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### MICROWAVE MOBILE CHARGER

1. 1. MICROWAVE MOBILE CHARGER BISHOP JEROME INSTITUTE, KOLLAM Dept. of Electronics & Communication Engineering Page 1 CHAPTER 1 INTRODUCTION 1.1 THE ELECTROMAGNETIC SPECTRUM The electromagnetic spectrum as shown in the Fig 1.1 is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object. The electromagnetic spectrum extends from low frequencies used for modern radio to gamma radiation at the short-wavelength end, covering wavelengths from thousands of kilometers down to a fraction of the size of an atom. The long wavelength limit is the size of the universe itself, while it is thought that the short wavelength limit is in the vicinity of the Planck length, although in principle the spectrum is infinite and continuous. Some physicists pretend that light consists of tiny particles which they call photons. They travel at the speed of light. The speed of light is about 300,000,000 meters per second. When they hit something they might bounce off, go right through or get absorbed. What happens is depends on a bit and how much energy they have. If they bounce off something and then go into eye will cause to see the things they have bounced off. Some things like glass and Perspex will let them go through. These materials are transparent. Black objects absorb the photons so it results not be able to see black things. This is the problem has to be sorted out. These poor old physicists get a little bit confused when they try to explain why some photons go through a leaf, some are reflected, and some are absorbed. They say that it is because they have different amounts of energy. Other physicists pretend that light is made of waves. These physicists measure the length of the waves and this helps them to explain what happens when light hits and leaves. The light with the longest wavelength (red) is absorbed by the green stuff (chlorophyll) in the leaves. There is green light, this is allowed to pass right through or is reflected. (Indigo and violet have shorter wavelengths than blue light.)
2. 2. MICROWAVE MOBILE CHARGER BISHOP JEROME INSTITUTE, KOLLAM Dept. of Electronics & Communication Engineering Page 2 Fig 1.1: Electromagnetic spectrum It is easy to explain some of the properties of light by pretending that it is made of tiny particles called photons and it is easy to explain other properties of light by pretending that it is some kind of wave. The visible spectrum is just one small part of the electromagnetic spectrum. These electromagnetic waves are made up of two parts. The first part is an electric field. The second part is a magnetic field. So they are called as electromagnetic waves. The two fields are at right angles to each other. 1.2 MICROWAVE REGION Microwaves are good for transmitting information from one place to another because microwave energy can penetrate haze, light rain and snow, clouds, and smoke. Shorter microwaves are used in remote sensing. These microwaves are used for clouds and smoke, these waves are good for viewing the Earth from space Microwave waves are used in the communication industry and in the kitchen as a way to cook foods. Microwave radiation is still
3. 3. MICROWAVE MOBILE CHARGER BISHOP JEROME INSTITUTE, KOLLAM Dept. of Electronics & Communication Engineering Page 3 associated with energy levels that are usually considered harmless except for people with pace makers. The frequency selection is another important aspect in transmission. Here we are going to use the S band of the Microwave Spectrum, which lies between 2-4GHz.We have selected the license free 2.45 GHz ISM band for our purpose. The Industrial, Scientific and Medical (ISM) radio bands were originally reserved internationally for non-commercial use of RF electromagnetic fields for industrial, scientific and medical purposes. In recent years they have also been used for license-free error-tolerant communications applications such as wireless LANs and Bluetooth. Frequency range • L Band l to 2 GHz • S Band 2 to 4 GHz • C Band 4 to 8 GHz • X Band 8 to 12 GHz • K11 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 • V Band 46 to 56 GHz • W Band 56 to 100 GHz The S band of the Microwave Spectrum is useful for wireless charging.
4. 4. MICROWAVE MOBILE CHARGER BISHOP JEROME INSTITUTE, KOLLAM Dept. of Electronics & Communication Engineering Page 4 Fig1.2 Microwave region
5. 5. MICROWAVE MOBILE CHARGER BISHOP JEROME INSTITUTE, KOLLAM Dept. of Electronics & Communication Engineering Page 5 CHAPTER 2 LITERATURE SURVEY 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 a wide variety of devices including cell phones, laptop computers and MP3 players as well as larger objects, such as robots and electric cars. 2.1 DIFFERENT TYPES OF WIRELESS CHARGING The different types of wireless charging are: • Inductive charging, • radio charging • Resonance charging. 2.1.1 INDUCTIVE CHARGING It is used for charging mid-sized items such as cell phones, MP3 players and PDAs. In inductive charging, an adapter equipped with contact points is attached to the device's back plate. When the device requires a charge, it is placed on a conductive charging pad, which is plugged into a socket. Inductive charging carries a far lower risk of electrical shock, when compared with conductive charging, because there are no exposed conductors. The ability to fully enclose the charging connection also makes the approach attractive where water impermeability is required; for instance, inductive charging is used for implanted medical devices that require periodic or even constant external power, and for electric hygiene devices, such as toothbrushes and shavers, that are frequently used near or even in water. Inductive charging makes charging mobile devices more convenient; rather than having to connect a power cable, the device can be placed on a charge plate.
7. 7. MICROWAVE MOBILE CHARGER BISHOP JEROME INSTITUTE, KOLLAM Dept. of Electronics & Communication Engineering Page 7 CHAPTER 3 MICROWAVE MOBILE CHARGER 3.1OVERVIEW With mobile phones becoming a basic part of life, the recharging of mobile phone batteries has always been a problem. The mobile phones vary in their talk time and battery standby according to their manufacturer and batteries. All these phones irrespective of their manufacturer and batteries have to be put to recharge after the battery has drained out. The main objective of this current proposal is to make the recharging of the mobile phones independent of their manufacturer and battery make. A new proposal has been made so as to make the recharging of the mobile phones is done automatically 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 message signal using special kind of antennas called slotted wave guide antenna at a frequency of 2.45 GHz.There are minimal additions, which have to be made in the mobile handsets, which are the addition of a sensor, a ‘rectenna’, and a ‘filter’. With the above setup, the need for separate chargers for mobile phones is eliminated and makes charging universal. Thus the more you talk, the more your mobile phone will be charged. Thus this seminar 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 method provides 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 mobile phone could provide a new dimension in the revelation of mobile phone. With mobile phones becoming a basic part of life, the recharging of mobile phone batteries has always been a problem. The mobile phones vary in their talk time and battery stand by according to their manufacturer and batteries. All these phones irrespective of their manufacturer and batteries have to be put to recharge after the battery has drained out. The main objective of this current proposal is to make the recharging of the mobile phones independent of their manufacturer and battery make.
8. 8. MICROWAVE MOBILE CHARGER BISHOP JEROME INSTITUTE, KOLLAM Dept. of Electronics & Communication Engineering Page 8 3.2 BLOCK DIAGRAM Fig 3.1: Block Diagram Microwave mobile charger consists of two parts. One is transmitting part and the other is the Receiving part. At the transmitting end there is one microwave power source which is actually producing microwaves i.e magnetron and a slotted waveguide antenna. It spread the Microwaves in a space and sent it to the receiver side. Receiver side Impedance matching circuit receives the microwave signal through Recteena circuit. This circuit is nothing but the combination of filter circuit and the schottky Diode. Which actually convert our microwave in to the DC power. 3.2.1 Magnetron The Magnetron is a self-contained microwave oscillator that operates differently from the linear- beam tubes, such as the TWT and the klystron CROSSED-ELECTRON and MAGNETIC fields are used in the magnetron to produce the high-power output required in radar and communications equipment. Transmitting station with the microwave transmitter sensor Rectenna RT cable circulator waveguide Slotted waveguide Antenna mobile signal
9. 9. MICROWAVE MOBILE CHARGER BISHOP JEROME INSTITUTE, KOLLAM Dept. of Electronics & Communication Engineering Page 9 The magnetron is classed as a diode because it has no grid. A magnetic field located in the space between the plate (anode) and the cathode serves as a grid. The plate of a magnetron does not have the same physical appearance as the plate of an ordinary electron tube. Since conventional inductive-capacitive (LC) networks become impractical at microwave frequencies, the plate is fabricated into a cylindrical copper block containing resonant cavities that serve as tuned circuits. The magnetron base differs considerably from the conventional tube base. The magnetron base is short in length and has large diameter leads that are carefully. The cathode and filament are at the center of the tube and are supported by the filament leads. The filament leads are large and rigid enough to keep the cathode and filament structure fixed in position. The output lead is usually a probe or loop extending into one of the tuned cavities and coupled into a waveguide or coaxial line. The cylindrical holes around its circumference are resonant cavities. A narrow slot runs from each cavity into the central portion of the tube dividing the inner structure into as many segments as there are cavities. Alternate segments are strapped together to put the cavities in parallel with regard to the output. The cavities control the output frequency. The straps are circular, metal bands that are placed across the top of the block at the entrance slots to the cavities. It must also have good emission characteristics, particularly under return bombardment by the electrons. This is because most of the output power is provided by the large number of electrons that are emitted when high-velocity electrons return to strike the cathode. The cathode is indirectly heated and is constructed of a high-emission material. The open space between the plate and the cathode is called the INTERACTION SPACE. The cylindrical holes around its circumference are resonant cavities. A narrow slot runs from each cavity into the central portion of the tube dividing the inner structure into as many segments as there are cavities.Alternate segments are strapped together to put the cavities in parallel with regard to the output. The cavities control the output frequency.The cathode and filament are at the center of the tube and are supported by the filament leads. The filament leads are large and rigid enough to keep the cathode and filament structure fixed in position. The output lead is usually a probe or loop extending into one of the tuned cavities and coupled into a wave guide or coaxial line.
10. 10. MICROWAVE MOBILE CHARGER BISHOP JEROME INSTITUTE, KOLLAM Dept. of Electronics & Communication Engineering Page 10 Fig 3.2: Magnetron • Magnetron is a high power microwave oscillator and it is used in microwave oven and radar transmitter. • It is itself a special kind of vaccumtube that has permanent magnet in its constructions. • This magnet is setup to affect the path of travel of electrons that are in transit from cathode to the plate. • Magnetron is capable to deliver more power than reflex klystron or gunn diode. • It is a high power oscillator and has high efficiency of 50% to 80%. • Magnetron is a device which produces microwave radiation of radar application and microwaves. • Magnetron functions as self-excited microwave oscillator.
11. 11. MICROWAVE MOBILE CHARGER BISHOP JEROME INSTITUTE, KOLLAM Dept. of Electronics & Communication Engineering Page 11 • Crossed electron and magnetic fields are used to produce magnetron to produce the high power output required in radar equipment. • These multi cavity devices are used in transmitters as pulsed or cw oscillators to produce microwave radiation. • Disadvantage of magnetron is that it works only on fixed frequency • This magnet is setup to affect the path of travel of electrons that are in transit from cathode to the plate. • Magnetron functions as self-excited microwave oscillator. 3.2.2 THE SLOTTED WAVEGUIDE ANTENNA A slotted waveguide is a waveguide that is used as an antenna in microwave radar applications. Prior to its use in surface search radar, such systems used a parabolic segment reflector. The circulator is connected to a tuning waveguide section to match the waveguide impedance to the antenna input impedance. The slotted waveguide antenna consists of 8 waveguide sections with 8 slots on each section. These 64 slots radiate the power uniformly through free space to the rectenna. The slotted waveguide antenna is ideal for power transmission because of its high aperture efficiency (> 95%) and high power handling capability. 3.2.3 RECTENNA The basic addition to the mobile phone is going to be the rectenna. A rectenna is a rectifying antenna, a special type of antenna that is used to directly convert microwave energy into DC electricity. Its elements are usually arranged in a mesh pattern, giving it a distinct appearance from most antennae. A simple rectenna can be constructed from a schottky diode placed between antenna dipoles. The diode rectifies the current induced in the antenna by the microwaves.
12. 12. MICROWAVE MOBILE CHARGER BISHOP JEROME INSTITUTE, KOLLAM Dept. of Electronics & Communication Engineering Page 12 Rectenna are highly efficient at converting microwave energy to electricity. In' laboratory environments, efficiencies above 90% have been observed with regularity. Theoretically, high efficiencies can be maintained as the device shrinks, but experiments funded by the United States National Renewable Energy Laboratory have so far only obtained roughly 1% efficiency while using infrared light. Another important part of our receiver circuitry is a simple sensor. This is simply used to identify when the mobile phone user is talking. As our main objective is to charge the mobile phone with the transmitted microwave after rectifying it by the rectenna, the sensor plays an important role. The whole setup looks something like this. As our main objective is to charge the mobile phone with the transmitted microwave after rectifying it by the rectenna, the sensor plays an important role. The whole setup looks something like this. Fig3.4 Rectenna
13. 13. MICROWAVE MOBILE CHARGER BISHOP JEROME INSTITUTE, KOLLAM Dept. of Electronics & Communication Engineering Page 13 3.2.4 SENSOR CIRCUITRY The sensor circuitry is a simple circuit as shown in the Fig 6, which detects if the mobile phone receives any message signal. This is required, as the phone has to be charged as long as the user is talking Thus a simple F to V converter would serve our purpose. In India the operating frequency of the mobile phone operators is generally 900MHz or 1800MHz for the GSM system for mobile communication .Thus the usage of simple F to Y converter would act as switches to trigger the rectenna circuit to on. Fig.3.5 LM2907 A simple yet powerful F to V converter is LM2907.using LM2907 would greatly serve our purpose. It acts as a switch for triggering the rectenna circuitry. The general block diagram for the LM2097 is given below Thus a simple F to V converter would serve our purpose. In India the operating frequency of the mobile phone operators is generally 900MHz or 1800MHz for the GSM system for mobile communication. Thus the usage of simple F to Y converter would act as switches to trigger the rectenna circuit to on. Thus on the reception of the signal the sensor circuitry directs the rectenna circuit to ON and the mobile phone begins to change using the microwave power. 3.2.5 SCHOTTKY BARRIER DIODE A Schottky diode is a special type of diode with a very low forward-voltage drop. When current flows through a diode there is a small voltage drop across the diode terminals. A normal silicon
14. 14. MICROWAVE MOBILE CHARGER BISHOP JEROME INSTITUTE, KOLLAM Dept. of Electronics & Communication Engineering Page 14 diode has a voltage drop between 0.6–1.7 volts, while a Schottky diode voltage drop is between approximately 0.15–0.45 volts. This lower voltage drop can provide higher switching speed and better system efficiency. Another advantage of the Schottky barrier diode is a very low noise index that is very important for a communication receiver. A Schottky barrier diode is different from a common P/N silicon diode. The common diode is formed by connecting a P type semiconductor with an N type semiconductor, this is connecting between a semiconductor and another semiconductor; however, a Schottky barrier diode is formed by connecting a metal with a semiconductor. When the metal contacts the semiconductor, there will be a layer of potential barrier (Schottky barrier) formed on the contact surface of them, which shows a characteristic of rectification. The material of the semiconductor usually is a semiconductor of n-type (occasionally p-type), and the material of metal generally is chosen from different metals such as molybdenum, chromium, platinum and tungsten. Sputtering technique connects the metal and the semiconductor. A Schottky barrier diode is a majority carrier device, while a common diode is a minority carrier device. When a common PN diode is turned from electric connecting to circuit breakage, the redundant minority carrier on the contact surface should be removed to result in time delay. The Schottky barrier diode itself has no minority carrier, it can quickly turn from electric connecting to circuit breakage, its speed is much faster than a common P/N diode, so its reverse recovery time Trr is very short and shorter than 10 nS. And the forward voltage bias of the Schottky barrier diode is under 0.6V or so, lower than that (about 1.1V) of the common PN diode. So, The Schottky barrier diode is a comparatively ideal diode, such as for a 1 ampere limited current PN interface. 3.3PROCESS OF RECTIFICATION Studies on various microwave power rectifier configurations show that a bridge configuration is better than a single diode one. But the dimensions and the cost of that kind of solution do not meet our objective. This study consists in designing and simulating a single diode power rectifier in hybrid technology with improved sensitivity at low power levels. We achieved good matching between simulation results and measurements thanks to the optimization of the packaging of the Schottky diode.
15. 15. MICROWAVE MOBILE CHARGER BISHOP JEROME INSTITUTE, KOLLAM Dept. of Electronics & Communication Engineering Page 15 Microwave energy transmitted from space to earth apparently has the potential to provide environmentally clean electric power on a very large scale. The key to improve transmission efficiency is the rectifying circuit. The aim of this study is to make a low cost power rectifier for low and high power levels at a. The cathode and filament are at the center of the tube and are supported by the filament leads. The filament leads are large and rigid enough to keep the cathode and filament structure fixed in position. The output lead is usually a probe or loops extending into one of the tuned cavities and coupled into a waveguide or coaxial line. The plate structure, is a solid block of copper. The cylindrical holes around its circumference are resonant cavities. A narrow slot runs from each cavity into the central portion of the tube dividing the inner structure into as many segments as there are cavities. Alternate segments are strapped together to put the cavities in parallel with regard to the output. The cavities control the output frequency. The straps are circular, metal bands that are placed across the top of the block at the entrance slots to the cavities. Since the cathode must operate at high power, it must be fairly large and must also be able to withstand high operating temperatures. It must also have good emission characteristics, particularly under return bombardment by the electrons. This is because most of the output power is provided by the large number of electrons that are emitted when high-velocity electrons return to strike the cathode. The cathode is indirectly heated and is constructed of a high-emission material. The open space between the plate and the cathode is called the INTERACTION SPACE. In this space the electric and magnetic fields interact to exert force upon the electrons. Arranged in a mesh pattern so give it a distinct appearance from most antenna. A simple rectenna can be constructed from a schottky diode placed between antenna dipoles. The diode rectifies the current induced in the antenna by the microwaves. Rectenna are highly efficient at converting microwave energy to electricity. In laboratory environments, efficiencies above 90% have been observed with regularity. Some experimentation has been done with inverse rectenna, converting electricity into microwave energy, but efficiencies are much lower-only in the area of 1%.
16. 16. MICROWAVE MOBILE CHARGER BISHOP JEROME INSTITUTE, KOLLAM Dept. of Electronics & Communication Engineering Page 16 With the advent of nanotechnology and MEMS the size of these devices 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. Theoretically, high efficiencies can be maintained as the device shrinks, but experiments funded by the United States National Renewable Energy Laboratory have so far only obtained roughly 1% efficiency while using infrared light. Another important part of our receiver circuitry is a simple sensor. This is simply used to identify when the mobile phone user is talking. As our main objective is to charge the mobile phone with the transmitted microwave after rectifying it by the rectenna, the sensor plays an important role. A Schottky barrier diode is different from a common P/N silicon diode. The common diode is formed by connecting a P type semiconductor with an N type semiconductor, this is connecting between a semiconductor and another semiconductor; however, a Schottky barrier diode is formed by connecting a metal with a semiconductor. When the metal contacts the semiconductor, there will be a layer of potential barrier (Schottky barrier) formed on the contact surface of them, which shows a characteristic of rectification. The material of the semiconductor usually is a semiconductor of n-type (occasionally p-type), and the material of metal generally is chosen from different metals such as molybdenum, chromium, platinum and tungsten. Sputtering technique connects the metal and the semiconductor. A Schottky barrier diode is a majority carrier device, while a common diode is a minority carrier device. When a common PN diode is turned from electric connecting to circuit breakage, the redundant minority carrier on the contact surface should be removed to result in time delay. The Schottky barrier diode itself has no minority carrier, it can quickly turn from electric connecting to circuit breakage, its speed is much faster than a common P/N diode, so its reverse recovery time Trr is very short and shorter than 10 nS. And the forward voltage bias of the Schottky barrier diode is under 0.6V or so, lower than that of the common PN diode. So, The Schottky barrier diode is a comparatively ideal diode, such as for a 1 ampere limited current PN interface. Frequency of 2.45GHz with good efficiency of rectifying operation. The objective also is to increase the detection sensitivity at low levels of power. Different configurations can be used to convert the electromagnetic wave into DC signal, the study done in showed that the use of a
17. 17. MICROWAVE MOBILE CHARGER BISHOP JEROME INSTITUTE, KOLLAM Dept. of Electronics & Communication Engineering Page 17 bridge is better than a single diode, but the purpose of this study is to achieve a low cost microwave rectifier with single Schottky diode for low and high power levels that has a good performances. This study is divided on two kinds of technologies the first is the hybrid technology and the second is the monolithic one. The goal of this investigation is the development of a hybrid microwave rectifier with single Schottky diode. The first study of this circuit is based on the optimization of the rectifier in order to have a good matching of the Input impedance at the desired frequency 2.45GHz. Besides, the aim of the second study is the increasing of the detection sensitivity at low levels of power. This study is divided on two kinds of technologies the first is the hybrid technology and the second is the monolithic one. The goal of this investigation is the development of a hybrid microwave rectifier with single Schottky diode. The first study of this circuit is based on the optimization of the rectifier in order to have a good matching of the input impedance the desired frequency of 2.45GHz.
18. 18. MICROWAVE MOBILE CHARGER BISHOP JEROME INSTITUTE, KOLLAM Dept. of Electronics & Communication Engineering Page 18 CHAPTER 4 ADVANTAGES • The main advantage of Sensor circuitry is Reduce the usage of high electricity. • Make the recharging of the mobile phones independent of their manufacturer. • Make use of valuable EM energy. • If Sensor circuitry is Very small circuitry in size. • More economical than wired charging. • 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.
19. 19. MICROWAVE MOBILE CHARGER BISHOP JEROME INSTITUTE, KOLLAM Dept. of Electronics & Communication Engineering Page 19 CHAPTER 5 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. • The Capital Cost for practical implementation of WPT seems to be very high. • Theiris interference of microwave with present communication systems.
20. 20. MICROWAVE MOBILE CHARGER BISHOP JEROME INSTITUTE, KOLLAM Dept. of Electronics & Communication Engineering Page 20 CHAPTER 6 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 method provides 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 mobile phone could provide a new dimension in the revelation of mobile phone. In future 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. 21. MICROWAVE MOBILE CHARGER BISHOP JEROME INSTITUTE, KOLLAM Dept. of Electronics & Communication Engineering Page 21 REFERENCES [1] Tae-Whanyoo and Kai Chang, Theoretical and Experimental Development of 10 and 35 GHz rectennas IEEE Transaction on microwave Theory and Techniques. [2] 9th Conference of NASA/USRA Advanced Design Program and Advanced Hawkins, Joe, Etal, "Wireless Space Power Experiment," in Proceedings of the Space Design Program. [3] MW Medley, 'Microwave and RF circuit analysis, synthesis, and design. [4] Falcone, Vincent J., "Atmospheric Attenuation of Microwave Power", Journal of microwave Power. [5] California EMF Program 2001 - An Evaluation of the possible risks from electric and magnetic fields [6]Glenn Elert. "The Electromagnetic Spectrum, The Physics Hypertextbook". Hypertextbook.com. Retrieved 2010-10-16. [7] "Definition of frequency bands on". Vlf.it. Retrieved 2010-10-16. [8] Mohr, Peter J.; Taylor, Barry N.; Newell, David B. (2008). "CODATA Recommended Values of the Fundamental Physical Constants: 2006".Rev.Mod.Phys. 80: 633– 730.doi:10.1103/RevModPhys.80.633.Direct link to value. [9] J. J. Condon and S. M.Ransom. "Essential Radio Astronomy: Pulsar Properties". National Radio Astronomy Observatory.Retrieved 2008-01-05. [10]A. A. Abdo et al. (2007-03-20). "Discovery of TeV Gamma‐Ray Emission from the Cygnus Region of the Galaxy". The Astrophysical Journal Letters 658: