CHARGING OF MOBILE PHONES USING MICROWAVES

by:

RAKSHITHA EC dept.

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OVERVIEW INTRODUCTION ELECTROMAGNETIC SPECTRUM MICROWAVE REGION TRANSMITTER DESIGN RECEIVER DESIGN MERITS AND DEMERITS COMMON SAFETY CONCERNS CONCLUSION REFERENCES

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INTRODUCTION Portable electronic devices are very

popular nowadays.

Wireless charging is any of several methods of charging batteries without the use of cables or device-specific AC adaptors.

Wireless charging can be used for variety of devices including cell phones, laptop ,MP3 players as well as larger objects, such as robots and electric cars.

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ELECTROMAGNETIC SPECTRUMSPECTRUM: when white light is shown through a prism it is separated out into all the colours of the rainbow; this is the visible spectrum.

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ELECTROMAGNETIC WAVES ELECTRIC FIELD MAGNETIC FIELD

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MICROWAVE REGION Range is 1mm to 30cm. Microwaves are good for transmitting information from one place to another because microwave energy can penetrate haze, light rain and snow, clouds, and smoke.

Microwaves are used in the communication industry and in the kitchen as a way to cook foods.

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TRANSMITTER DESIGN

MAGNETRON: A magnetron is a high power microwave oscillator in which the potential energy of an electron cloud near the cathode is converted into RF energy in a series of cavity resonators.

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Magnetron is 4 cm in diameter.

ANODE and CATHODE

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The anode is the foundation of the magnetron circuit.

It generally consists of an even number of microwave cavities arranged in radial fashion as shown.

There are three possible anode configurations: Hole-and-slot, Vane tip, Rising sun.

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CATHODE

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The cathode of a magnetron is the part which makes the magnetron an active device.

This provides the electrons through which the mechanism of energy transfer is accomplished.

The cathode is usually located in the center of the anode and is made up of a hollow cylinder of emissive material surrounding a heater.

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RECEIVER DESIGN

LPF LPF LPFLPFMICROWAVE to DC POWER

LOAD

RECTENNA

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A rectenna is a rectifying antenna, that is used to directly convert microwave energy into DC electricity.

With the advent of nanotechnology and MEMS the size of these devices can be brought down to molecular level.

Similar devices, could be used to convert light into electricity at much greater efficiencies. This type of device is called an optical rectenna.

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SENSOR CIRCUITRY Another part of our receiver

circuitry is a simple sensor.

This is simply used to identify when the mobile phone user is talking.

The sensor circuitry is a simple circuit, which detects if the mobile phone receives any message signal.

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….Contd This is required, as the phone has to be charged as long as the user is talking.

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.

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Using Magnetron, we can convert Electrical

energy to Microwave energy, this energy is

transmitted through the tower and is received

by Rectenna which is a small circuit placed in

our mobile, that converts Microwave energy

back to Electrical energy.

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MERITSCan get rid of the tangle of cords and wires.

People wouldn't have to worry about losing charging adapters and other accessories.

Majority of wireless chargers can sense how much power each device needs, so batteries are not typically overcharged.

Instead of having to plug things into the wall, people could simply carry them along.

Charging can be done anywhere and anytime.

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DEMERITSHigher cost when compared to wired

chargers.

Generate more heat than wired chargers, which can be considered a danger despite the somewhat smaller chances of electric shock when it comes to wireless charging devices.

High power microwave signals can be painful and dangerous.

 

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COMMON SAFETY CONCERNS The common reaction to

microwave transmission is one of concern, as microwaves are generally perceived by the public as dangerous forms of radiation.

Microwave power transmission systems are generally proposed to have only low intensity at the rectenna.

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Research has involved exposing multiple generations of animals to microwave radiation of this or higher intensity, and no health issues have been found.

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…contdScientists divide the electromagnetic spectrum into “ionizing” and “non-ionizing”.

Ionizing radiation--- x-rays and atomic radiation, causes cancer.

Non-ionizing radiation---microwave radiation, is supposed to be safe.

Controlled use for communication purpose is always safe.

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FUTURE SCOPE Sony and Intel are having a go at making it

work.

While it may seem unlikely and impossible, Nokia has actually developed a mobile phone prototype which charges without wires.

Currently, the unnamed Nokia device is only able to collect about 5 mw of residual energy.

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CONCLUSIONAs the wireless technology is getting

popular nowadays, the demand of battery is also increasing. The battery needs to be recharged or changed eventually.

A novel method of using the power of the microwave to charge the mobile phones without the use of wired chargers.

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REFERENCES5 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.

MW Medley Jr and MW Medley, 'Microwave and RF circuits: analysis, synthesis and design', Artech House, Norwood, MA, 1993.

Falcone, Vincent J., "Atmospheric Attenuation of Microwave Power," Journal of microwave Power, 5(4), 1970.

www.google.comWikipedia, the free encyclopedia.

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THANK YOU