Project Begin

SEMISTER PROJECT DOCUMENTATION

Declaration of Authorship

We declare that this project titled, ‘Power generation from RF to recharge cell phones’ and the

work presented in it are our own. We confirm that:

This work will done wholly or mainly while in candidature for a bachelor degree at this

University.

Where any part of this project has not previously been submitted for a degree or any other

qualification at this University.

We have seen some other literature review from the work of others.

Authors: Signature

1. Tadelech Amdemariam -----------------------------

2. Tedesse Hayelom ------------------------------

3. Yideg Amanu ------------------------------

4. Zewdu Belay ------------------------------

Date: 13/06/2007

Supervisor: Signature

Mr. Hamdihun A. ------------------------

P.Manager:

Mr. Edemialem G. ------------------------------

Date: 13/06/2007

It is approved that this semester project has been written in compliance with the formatting rules

laid down by the school of the university.

i PREPARED BY: 5th YEAR POWER AND CONTROL STREAM STUDENTS


Acknowledgment

For our document of the semester project to arrive at its final stage, many individuals give us

their forwarding contribution since the beginning.

We express our deep sense of gratitude and sincere thanks to school of electrical and computer

engineering for giving such an opportunity and for its contribution in giving project room.

We would like to express our special thanks of gratitude to Mr. Hamdihun A., Dr. Fikerselam G.

and all of our instructors, for their valuable recommendations and gave us the golden opportunity

to do this wonderful project on the topic Power generation from RF to recharge cell phones.

Last but not least, we want to thank our friends who treasured us for our hard work and

encouraged us and finally to God who made all the things possible for giving help and patience in

going such hard time.

ii PREPARED BY: 5th YEAR POWER AND CONTROL STREAM STUDENTS


Abstract

Now a day a mobile phones became a basic part of our life. This is one of the most important

medium for the communication, the mobile phone batteries has always been problem for

recharging spatially in rural area. Mobile have to be put to recharge after the batteries has drained

out. In this paper the main purpose is shown to make the recharging of mobile phones anywhere

you want. This is done only when Power generation from RF to recharge cell phones. There is a

use of radio frequencies, the radio frequencies signal transmitted from transmitter using antennas.

This is one of the best technologies and for this purpose we are proposing a Power generation

from radio frequencies.

iii PREPARED BY: 5th YEAR POWER AND CONTROL STREAM STUDENTS


Table of Contents

Declaration of Authorship................................................................................................................i

Acknowledgment.............................................................................................................................ii

Abstract..........................................................................................................................................iii

List of figures..................................................................................................................................vi

List of Tables.................................................................................................................................vii

List of Acronyms..........................................................................................................................viii

CHAPTER ONE

1.1. Introduction........................................................................................................................1

1.2. Statement of the Problem...................................................................................................2

1.3. Objectives of the project....................................................................................................2

1.3.1. General Objectives.....................................................................................................2

1.3.2. Specific Objectives.....................................................................................................2

1.4. Methodology Used in this Project.....................................................................................2

1.5. Major Assumptions Made for the Project..........................................................................3

1.6. Scope and Limitation of the Project..................................................................................3

1.6.1. Scope of the Project....................................................................................................3

1.6.2. Limitation of the Project.............................................................................................3

1.7. Organization of the Project................................................................................................3

CHAPTER TWO

Literature Review.........................................................................................................................4

CHAPTER THREE

System Design and Analysis.........................................................................................................5

3.1. System Components and Operations.....................................................................................5

3.2. System Design and Analysis................................................................................................10

CHAPTER FOUR

Results and Discussions..............................................................................................................15

4.1. Software Simulation Results and Discussions....................................................................15

4.1.1. Simulation of antenna resonant Circuit.........................................................................15

4.1.2. Simulation of AC Amplifier Circuit.............................................................................16

4.1.3. Simulation of DC adjustable Circuit and Bridge Rectifier...........................................17

iv PREPARED BY: 5th YEAR POWER AND CONTROL STREAM STUDENTS


CHAPTER FIVE...........................................................................................................................19

Conclusion and Recommendation..............................................................................................19

5.1. Conclusion...........................................................................................................................19

5.2. Recommendations for Future Work....................................................................................20

References......................................................................................................................................21

v PREPARED BY: 5th YEAR POWER AND CONTROL STREAM STUDENTS


List of figures

Figure1.1.Block Diagram of Experimental Design…………………………………………….2

Figure 3.1. Resonant Circuit…………………………………………………………………....6

Figure 3.1. Timer IC Pin Configurations…………………………………………………..…...6

Figure 3.3. Typical Bridge Rectifier and circuit diagram……………………………....……….8

Figure 3.4. Path of current in 1st Half Cycle……………………………………………….…...9

Figure 3.5. Path of current in 2nd Half Cycle……………………………………………….…..9

Figure 3.6. Adjustable circuit and output wave………...……………………………….……....10

Figure 3.7. Approximately DC output ……………………………………………………….....10

Figure 3.8. Design of antenna resonant circuit………………………………………………….11

Figure 3.9. AC amplifier circuit design………………………………………………………....12

Figure 3.10. Bridge rectifier design……………………………………………………………..13

Figure 3.11. General circuit diagram of the project …………………………………………….14

Figure 4.1. Output voltage from antenna resonant circuit………………………………………15

Figure 4.2. Output wave form of resonant circuit……………………………………………....15

Figure 4.3.Output voltage from AC amplifier circuit…………………………………………..16

Figure 4.4. Input-output of AC amplifier ………………………………………………..……...16

Figure 4.5. Output voltage form of DC adjustable and bridge rectifier………………….……...17

Figure 4.6. Input-output wave shape of the simulation……………………………………….....17

Figure 4.7. overall project simulation and output wave form…………………………………....18

vi PREPARED BY: 5th YEAR POWER AND CONTROL STREAM STUDENTS


List of Tables

Table 3.1 NE555 IC pin configuration and their purpose……………………………………..…7

Table 4.1 recorded data from simulation ………………………………………………………...18

vii PREPARED BY: 5th YEAR POWER AND CONTROL STREAM STUDENTS


List of Acronyms

AC – Alternative Current

CTRL – Control Voltage

DC – Direct Current

DIS – Dis Charge

GND – Ground

IC – Integrated Circuit

OP-Amp – Operational Amplifier

OUT –Output

RF – Radio Frequency

THR –Threshold

TRIG –Trigger

TV – Tele-Vision

viii PREPARED BY: 5th YEAR POWER AND CONTROL STREAM STUDENTS


CHAPTER ONE

1.1. Introduction

Now a day; mobile phones became a basic part of our life. It is one of the most important

medium for the communication. The mobile phone battery has always been problem for

recharging specially in rural area.

Radio frequency energy is emitted by sources that generate high electromagnetic fields such as

TV signals, wireless radio networks and cell phone towers and using a power generating circuit

linked to a receiving antenna this free flowing energy can be captured and converted into usable

DC voltage.

As the usage of the portable electronic devices is increasing, the demands for longer battery life

are also increasing. These batteries need to be recharged or replaced periodically.

The advantages of portability and wireless communication are greatly hindered by the fact that

the devices themselves must be plugged into the walls to charge. The next generation in portable

devices is a device that receives power radio frequencies. The first step in wireless power is

providing power to mobile charging.

In this mini project we will charge any mobile battery using the output voltage from the circuit. It

produces 3.7 V DC outputs which is best suited for any mobile battery.

1 PREPARED BY: 5th YEAR POWER AND CONTROL STREAM STUDENTS

AC amplifier Resonator ckt AC to DCConvertor ckt

DC adjustable cktOutput voltage


1.2. Statement of the Problem

The mobile phone batteries have always been problem for recharging. Mobile have to be put to

recharge after the batteries has drained out, we recharge mobile phones in the electric available

place. Due to this reason mobile phones are switched off for a specific days or a week and the

customers cannot get urgent information at the right time.

Therefore, this project solves these kinds of problems especially mobile phone users in our

country.

1.3. Objectives of the project

1.3.1. General Objectives The overall goal of this project is to generate power from radio frequencies to recharge cell

phones.

1.3.2. Specific Objectives

To study energy from radio frequencies.

To analyze how electrical energy is produced from radio frequency.

To construct circuit for producing DC voltage.

1.4. Methodology Used in this Project

Our methods of work are organized and accomplished through a sequence of stages. Prior to all,

we have reviewed related literatures. Then we have made the general block diagram for our

system that enables as to easily analyze each components of the system as shown in the following

figurative expressions.

RF wave

Antenna



Figure1.1 Block Diagram of the project

1.5. Major Assumptions Made for the Project

Major Assumptions Made for the Work

We assume LC circuit instead antenna in simulator "proteus", on assumption, because it

nearly the same work.

We assume there is an input source (i.e. frequency wave), which gives us AC power.

We used full wave rectifier to convert AC-DC, finally connect it with load.

The value of materials such as; inductance (L= 0.66nH), Smoothing capacitance (C= 0.01

µF), capacitances and resistances of the amplifier circuit (C1=0.01 µF and C2 = 22 µF,

R1=1 k Ω and R2 = 22 k Ω).

1.6. Scope and Limitation of the Project

1.6.1. Scope of the Project:

Construction of prototype for the receiving frequency antenna and resonator circuit.

Construction of prototype for the AC amplifier circuit.

Construction of prototype for the AC to DC circuit.

Construction of prototype for the DC adjustable circuit.

1.6.2. Limitation of the Project

It is significant to know that this design is limited to generate 3.7v, 1.3 amps electric energy from

radio frequency to recharge cell phones and cannot be used to recharge laptops, and other electric

devices which use more than 3.7 volts.

When we simulate the project, we are not familiar by protues 8 soft ware. And therefore, we

could not understand property of this soft ware.

1.7. Organization of the Project

The organization of this project report is well detailed and vast in its coverage; it covers all the

activities encountered during the project work. The first chapter of this work includes

introduction, aims and objective, and scope. Chapter two highlight on literature review, chapter

three highlight on description of system and some of the component used were emphasized,

chapter four highlight on result and discussion, testing and simulation of power generated from

radio frequency circuit. Chapter five is all about the conclusion and recommendation.



CHAPTER TWO

Literature Review

The idea behind this project is to capture the radio frequency sent by specific transmitter using

energy harvesting circuit and store the energy in a stand then when mobile needs to be recharged,

the user put it over the stand and it starts charging [1].

Nikola Tesla is the one who first conceived the idea wireless transmission and demonstrated “the

transmission of electrical energy Without wires “that depends up on electrical conductivity as

early as 1891 [2].

In 1893, Tesla demonstrated the illumination of vacuum bulbs without using wires for power

transmission at the world Columbian exposition in Chicago. The wardenclyffe tower was

designed and constructed by Tesla mainly for wireless transmission of electrical power rather

than telegraphy [3].

Radio frequency (RF) energy harvesting, also referred to as RF energy scavenging has been

proposed and researched in the 1950s [4] using high power microwave sources, as more of a

proof-of-concept rather than a practical energy source, due to the technologies available at the

time. However, with modern advances in low power devices the situation has changed with the

technique being a viable alternative to batteries in some applications. Particularly, for wireless

devices located in sensitive or difficult access environments where battery operated equipment

might not have been previously possible. Sony Corporation in 2009 announced the development

of a highly efficient wireless power transfer system that eliminates the use of power cables from

electronic products such as television sets. Using this system, up to 60 watts of electrical energy

can be transferred over a distance of 50 cm (at an efficiency of approximately 80%,

approximately 60% including rectifier) [5].

There has been research done in the area of shrinking the charger in order to make it easier to

carry with the phone. One study in particular went on to find the lower limit of charger size [6].

But as small as the charger becomes, it still needs to be plugged in to a wall outlet.

In The recent researchers, they tried to solve the problems of wireless charging for cell phones.

But this project is not available in our country. Due to this reason we have done this project by



generating electrical power from RF to recharge mobile battery. Therefore, our project is more

significant for our country.

CHAPTER THREE

System Design and Analysis

Diodes for bridge rectifier and LC circuits (as antenna in real practice) have been selected. The

antenna starts taking Radio waves from the air. The components and devices used in our system

are explained in the sections below.

3.1. System Components and Operations

Antenna: An antenna is a device which is normally used in order to transmit or receive

electromagnetic waves [7]. Antennas demonstrate a property known as reciprocity, which means

that an antenna will maintain the same characteristics regardless if it is transmitting or receiving.

Antennas are usually used for signal transmitting and receiving purpose. There are different types

of antennas for different ranges of frequency, gains, radiation and directivity. Receiving antenna

is one of the most important portions to collect radio frequency from the air.

Resonance (LC) circuit: A resonator is a device or system that exhibits resonance or resonant

behavior at some specific frequencies called the resonance frequency. Resonators are used to

generate electrical energy and its wave form with particular frequency or to capture some specific

frequency. Usually, a resonator can be designed using capacitor and inductor.

An LC circuit, oscillating at its natural resonant frequency, can store electrical energy. A

capacitor stores energy in the electric field (E) between its plates, depending on the voltage

across it, and an inductor stores energy in its magnetic field (B), depending on the current

through it.

If a charged capacitor is connected across an inductor, current will start to flow through the

inductor, building up a magnetic field around it and reducing the charge, and therefore the

voltage, on the capacitor.


http://en.wikipedia.org/wiki/Electric_current

http://en.wikipedia.org/wiki/Magnetic_field

http://en.wikipedia.org/wiki/Voltage

http://en.wikipedia.org/wiki/Electric_field

http://en.wikipedia.org/wiki/Electrical_energy

http://en.wikipedia.org/wiki/Resonant_frequency


Figure 3.1 LC Circuit

AC Amplifier: Amplifier can be considered as a block containing the amplifying device which

has input terminal and output terminal with the output signal being much greater than that of the

input signal as it has been "Amplified”. Multi vibrator oscillators are used in many electronics

circuits and they are simple to construct. It is possible to construct them using a couple of

transistors, but it is also possible to construct a very simple multi vibrator oscillator circuit using

an operational amplifier.

The use of an operational amplifier integrated circuit is ideal from many view points. Although

circuits can be made using just two transistors, operational amplifiers are also very cheap these

days and there is often little to choose in terms of cost.

Figure 3.2 Timer IC Pin Configurations



Table 3. 1. NE555 IC pin configuration and their purpose

Pi

n

Name Purpose

1 GND Ground reference voltage, low level (0 V)

2 TRIG The OUT pin goes high and a timing interval starts when this input falls

below 1/2 of CTRL voltage (hence TRIG is typically 1/3 VCC, CTRL

being 2/3 VCC by default, if CTRL is left open).

3 OUT This output is driven to approximately 1.7 V below +VCC or GND.

4

RESET

A timing interval may be reset by driving this input to GND, but the

timing does not begin again until RESET rises above approximately 0.7

volts. Overrides TRIG which overrides THR.

5 CTRL Provides "control" access to the internal voltage divider (by default, 2/3

VCC).

6 THR The timing (OUT high) interval ends when the voltage at THR is greater

than that at CTRL (2/3 VCC if CTRL is open).

7 DIS The timing (OUT high) interval ends when the voltage at THR is greater

than that at CTRL (2/3 VCC if CTRL is open).

8 VCC Positive supply voltage, which is usually between 3 and 15 V depending

on the variation.

The Operational Amplifier or Op-amp for short is a very versatile device that can be used in a

variety of different electronic circuits and applications, from voltage amplifiers, to filters, to

signal conditioners. But one very simple and extremely useful op-amp circuit based around any

general purpose operational amplifier is the Astable Op-amp Multi vibrator.

The Op-amp Multi-vibrator is an astable oscillator circuit that generates a sinusoidal output

waveform using an RC timing network connected to the inverting input of the operational

amplifier and a voltage divider network connected to the other non-inverting input


http://en.wikipedia.org/wiki/Vcc


To look at how the op amp astable multi-vibrator circuit works take a start point where the

capacitor C1 is fully discharged and the output of the op amp is positive - it will actually be at its

positive saturated level close to the positive voltage rail.

The capacitor C1 then starts to charge up via the resistor R1. It rises asymptotically towards the

positive saturation voltage. As the end connected to the output of the op amp is at the positive

saturation voltage, +Vsat, and the rate is determined by the time constant of the combination of C1

and R1.

As the capacitor charges up the voltage rises and as the junction of the capacitor and resistor is

connected to the inverting input, when this reaches a point where the circuit switching voltage

(the voltage on the positive or non-inverting terminal) as determined by R1 and R2, the output

changes from positive to negative, i.e. -Vsat. The voltage on the non-inverting input also changes

at this point. Although many multi vibrator circuits may be provided using simple logic gates,

this operational amplifier multi vibrator circuit has the advantage that it can be used to provide an

oscillator that will generate a much higher output than that which could come from a logic circuit

running from supply. In addition to this the multi vibrator oscillator circuit is very simple,

requiring just one operational amplifier, op amp, three resistors, and a single capacitor.

The diode which connects in the output of astable multi-vibrator is used to pass only positive

values and a capacitor which connects output of astable multi-vibrator to the output resonant

circuit that carries pure sinusoidal waves. Then the output of capacitor and diode gives amplified

sinusoidal waves as the input of full-bridge rectifier.

AC to DC Voltage Converter Circuit: A Full wave rectifier is a circuit arrangement which

makes use of both half cycles of input alternating current (AC) and converts them to direct

current (DC).



(a) (b)

Figure 3.3. Typical Bridge Rectifier and circuit diagram

During the first half cycle diodes D1 and D3 are forward biased and current flows through load

resistance RL, and returns back. During this half of each input cycle, the diodes D 2 and D4 are

reverse biased and current is not allowed to flow. The flow of current is indicated by solid arrows

in the figure blow.

Figure 3.4. Path of current in 1st Half Cycle

During second half cycle diodes D2 and D4 are forward biased and current flows through load

resistance RL, and returns back. During this half of each input cycle, the diodes D 1 and D3 are

reverse biased and current is not allowed to flow. The flow of current is indicated by solid arrows

in the figure blow.



Figure 3.5. Path of current in 2nd Half Cycle

Adjustable circuit (the Smoothing Capacitor): The full-wave bridge rectifier however, gives

us a greater mean DC value (0.637 Vmax) with less superimposed ripple while the output

waveform is twice that of the frequency of the input supply frequency. We can therefore increase

its average DC output level even higher by connecting a suitable smoothing capacitor across the

output of the bridge circuit as shown below.

(a) (b)

Figure 3.6. Adjustable circuit and output wave

We know that a capacitor is an energy storing element. In the circuit, capacitor stores energy

while the input increases from zero to a peak value and, while the supply voltage decreases from

peak value to zero, capacitor starts discharging. This charging and discharging of the capacitor

will make the pulsating DC into pure DC, as shown in figure.


https://www.elprocus.com/capacitors-types-applications/


Figure 3.7 Approximately DC output

3.2. System Design and Analysis

Antenna resonance circuit design and analysis: Resonance Circuits containing L, C elements

(as shown in figure 3.8) often have special characteristics useful in many applications. Because

their frequency characteristics (impedance, voltage, or current vs. frequency) may have a sharp

maximum or minimum at certain frequencies these circuits are very important in the operation of

television receivers, radio receivers, and transmitters.

As our project aim is to extract frequency ranges from 0.5MHz to 150 MHz, we designed an

antenna resonator circuit by simple calculations. So the central frequency ω0 = 96.9MHz.

Let, Central frequency, ω0 = 96.9 MHz and L = 0.66nH.

ω0 = 1/√ (LC) …………………………………………………………….. (1)

C =1/L ω02

C = 1/0.66nF* (96.9MHz)2 = 0.161 µF

Figure3.8 design of antenna resonant circuit


https://www.elprocus.com/wp-content/uploads/2014/09/filter.jpg


AC Amplifier Circuit Design and analysis: This AC voltage is applied to the NE555 timer IC.

NE555 produces frequency proportional to the input voltage. NE555 timer IC Amplifier can be

considered as a block containing the amplifying device which has input terminal and output

terminal with the output signal being much greater than that of the input signal as it has been

"Amplified”.

The charge time (output high) is given by:

t1 = 0.693 (R1 + R2) C1 …………………………………………(2)

t1 = 0.693(1k Ω+ 22kΩ)*0.01 μF

t1 = 0.159 msec

Similarly, the discharge time (output low) by:

t2 = 0.693 (R2) C1 ……………………………………………….(3)

t2 = 0.693*22k Ω*0.01 μF

t2 = 0.152 msec

Thus the total period T is given by:

T = t1 + t2 = 0.693 (R1 + 2R2) C1 …………………………..….(4)

T = 0.693(1k Ω + 2*22k Ω)*0.01 μF

T = 0.311 msec



Figure 3.9. AC Amplifier Design

The external capacitors are charges through R1 and R2 and discharges through R2 only. Thus the

duty cycle can be set accurately by adjusting the ratio of these two resistors. In this mode of

operation, C1 charges and discharges are between 1/3 VCC and 2/3 VCC. As in the triggered mode,

the charge and discharge times and, therefore, frequency is independent of the supply voltage.

Generally, we used AC amplifier with astable multi-vibrator in our design. Because of know the

charging and discharging time of the capacitors this amplifier is preferable when we compare to

the other type of amplifiers like simple operational amplifier (Op-Amps).

AC to DC Voltage Converter Circuit design and analysis: there are two type of rectifier.

These are:

i. Half wave rectifier and

ii. Full wave rectifier

i. Half wave rectifier:

This type of rectifier converts only one half of AC into DC signal, either positive or negative

cycle. As it rectifies AC partially its efficiency is also less. Maximum efficiency is 40.6%. Half

wave rectifier needs only single diode for rectification.



ii. Full wave rectifier:

It converts entire AC into fluctuating DC that is it covert both half cycles to DC. Therefore, its

efficiency is almost double of half wave rectifier. Efficiency is 81.2 %. It consists of more than

one diode. Here positive half cycle is converted by one diode and negative half cycle is converted

by other diode.

Due to the efficiency of the rectification, full wave rectifier is preferable in our project.

Figure 3.10 Bridge Rectifier design

In the above figure 3.10 four diodes labeled D1 to D4 are arranged in “series pairs” with only two

diodes conducting current during each half cycle. During the positive half cycle of the supply,

diodes D1 and D2 conduct in series while diodes D3 and D4 are reverse biased and the current

flows through the load. As the current flowing through the load is unidirectional, so the voltage

developed across the load is also unidirectional the same as for the previous two diode full-wave

rectifier, therefore the average DC voltage across the load is 0.637Vmax.

Adjustable circuit (the Smoothing Capacitor): As we have discussed in system components

and operation, smoothing capacitor is used to remove ripples and makes approximately DC

output. However, the capacitance of the smoothing capacitor is so large, and then the output is

more DC. But it affects the generated output voltage is too small. Because of the smoothing

capacitor is considered by itself as a load. Similarly, the output is not pure DC when the value of

the smoothing capacitor is small.



Therefore, in our project we used 0.01µF capacitance value of a capacitor as a smoothing

capacitor.

Generally, design circuit diagram of the project is shown in figure 3.11.

Figure3.11. General Circuit diagram of the project

CHAPTER FOUR



Results and Discussions

4.1. Software Simulation Results and Discussions

4.1.1. Simulation of antenna resonant Circuit

Figure4.1 Output voltage from antenna resonant Circuit

The circuit diagram for the antenna resonant circuit is constructed on proteus 8 simulating

software as shown in the figure 4.1 and the corresponding AC voltage which is produced from

RF is 0.24 volt.

Figure 4.2 output wave form of resonant circuit

From the simulation result,

The generated output voltage is depend on the input frequency (i.e input frequency

increase; the generated voltage is also increase and vice versa).

The generated wave forms pure sinusoidal which means the generated voltage AC

voltage.



The generated voltage is very small, which is not charge our cell phone.

4.1.2. Simulation of AC Amplifier Circuit

Figure 4.3 Output AC voltage from AC Amplifier Circuit

The circuit diagram for the AC amplifier circuit is constructed on proteus 8 simulating software

as shown in the figure 4.3 and the corresponding amplified AC voltage which is produced from a

RF of 10 MHz is 1.39 volt.

Figure 4.4 Input – Output wave form of AC Amplifier Circuit



From the simulation result,

The generated voltage from resonant circuit as input of AC amplifier and AC amplifier is

amplifies the input voltage which is sufficient to recharge mobile phones.

4.1.3. Simulation of DC adjustable Circuit and Bridge Rectifier

Figure 4.5 Output DC voltages from DC Adjustable Circuit and Bridge Rectifier

The circuit diagram is constructed on proteus 8 simulating software as shown in the figure 4.5

and the corresponding DC output voltage which is produced from a RF of 100 MHz is 4.00 volt.

Figure4.6 Input-Output wave Shape of the simulation

From the output wave form and measured voltage shown in the above figure 4.6 shows that the

input sinusoidal wave (AC voltage) was converted to approximately DC wave (voltage). This



shows that the purpose of Bridge rectifier and smoothing capacitor are play a great role to convert

AC voltage into pure DC voltage.

Generally, in the soft ware simulation shows in figure 4.7 bellow. From this simulation the

following data is recorded from different frequency ranges.

Table 4.1 recorded data from simulation

Frequency range (MHz) DC output voltage (V)

0 0

0.1 – 0.5 0.05

0.5 – 20 2.29

20 – 40 2.48

40 – 60 3.02

60 – 80 3.51

80 – 100 3.87

100 – 150 4.01

(a) (b)

Figure 4.7. overall project simulation and output wave form



CHAPTER FIVE

Conclusion and Recommendation

5.1. Conclusion

Going through the planning, flow process, design and software implementation, the system has

been a tough one; the chapters’ one up to four has actually tried as much as possible to explain

strongly almost all what is involved in the simulation of this project. After the complete design of

the system, the deviation between the expected result and the actual result was very close. The

performance and efficiency was beyond expectation.

The use of technologies has increased lately, and the uses are searching for everything can make

their lives as easy as possible, so to implement such an idea will be useful and serve many people

who really need their mobiles to be charged in some critical situations and far places where

electric power supply is not available.

This project is also plays a great role for the community especially who lives in rural area.

This project is done by using receiver antenna, resonant circuit, AC amplifier, bridge rectifier and

smoothing capacitor to recharge cell phones.

As we have seen from simulation of the project, the generated voltage is depending on the input

frequency. This means that when the input frequency is higher, the generated electrical energy is

high and vice versa.

Generally, we use frequency ranges greater than 85 MHz is enough to recharge cell phones.



5.2. Recommendations for Future Work

In this mini project we already finished the design and simulation parts. Farther more, the hard

ware implementation of this project will be done for the future and the generating electrical

power which is enough to recharge a cell phone.

This project suggests to the others that someone who will improves or modifies the project to

generate enough electrical energy from radio frequency to recharge once more than two mobile

batteries and laptops.



References

[1]. Brown, W. Mims, J. Heenan, N. “An experimental microwave- powered helicopter”

Raytheon Company, Burlington, A, USA; 1965 IEEE International Record, vol. 13, part 5,

pp.225-235.

[2]. Nikola Tesla,”The Transmission of Electrical Energy without Wires as a Means for

Furthering peace,” Electrical World and Engineer.Jan.7, p.21, 1905.

[3]. D. Bouchouicha, F. DuPont, M. Latrach, L.Ventura “Ambient RF Energy Harvesting”

STMicroelectronics, 16 Rue Pierre et Marie Curie 37071 Tours France,

[4]. R. M. Dickinson, "Evaluation of a microwave high-power exception-conversion array for

wireless power transmission," Jet Propulsion Laboratory, California Institute of Technology,

Pasadena, CA, Tech. Memo 33-741, Sept. 1975.

[5]. http://en.Wikipedia.org/Wiki/Sony.

[6]. Sabate, J. A., Kustera, D. and Sridhar, S., Cell-Phone Battery Charger Miniaturization. IEEE

Journal 2000.

[7]. IEEE, "IEEE Standard Definitions of Terms for Antennas," IEEE, pp. 0-1, February 1983.

[Online]. Available:http://ieeexplore.ieee.org/stamp/stamp.jsp?

tp=&arnumber=30651&isnumber=1290


http://en.Wikipedia.org/Wiki/Sony

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