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7/30/2019 Wireless Charging of rfregMobile
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Wireless Charging of Mobile
Phones Using Microwaves
Ram Charan M C
1DA06EC074DR AIT
SeminarPresented by:
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Contents OVERVIEW
INTRODUCTION
MICROWAVES TRANSMITER DESIGN
RECEIVER DESIGN
WORKING PRINCIPLE
SENSOR CIRCUITRY
CONCLUSION
BIBLIOGRAPHY
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OVERVIEW
In this paper a new proposal has beenmade so as to make automatic rechargingof the mobile phones possible as you talk
in your mobile phone!This is done by use of microwaves.
The microwave signal is transmitted from
the transmitter along with the messagesignal using slotted wave guide antenna ata frequency is 2.45 GHz.
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There are minimal addition of a sensor, arectenna, and a filter to the mobile
handset.
The need for separate chargers for mobilephones is eliminated and makes charging
universal.
Thus the more you talk, the more is yourmobile phone charged
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INTRODUCTIONTHE ELECTROMAGNETIC SPECTRUM
The electromagnet ic spectrumis the range of allpossible frequencies of electromagnetic radiation.
when white light is shone through a prism it is
separated out into all the colors of the rainbow; this isthe visible spectrum.
It is easy to explain some of the properties of light bypretending that it is made of tiny particles called
photons And it is easy to explain other properties of light bypretending that it is some kind of wave.
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The Radio Window
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MICROWAVES
Microwaves are electromagnetic wave with wavelengths ranging fromas long as one meter to as short as one millimeter, or equivalently, withfrequencies between 300 MHz (0.3 GHz) and 300 GHz
Shorter microwaves are used in remote sensing. These microwaves areused for radar like the Doppler radar used in weather forecasts.Microwaves, used for radar are just a few inches long
Microwave waves are used in the communication industry and in thekitchen as away to cook foods.
Microwave radiation is still associated with energy levels that are usuallyconsidered harmless
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The ISM bands are defined
by the ITU-T in S5.138 and
S5.150 of the Radio
regulations. Here we have selected the
license free 2.45 GHz ISM
band for our purpose.
IEEE 802.11b wirelessEthernet also operates on
the 2.45 GHz band
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Radio and microwave powertransmission Power transmission via radio waves can
be made more directional, allowing longer
distance power beaming . A rectenna may be used to convert the
microwave energy back into electricity.
A human safe power density of 1 mW/cm
2
can be generated and distributed across a10 km diameter area corresponds to 750megawatts total power level.
http://en.wikipedia.org/wiki/Rectennahttp://en.wikipedia.org/wiki/Rectenna7/30/2019 Wireless Charging of rfregMobile
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BRIEF HISTORY OF MICROWAVE
POWER TRANSMISSION
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MOBILE PHONE
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TRANSMITTING BASE
STATION
A base transceiverstation (BTS) orcell siteis a piece of equipmentthat facilitates wireless
communication betweenuser equipment (UE) anda network. UEs aredevices like mobilephones (handsets), WLL
phones, computers withwirelessinternetconnectivity, WiFi andWiMAX gadgets etc
http://en.wikipedia.org/wiki/File:GSM_base_station_2.JPGhttp://en.wikipedia.org/wiki/File:GSM_base_station_2.JPGhttp://en.wikipedia.org/wiki/Wireless_internethttp://en.wikipedia.org/wiki/File:GSM_base_station_2.JPGhttp://en.wikipedia.org/wiki/File:BTS_Vodafone.jpghttp://en.wikipedia.org/wiki/Wireless_internet7/30/2019 Wireless Charging of rfregMobile
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TRANSMITTER DESIGN
THE MAGNETRON
A microwave tube in whichelectrons generated from aheated cathode are affected bymagnetic and electric fields insuch a way as to producemicrowave radiation.
It is a self-containedmicrowave oscillator thatoperates differently from thelinear-beam tubes, such as theTWT and the klystron.
Magnetrons can produce
continuous power outputs ofmore than 1 kW at a frequencyof 1 GHz.
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Magnetron is classed asa diode because it hasno grid .
Cathode is indirectlyheated& electrons are,
generated from aheated cathode, moveunder the combinedforce of a radial electricfield and an axialmagnetic field.
This causes movingelectrons to interactsynchronously withtraveling-wavecomponents of amicrowave standing-wave pattern in such a
manner that electronpotential energy isconverted to microwaveenergy with highefficiency
http://www.radartutorial.eu/08.transmitters/pic/mag06.big.gif7/30/2019 Wireless Charging of rfregMobile
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The open space between the plate and the cathode iscalled the INTERACTION SPACE. In this space theelectric and magnetic fields interact to exert force uponthe electrons.
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CROSSED-ELECTRON and MAGNETIC fields are usedin the magnetron to produce the high-power output
required in radar and communications equipment.
RECEIVER DESIGN
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RECEIVER DESIGN
A rectenna is a
rectifying antenna,converts microwaveenergy into DCelectricity.
A simple rectenna canbe constructed from aschottky diode placedbetween antenna
dipoles. The dioderectifies the currentinduced in theantenna by themicrowaves.
http://en.wikipedia.org/wiki/File:Dipolentstehung.gif7/30/2019 Wireless Charging of rfregMobile
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Rectenna
An antennacomprising a mesh of
dipoles and diodes
for absorbing
microwave energyfrom a transmitter
and converting it into
electric power.
Microwaves are receivedwith about 85% efficiency
at 2.45GHz
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Rectennae have high efficiency convertingmicrowave energy to electricity above 90%.Withthe advent of nanotechnology and MEMS the sizeof these devices can be brought down tomolecular level called optical rectenna.
Wi l t i i f
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Wireless power transmission for
Mobile phones
As our main objective is to charge the mobile phone withthe transmitted microwave after rectifying it by the rectenna,
the sensor plays an important role.
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WORKING PRINCIPLE : - THE
PROCESS OF RECTIFICATION
The key to improve transmission efficiency
is the rectifying circuit. The aim of this
study is to make a low cost and efficientpower rectifier for low and high power
levels at frequency of 2.45 GHz with good
efficiency of rectifying operation.
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This circuit is based on the optimization of the rectifier inorder to have a good matching of the input impedance atdesired frequency 2.45GHz and detection sensitivity at lowlevels of power. Optimization of circuit done by introducing the parasiticelements of the Schottky diode which were optimized toreach a good impedance matching and an importantconversion efficiency at desired frequency 2.45 GHz .
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SENSOR CIRCUITRY
The sensor circuitry detects if the mobile
phone receives any message signal.
In India the operating frequency of the mobile
phone operators is generally 900MHz or1800MHz for the GSM system for mobile
communication. Thus the usage of simple F
to V such as LM2907 converters would act as
switches to trigger the rectenna circuit to on.
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Fig shows F to V converter LM2907.Using LM2907
would greatly serve our purpose. It acts as a switch for
triggering the rectenna circuitry. Thus on the receptionof the signal the sensor circuitry directs the rectenna
circuit to ON and the mobile phone begins to charge
using the microwave power.
Advantages Disadvantages
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Advantages
Charging of mobile phonebattery is independent of theirmanufacturer and battery
make. The recharging of the mobile
phones is done automaticallyas you talk in your mobilephone
The need for separate
chargers for mobile phones iseliminated and makescharging universal.
Microwave energy apparentlyhas the potential to provideenvironmentally clean electricpower for very large number ofusers.
The mobile phone users cancarry their phones anywhereeven if the place is devoid offacilities for charging
Disadvantages
Rectenna is quite bulky , Furtherreduction in size is required.
Power level density desired for
wireless power transmission mayexceed the Human safe level.
The Mobile phone Battery is notstandardized, hence design ofreceivers may vary.
The Magnetron at the Base
transceiver station dissipates toomuch Heat and this is to bedesigned for optimum efficiencyfor wireless power transmission.
At the Base transceiver stationthere is a requirement ofmaintenance of Magnetron whichhas to be provided with the heatsink.
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CONCLUSION
Thus this paper successfully demonstrates a
novel method of using the power of the
microwave to charge the mobile phones without
the use of wired chargers. Thus this methodprovides great advantage to the mobile phone
users to carry their phones anywhere even if the
place is devoid of facilities for charging. A novel
use of the rectenna and a sensor in a mobilephone could provide a new dimension in the
revelation of mobile phone.
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BIBLIOGRAPHY 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.
5 Hawkins, Joe, et al, "Wireless Space Power Experiment,"in Proceedings of the 9th summer Conference ofNASA/USRA Advanced Design Program and AdvancedSpace Design Program, June 14-18, 1993.
MW Medley Jr and MW Medley, 'Microwave and RFcircuits: analysis, synthesis, and design', Artech House,
Norwood, MA, 1993. Falcone, Vincent J., "Atmospheric Attenuation of Microwave
Power," Journal of microwave Power, 5(4), 1970.
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