter that uses a magnetron to transmit microwaves along with voice signals. Mobile phones would be outfitted with a rectenna and sensor circuitry. The rectenna uses a Schottky diode to convert received microwaves into DC power for charging. This design could allow mobile phones to charge during calls without needing a separate charger. Potential advantages include universal charging compatibility and no standalone chargers needed. Disadvantages include the transmitter and receiver requiring high power and potential health effects from microwave radiation.

2. Guide name:
Asso. Prof. Ahmeduddin Zaker
Student Name:
Mohammed Yaheeya ahmed
10081A0439

4. Contents
Introduction
Transmitter design
Receiver design
Rectification antenna
Schottky diode
Sensor circuitry
Advantages and Disadvantages
Future scope
Conclusion

5. Introduction
 The mobile can be charged at any time, anywhere.
 Mobile can be charged just by making a call.
 The microwaves are used to charge the mobile phones.
 Mobile phones becoming basic part of life
 Recharging of mobile phones is a big problem

6.  Objective—to recharge any mobile phone independent of
manufacturer and battery make
 Achieved by recharging battery while talking using microwaves
More you talk more the mobile get charged!
 No separate mobile charger
Removal of talk time and battery stand by from mobile specifications
Additives to mobile handsets:
Sensor
Rectenna

7. 7
WHAT’S HAPPENING?
 Microwave signal is transmitted from transmitter along
with message signal using slotted waveguide antenna at
frequency 2.45 GHz
Charging made universal

8. Microwave region of
electromagnetic spectrum
 The light travels with the speed of 3*10^5 km/sec
 We choose s –band of microwave region(2-4GHz)
 Electromagnetic waves are made up of two parts
1. Electric field
2. Magnetic field
 These two fields are at right angles to each other
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
8

9. MICROWAVE REGION
Wavelength : 1 mm-30 cm
Microwave can be used for:
1. Measuring body temperature
2. Transmitting information
3. Remote sensing
4. RADAR
5. Communication

10. Transmitter Design
Magnetron
Magnetron is high power microwave oscillator.
Efficiency of this high power oscillator lies between 50% and 80%.
Crossed electron and magnetic fields are used.

11. Self contained microwave oscillator (magnetron)

12. The Magnetron

13. Receiver design
An additional feature to the mobile is RECTENNA.
RECTENNA  Rectification + Antenna
Transmitting station
with the microwave
transmitter
sensor
Rectenna
RT cable
circulator
waveguide
Slotted waveguide
Antenna
mobile signal

14. Process of Rectification
Comprises of a dipoles and diodes.
Usually its elements are arranged in the mesh pattern.
Directly converts the microwave signal into DC power.
The efficiency is up to 90% in laboratory environments.

15. Schottky diode
A Schottky barrier diode -- majority carrier device
Common diode -- minority carrier device.
Its reverse recovery time Trr is very short and shorter than 10 nS.
The forward voltage bias of the Schottky barrier diode is under 0.6V.
This is a comparatively ideal diode, such as for a 1 ampere limit
current PN interface.
P=0.6*1=0.6W  Schottky diode
P=1.1*1=1.1W  common diode
Power comparison between common diode and Schottky diode

16. Sensor circuitry
The sensor circuitry is a simple circuit, which detects if the mobile phone
receives any message signal.
 In India the operating frequency of the mobile phone operators is
generally 900MHz or 1800MHz for the GSM system for mobile
communication.
 A simple yet powerful F to V converter is LM2907.

17. Advantages
Wireless energy transfer can potentially recharge the mobile phones
without chords.
 Only one microwave transmitter can serve to all the service providers in
that area.
The need of different types of chargers by different manufacturers is
totally eliminated.

18. Disadvantages
The transmitter and receiver also should be very powerful devices as
the distance increases.
 Wireless transmission of the energy causes some drastic effects to
human body, because of its radiation.
 Practical possibilities are not yet applicable as there is no much
advancement in this field.

19. Conclusion
 A novel method of using the power of the microwave to charge the
mobile phones without the use of wired chargers.
 This method provides great advantage to the mobile phone users to
carry their phones anywhere even if the place is devoid of facilities
for charging.

20. Future scope
 The wireless charging can even be done using the data exchange as
now only its only been implemented for voice calls.
 With the advent of nanotechnology and MEMS the size of these
rectennas can be brought down to molecular level. It has been
theorized that similar devices, scaled down to the proportions used in
nanotechnology, could be used to convert light into electricity at much
greater efficiencies than what is currently possible with solar cells. This
type of device is called an optical rectenna.

21. Reference
1. Tae-Whan yoo and Kai Chang, “Theoretical and Experimental
Development of 10 and 35 GHz rectennas” IEEE Transaction on
Microwave Theory and Techniques, vol. 40. No.6. June. 1992.
2. 5 Hawkins, Joe, et al, “ Wireless Space Power Experiment,” in
proceedings of the 9th summer Conference of NASA/USRA Advanced
Design Program and Advanced Space Design Program, June 14-18,
1993.
3. MW Medley Jr and MW Medley, ‘Microwave and RF circuits: analysis,
synthesis and design’, Artech House, Norwood, MA, 1993.
4. Falone, Vincent J., “Atmospheric Attenuation of Microwave Power,”
Journal of microwave Power, 5(4), 1970.