The document describes a project to wirelessly charge mobile phones using microwaves. It discusses the transmitter and receiver designs, including the use of a magnetron oscillator and rectenna made of a Schottky diode and antenna. Some advantages are wireless charging anywhere and eliminating different chargers. Disadvantages include the need for powerful devices over long distances and potential health effects of radiation. The conclusion describes a novel method of mobile phone charging without wires using microwave power.

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Guide name:
Manjunathsir
Student Name:
YADAV DANKUMAR V.
1NJ10EC013

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

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Introduction
The mobile can be charged at any time, anywhere.
The microwaves are used to charge the mobile phones.

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The Electromagnetic Spectrum
The light travels with the speed of 3*10^5 km/sec

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The Microwave Region
The license free 2.45 GHz ISM band is been selected for the purpose of this
experiment.
The 2.45GHz lies in between 2GHz to 4GHz which is the S band shown
below.

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Transmitter Design
Magnetron
Magnetron is high power microwave oscillator.
Efficiency of this high power oscillator lies between 50% and 80%.

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Self contained microwave oscillator (magnetron)

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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

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Process of Rectification
Directly converts the microwave signal into DC power.
The efficiency is up to 90% in laboratory environments.

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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

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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.

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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.

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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.

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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.

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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.

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