ACADEMIC SESSION 2017/2018SEMESTER 2EEE 276ELECTROMAGNETIC THEORYPROJECT TITLE: ANTENNA IN MOBILE PHONESNAME: MICHELLE CHONG AIE YEEGROUP NO: 10EMAIL: [email protected] ID: 134249DATE: 21 MAY 2018Table of contentsNo Topic Page1 Table of contents 22 Abstract 3-43 Literature review 54 Introduction 65 Electromagnetism lawTheorySystem and structure 7-86 Impact of electromagnetic waves used in the systemPositive impactsNegative impacts 9-127 Application of antenna in mobile phonesMedical Health CareSocialTechnology evolution 13-148 Future projections of applications of antenna in mobile phonesInternal integrated antennas for mobile phones3D printed antennasAntenna miniaturisationDigital antenna 15-169 Conclusion 1710 Reference 18-1911 Appendix 20-22AbstractCell phones are powered by electricity and they use electric and magnetic fields (EMF), also known as electromagnetic waves, to establish a wireless communication link between a cell phone and the nearest base station. This is done by transmitting radio waves which are then picked up by the antenna at the base station.
My major motivation of study in this application is looking at the mobile industry experiencing a dramatic growth. It evolved from analogue to digital 2G (GSM), then to high date rate cellular wireless communication such as 3G (WCDMA), and further to packet optimized 3.5G (HSPA) and 4G (LTE and LTE advanced) systems.
Today, the main design challenges of mobile phone antenna are the requirements of small size, built in structure, and multi systems in multi bands, including all cellular 2G, 3G, 4G, and other non-cellular radio-frequency (RF) bands, and moreover the need for a nice appearance and meeting all standards and requirements. These motivated me to deepen my knowledge on the application of electromagnetic waves in the antenna of mobile phones as well as similar impacts of this application on other aspects like medical health and technology. The objectives of using an antenna in a mobile phone is to obtain high data transmission rate and low bit error probability in transmitting the radio signals. Besides that, antennas provides two-way communication by transmitting and receiving signals in the form of radio waves through it antenna. Back in the 19th century, another piece of electrical equipment called the telegraph was the height of communication technology. A telegraph was a simple electrical circuit stretching many miles between two towns, typically alongside a railroad line. Messages could be sent back and forth down the telegraph line as bursts of electricity.
Telegraphs revolutionized communications, but they were slow and rather laborious to use. One of the main difficulties was that people had to learn Morse code before they could send and receive messages. Another problem was that messages had to be sent and received at special telegraph offices because it was not possible to get them sent directly to your own home. Mobile phones changed all that. Another objective of the application of antennas in mobile phones help speed up two-way communication making it faster and more efficient to communicate with friends and families despite the distance.
Emergency calls can also be made to another person regardless of the distance between the caller and the receiver. Although antennas in mobile phones brings about many benefits, it also has many disadvantages. Mobile phones are the most important source of radio frequency (RF) fields today in our environment. The highest exposure caused by them can be of the same magnitude as the exposure limits. Some of the negative impacts are hormonal imbalance, biological effects, thermal effects due to heat energy being released, and many more. In general, antennas in mobile phones works with Faraday’s law of electromagnetic induction.
The antenna performance is influenced by the number of turns and the area of each loop. The radio waves transmitted from the base station antenna travel through the air at the speed of light. When the waves arrive at the receiver antenna of the mobile phone, they make electrons vibrate inside it. This produces an electric current that recreates the original signal. Transmitter and receiver antennas are often very similar in design.Literature reviewAs a background work for this assignment, I have read three papers published in journals. The three journals are entitled “Capacity analysis of inhomogeneous hybrid wireless networks using directional antennas”, “Effect of mobile phone radiations on oral health” and “Small Antennas for Medical Applications”.
“Capacity analysis of inhomogeneous hybrid wireless networks using directional antennas” gives a detailed explanation on the laws governing the application of electromagnetic waves in mobile phones and how it is applied in transmitting the radio wave signals to the antennas of mobile phones. Some of the laws are Faraday’s law and electromagnetic induction. The second journal explains on the positive and negative impacts of mobile phone radiations on human health and some precautions that can be taken to prevent negative impacts like thermal effects, stress, and biological impacts from affecting human health. Next, the third journal explains on the applications of electromagnetic waves in antennas in medical health care. This applications are similar to the applications of antennas in mobile phones in transmitting signals. For instance, antennas are used to take insulin pumps, deep brain simulations, glucose monitoring, endoscopy as well as MRI (magnetic resonance imaging). In my opinion, the application electromagnetic waves in antenna of mobile phones have brought a huge advancement in technology.
This application helped speed up two-way communication making it faster and more efficient to communicate with friends and families despite the distance. Emergency calls can also be made to another person regardless of the distance between the caller and the receiver. Although antennas in mobile phones brings about many benefits, it also many disadvantages. Mobile phones are the most important source of radio frequency (RF) fields today in our environment. The highest exposure caused by them can be of the same magnitude as the exposure limits.
This brings about many health hazard to all the citizens using mobile phones. In the future, similar applications utilizing radio waves can be projected and already are in the process of development. In my opinion, although new technologies will be developed utilizing radio waves that can bring about many benefits and advantages to the society, safety measures and precautions should be taken so that it does not affect our health whether it is in a short term range or a long term range.
IntroductionCell phones are powered by electricity and they use electric and magnetic fields (EMF), also known as electromagnetic waves, to establish a wireless communication link between a cell phone and the nearest base station. Generally speaking, when one is talking the cell phone is giving off electromagnetic waves with information riding on them. When one is listening, the cell phone is capturing the wanted electromagnetic waves from the space. Electromagnetic waves go out and come into a cell phone through its antenna. A mobile phone has both transmitter and receiver sections. When the mobile phone is turned on, it emits radio waves that consist of radio frequency (RF) energy, which is a form of electromagnetic radiation moving at the speed of light.
It works by transmitting radio wave signals to nearby base stations and receiving radio wave signals back from the nearby base stations. When talking on a mobile phone, voice is captured through its microphone and a radio signal is generated from the mobile’s circuitry. The radio signal is transmitted through its antenna, which radiates through space. This transmitted radio wave is picked up by the antenna at the base station. Then the mobile phone and base station start communicating back and forth through radio waves transmitted from their respective antennae. Every antenna, either on a mobile phone or tower, radiates electromagnetic waves.
Radio waves are the strongest near the mobile phone antenna but get weaker and weaker as we move away from the phone. The adaptation of smart antenna techniques in future wireless systems is expected to have a significant impact on the efficient use of the spectrum, the minimization of the cost of establishing new wireless networks, the optimization of service quality, and realization of the transparent operation across multi technology wireless networks. However, mobile phones are the most important source of radio frequency (RF) fields today in our environment. The highest exposure caused by them can be of the same magnitude as the exposure limits.
Several factors affect the RF exposure of a mobile phone user. Most important are the transmit power of the mobile phone and how much of the emitted energy of the radio waves are absorbed in the phone user’s head. There are some negative impacts when RF fields are exposed to human being. For instance, biological effects, hormonal imbalance, as well as thermal effects are some of the negative impacts of RF radiation by the antenna of mobile phones.ReportElectromagnetism lawTheoryAmpere’s lawAmpere’s Law states that for any closed loop path, the sum of the length elements times the magnetic field in the direction of the length element is equal to the permeability times the electric current enclosed in the loop.
Faraday’s lawFaraday’s law states that when magnetic flus linked to a circuit changes, an electromotive force is induced in the circuit proportional to the rate of change of flux linkage.Lenz’s lawLenz’s law states that an induced current in a closed conducting loop will appear in such a direction that it opposes the change that produced it.Both law yield an equation of ? = -Nd?dt where ? is the electromotive force induced; N is the number of turns of the coil used; d?dt is the rate of change of flux linkage.
?=BA where B is the magnetic field enclosed and A is the area of the coil. This formula is then generalized by the Maxwell’s Equations (?×B=dBdt ). Gauss’s lawThe electric flux through an area is defined as the electric field multiplied by the area of the surface projected in a plane perpendicular to the field. Gauss’s Law is a general law applying to any closed surface.Electromagnetic inductionFaraday’s law of induction is a basic law of electromagnetism predicting how a magnetic field will interact with an electric circuit to produce an electromotive force (EMF)—a phenomenon called electromagnetic induction.System and structure Magnetic loop antennaAntenna is to convert an electromagnetic wave into a voltage and voltage into an electromagnetic wave.
A magnetic loop antenna is a winding of copper wire around a frame (for air-core loops) or around ferromagnetic material (for ferrite loops). A magnetic loop antenna is actually sensitive to the magnetic field and not the electric field (it is also called a magnetic loop). The Faraday’s law of induction (or the law of electromagnetic induction) states that the induced electromotive force in a loop is directly proportional to the time rate of change of magnetic flux ?(t) through the loop. The antenna performance is influenced by the number of turns and the area of each loop. A magnetic loop antenna in a mobile phone produces an electric current that recreates the original signal efficiently.Impedance matching networkThe resistive, inductive and capacitive elements influence the performance of the antenna.
These elements allow maximum power transfer from the antenna of the mobile phone to the transceiver. An inductance in the antenna mainly results from the windings inductance, but also from the inductance of the wire itself. A radiation resistance present in the antennas of the mobile phone corresponding to the “losses” resulting from the conversion of the electromagnetic energy to electric energy. The inductance and resistance present in the antenna reduces linearity and provides a resonant behaviour in the antenna which allows for maximum power transfer in mobile phones. Some transceivers and antennas are specifically designed with impedances of 50 ohms (resistive) at their inputs (or outputs). In that case, they can be directly integrated and connected with 50- ohm transmission lines and achieve close to maximum power transfer.Impact of electromagnetic waves used in the systemPositive impactsNon-ionising radiationRadiofrequency (RF) radiation, which includes radio waves is at the low-energy end of the electromagnetic spectrum.
It is a type of non-ionizing radiation. Non-ionizing radiation has enough energy to move atoms in a molecule around or cause them to vibrate, but not enough to ionize (remove charged particles such as electrons). RF radiation has lower energy than some other types of non-ionizing radiation, like visible light and infrared, but it has higher energy than extremely low-frequency (ELF) radiation. Radio signals are also emitted by natural sources like the sun, the Earth and the ionosphere.
Therefore, radio waves are renewable can be produced easily and does not need resources from the earth. Negative impacts Thermal effectsAntennas in mobile phones releases heat energy when it transmits and receives radio wave signals. The heat generated due to the absorption of electromagnetic radiations like radio frequency radiations is called thermal effect. When mobile phones are used for a long time, the heating effect can occur near the head causing a rise in temperature in the head, on the head surface, neck, ear pinna, internal ear, brain and eyes.
The heating caused by the mobile phone mainly occurs in the head and neck region which is neutralized by the brain’s blood circulation, but cornea of the eye lacks blood supply. Therefore, it does not have any temperature regulation, so the heat generated cannot be removed causing high probability of a person having premature cataract. Exposure to RF radiations also causes pain in the ear without any specific reasons like infection. This may be due to increased stress on the delicate structures of the internal ear or ear drum by the radiation. Other body parts are also subject to heat rise due to radio frequency radiation.
This causes damage of tissue cells in the body because of the body’s inability to cope with or dissipate the excessive heat that could be generated during the exposure to high radio frequency radiations. Two areas of the body, the eyes and the testes, are particularly vulnerable to RF heating because of the relative lack of available blood flow to dissipate the excessive heat load. The proportion of the total transmit energy absorbed by the head is defined by the model of the mobile phone and the way of using the phone. When holding the phone against the ear, a significant part of the energy is absorbed in the user’s head. The user can decrease the exposure best using a hands-free device and placing the phone elsewhere, for instance on a table.
This way most of the energy emitted by the mobile phone is directed towards the base stations and only a very small part is absorbed by the user. At relatively low levels of exposure to RF radiation, that is, levels lower than those that would produce significant heating, the evidence for harmful biological effects is ambiguous and unproven. The various short term health symptoms associated with thermal effects due to mobile phone usage are burning and tingling sensations in the skin of head and extremities, headaches, fatigue, dizziness, sleep disturbances, loss of mental attention, reaction times and memory retentiveness, malaise, tachycardia and disturbances of the digestive system. Many studies have shown effects on behaviour, sleep, electroencephalograph, sperm count and quality. Therefore, to decrease thermal effects caused by radio frequency radiation, mobile phones should be used hands-free to decrease the radiation to the head, and should be kept away from the body and not to use the telephone in a car without an external antenna. Several nations have also advised moderate use of mobile phones for children.Hormonal imbalanceExposure to high levels of electromagnetic radiations like radio frequency radiation causes hormonal imbalance in our body.
These exposure increases serum oestrogen levels in women and increases testosterone levels in men. The increased levels of oestrogen develop the risk of cancer and decreased level of testosterone has been related to development of prostate and testicular cancers. Breast cancer was one of the most observed in women while that of prostate, pancreas, bowel, skin, lung, and blood also increases in both men and women due to the exposure of radio frequency radiations from the antenna of mobile phones. Children and teenagers, before the age of 20 are more likely to get brain cancer, as their brain is not fully developed and radiation penetration is much deeper. Another hormone called, melatonin, secreted by pineal gland in brain and is responsible for sleep cycle is also effected by radio frequency radiations. The level of melatonin is higher at night and is low during the day.
It is produced almost 90 minutes after we fall asleep. When this hormone is inhibited by radiations many problems are caused like sleep disorders, insomnia, and headaches. The cells are repaired and rejuvenated while sleeping but lack of sleep can lead to development of cancer.Non-thermal effects (Biological effects)Biological effect or more commonly known as non-thermal effect refers to the effect when radio frequency radiations are exposed to human beings causing physiological changes evidently but the temperature of the body remains unchanged. Some of the symptoms caused by biological effects are familiar tinnitus, headache, faint, irascibility, fatigue, sense of heat, discomfort of scalp, loss of hair, faintness of eyesight, loss of appetite, memory fading, audition fading, worse quality of sleeping. When using both normal and wireless hands-free devices, one should remember that the phone in the pocket (against the body) emits about as much RF radiation to the nearby tissues as it would emit to the head when the phone is held against the ear.
Even a small distance between the body and the phone however decreases the exposure substantially. Therefore it is sensible to carry the mobile phone or placing it in a belt case than in the pocket.Interference with medical devices (pacemaker)Radio frequency energy (RF) from cell phones can interact with some electronic devices. This type of interference is called electromagnetic interference (EMI). When electromagnetic interference (EMI) occurs, it could affect a pacemaker in many ways. Firstly, it stops the pacemaker from delivering the stimulating pulses that regulate the heart’s rhythm.
Besides that, EMI causes irregular pulses to be delivered from the pacemaker and causes the pacemaker to ignore the heart’s own rhythm and deliver pulses at a fixed rate. Therefore, people with pacemakers may want to take some simple precautions to be sure that their cell phones don’t cause a problem. For example, they should hold their mobile phones to the ear on the opposite side of the body where the pacemaker is implanted.
Some extra distance between the pacemaker and the phone should be maintained. Placing the mobile phone near to the pacemaker, for instance in their shirt pocket, should be avoided. Practicing some of the above safe mobile phone usage habits and avoiding excessive use can lead to minimize the health hazards from the radiations of mobile phones. Causes explosion if used at a petrol stationWhen electromagnetic radiations are produced while one is picking up a call at a petrol station, it sparks fire and causes an explosion. This is because radio frequency (RF) radiations are produced when the mobile phone’s signal is connected to the telecommunication company’s substation system. Besides that, heat from the weather can also render the radio frequency (RF) radiation more sensitive causing a counter reaction and spark a fire in the mobile phone.
If the weather is hot, vapour would be produced from the gas at the petrol station and radio frequency (RF) radiation will react with it to cause a fire. Application of antenna in mobile phonesMedical health careIn medical health care, antennas are used to take insulin pumps, deep brain simulations, glucose monitoring and endoscopy. These are few examples of applications that takes advantage of remote monitoring system and body implantable unit using the same system as antennas in mobile phones. Body implantable devices are widely researched for humans, in the applications such as monitoring blood pressure and temperature, tracking dependent people or lost pets, wirelessly transferring diagnostic information from an electronic device implanted in the human body for human care and safety, such as a pacemaker, to an external RF receiver. The key and critical component of RF linked medical devices is the integrated implantable antenna, which enables bidirectional communication with the exterior monitoring control equipment. Patch designs are currently receiving considerable attention for implantable antennas because they are highly flexible in design, shape and conformability, thus allowing for easy miniaturization and integration into the shape of implantable medical device.
Antennas can be implanted into human bodies or can just be mounted over the torso (skin-fat-muscle) to form a bio-communication system between medical devices and exterior instruments for short range biotelemetry applications. Remote monitoring systems facilitate the diagnosis of diseases and favour the hospital at home by reducing the hospitalization period. Antennas are also used in wireless capsule endoscopy and MRI (magnetic resonance imaging), which is also similar to the application of antennas in mobile phones which uses radio waves to send signals. Some examples of antennas for MRI system which are also known as RF (radio frequency) coils are head coil, breast coil, surface coil, and knee coil. During the MR (magnetic resonance) imaging, these kind of antennas radiate electromagnetic (EM) pulses which are radio waves to the human body and in response receive the NMR (nuclear magnetic resonance) signals emitted from the nuclei, which constitutes the human body.
Fundamental frequency of the EM pulses and frequency of the NMR signals are placed in very high frequency (VHF) band. Therefore, the antennas are classified as electrically small antennas. SocialMobile phones acts as a device that provides two-way communication by transmitting and receiving signals in the form of radio waves through it antenna. The application of antennas in mobile phones allows one to receive calls as well as to make calls in order to communicate. This application has many social impacts.
For instance, it helps patients or doctor to make emergency calls in the hospital under any circumstances which could save lives. If a specialist is not available in the hospital, phone calls could be made and symptoms could be explained through the phone or a second opinion could be given through the phone from the specialist if needed. Mobile phones also helps the society to stay connected and keep in touch with friends and family.Technology evolutionBaby monitorA baby monitor, also known as a baby alarm is a certain type of digital cordless telephone, transmits the voice of a waking-up baby via a radio signal from the antenna of the transmitting baby unit to the antenna of the receiving parent unit. Baby monitors generally use wireless systems which makes use of radio waves to transmit sounds captured by the microphone in the baby monitor.
These sounds are transmitted in the antenna of the baby monitor and is received through the antenna of the receiving parent unit. This device uses the same concept as antennas in mobile phones to transmit radio signals and is a useful tool as a two way communication. This device is often used to make sure a baby is safe and alert parents on any danger or incidents about to happen on the baby. This device is often used by parents to remotely listen or observe an otherwise unattended child. Air-craft bodyAntennas are placed on an aircraft or missile body for different communication.
Antenna placed at nose of the aircraft is a part of guidance RADAR system, which will guide the aircraft. Various jamming antenna are placed on different parts of aircraft for jamming the enemy signals. Antenna placed at the belly of the aircraft for data link application. Some these antennas placed at the body of the air-craft are operated on radio waves, so care should be taken that to avoid the interference of radiation pattern of all these antennas.Future projection on the impact of applications of antenna in mobile phonesInternal integrated antennas for mobile phonesInternal integrated antennas such as micro strip antennas significantly reduce the interaction between the cellular phone antenna and the human body. Some special configurations of micro strip antennas have a very small size and a good performance beside the human body. They could be sensitive to both vertically and horizontally polarized waves and their radiation patterns may have good isotropic characteristics.
Internal antennas could be integrated to the PCB (Printed Circuit Boards) and they could be easily shielded. Furthermore, internal antennas could be designed with a high isolation between the receiver and the transmit bands which makes the design of the duplexer much easier. Moreover, internal antennas are very rigid and they reduce the overall size of the phone.3D printed antennasWhen we talk on cellular phones, radio frequency is shared with everyone else who is using a mobile phone within a three-kilometre radius of the nearest base station.
This sharing doesn’t always work perfectly because is causes network congestion which can lead to static, dropped calls, and slow data downloads. One way 3D printing is about to influence the future of antennas is that traditionally-shaped antennas at lighter weights and cheaper costs are being designed and can be achieved through conventional manufacturing methods. These 3D-printed antennas are also notable because they tend to be more powerful than regular antennas. This way, users can have better reception as well as better mobile coverage when they are making phone calls.Antenna miniaturisationNew antennas that are between a tenth and a hundredth of the size of antennas that are currently on the market. What’s unique about these ultra-small antennas is that they communicate via radio waves faster, whereas normal-sized antennas are activated by radio waves at slower speed.
This mini-antennas is able to send and receive 2.5 GHz signals nearly 100,000 times more efficiently than a conventional ring antenna. This way, signals are sent and received by the antennas in our mobile phones faster and two way communication becomes more efficient. The effect of the human body on this antenna and also the effect of this antenna on the human is very small. Furthermore, the effect of the human body on the internal antenna will much lesser than its effect on the external antenna. This means that the SAR of the internal cellular phone antenna is much lower than the SAR of the external antenna.
On the other hand, the developed internal antenna can also be used in some other applications such as digital cordless phones, wireless modems and PCMCIA pager cards. Digital antennaDigital antennas can have even greater bandwidth, which leads to a higher data transfer speed and improved efficiency. Digital antennas may also dispose of the analogue components that traditional antennas use to tune into the desired frequency.
This facilitates antenna design and enables the creation of more compact antennas with better radiation efficiency. With antennas designed using the standard technology, it is possible to obtain either a broad frequency range or high efficiency, but not both at the same time. Antennas’ radiation efficiency has in recent times been falling because the frequency range used by mobile phones has been continuously increasing. Poor radiation efficiency leads to a short transmission range, for which network operators are then forced to compensate with a denser network of base stations. Energy is wasted in both the phone and the base station.
In addition, increasing the network density is expensive. Therefore, digital antenna is the best alternative in providing higher data transfer speed and improved efficiency. 3397 words (including literature review)ConclusionAs a conclusion, antennas in mobile phones brings about many benefits to the society. Antennas in mobile phones help speed up two-way communication making it faster and more efficient to communicate with friends and families despite the distance. Emergency calls can also be made to another person regardless of the distance between the caller and the receiver. Besides that, many new applications of radio waves in antennas are being discovered and is already in the process of development.
For instance, internal integrated antennas such as micro strip antennas significantly reduce the interaction between the cellular phone antenna and the human body. Some special configurations of micro strip antennas have a very small size and a good performance beside the human body. This makes the implementation of radio waves in many applications safer for mankind and therefore reducing the negative impacts on health. However, there are also some new applications that require the use of radio waves but at a broader frequency range like digital antennas. Hence, more radio frequency radiation will be released which brings about health hazard like cancer, biological effects, thermal effects and many more. Therefore, in future work, this drawback need to be encountered and solved in order for it to be established for wider application use of radio waves by antennas. ReferenceIto, K.
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1 Ampere’s lawRetrieved from (http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/amplaw.
html)Figure 1.1.2 Faraday’s lawRetrieved from (http://hyperphysics.phy-astr.gsu.
3 Lenz’s lawRetrieved from (http://hyperphysics.phy-astr.gsu.
edu/hbase/electric/farlaw.html)Figure 1.1.4 Gauss’s lawRetrieved from (http://hyperphysics.
5 Electromagnetic radio waves consist of vibrating electric waves (blue) and magnetic waves (red) traveling together at the speed of light (black arrow)Retrieved from (http://www.explainthatstuff.com/antennas.html)Figure 2.2.
1 Thermo graphic image of the head with no exposure to harmful mobile phone radiation (left) compared to thermo graphic image of the head after a 15 minute phone call (right). Yellow and red areas indicate thermal (heating) effects that can cause negative health effectsRetrieved from (https://www.uncommonwisdomdaily.com/cell-phone-radiation-could-be-changing-your-brain-20926)Figure 3.1.1 Sketch of a generic home healthcare system with a wireless implantable device working in a Wireless Body Area Network (WBAN)Retrieved from (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4934257/)Figure 3.1.2 Antennas as one of the system used for data telemetry Retrieved from (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4934257/)Figure 3.1.3 Wireless capsule endoscopyRetrieved from (https://ieeexplore.ieee.org/document/4227408/)