RADIO FREQUENCY Topics
Radio Frequency
The term “radio” refers to the transmission and reception of information over radio waves or radio frequency (RF). Heinrich Hertz was the first to generate radio waves with his experiments to confirm that electrical fields and magnetic fields can couple together to form electromagnetic waves. Radio waves are just one type of electromagnetic radiation across a spectrum of waves that vary in wavelength and frequency.
Hertz’ success in generating and detecting radio waves in the laboratory laid the foundation for understanding electromagnetic waves of electric and magnetic energy moving (radiating) through space at the speed of light, also referred to as electromagnetic radiation.
A radio wave is generated within an antenna by changing direction of electrons in a conductor back and forth creating an oscillating or alternating electric current. As the electric current in the antenna oscillates, it creates a changing electric field around the antenna. A changing electric field generates a changing magnetic field, and vice versa. The changing electric and magnetic fields propagate away from the antenna, forming an electromagnetic wave. The frequency of wave corresponds to the frequency of the oscillating electric current and if measured in Hertz units.
Radio frequency (RF) refers to the range of electromagnetic frequencies used in various wireless communication and broadcasting technologies. Radio waves and microwaves, which collectively are referred to as “radio frequency” or “RF” energy, have the longest wavelengths and the lowest frequencies in the electromagnetic spectrum and thereby have the lowest energy.
Electromagnetic Energy
Electromagnetic waves carry energy as they propagate through empty space and, depending on their properties, through various materials. The amount of energy is measured in units of electron volts (eV) and is directly proportional to the wave’s frequency and wavelength. Wavelength is the distance between the crests of a wave and frequency is the number of times a crest passes a point each second. Long wavelengths have a lower frequency and less energy than shorter waves. The shortest wavelengths have the highest frequencies and the most energy in the spectrum. The wavelength, frequency, and energy of an electromagnetic wave determine the unique properties of the wave and how it interacts with matter. Some parts of the spectrum are used for communication, others for imaging and sensing, and still others for scientific research and medical applications.
Electromagnetic Fields
Electromagnetic waves are composed of oscillating electric and magnetic fields and when combined, produce electromagnetic fields. Electric fields are produced by electric charges, such as electrons or protons, and exert a force on other charged objects within their vicinity. The strength of an electric field is measured in volts per meter (V/m). Magnetic fields are generated by moving electric charges or by the motion of electrons. Magnetic fields exert forces on other moving charged particles and can also affect magnetic materials like iron. When an electric field and a magnetic field oscillate in a synchronized manner, they create electromagnetic waves. Together, the electric fields and magnetic fields, create Electromagnetic fields (EMFs) the waves move through space. The strength of a magnetic field is measured in units called teslas (T) or gauss (G).
Ionizing vs Non-ionizing Radiation
Electromagnetic waves are also referred to as “radiation” because waves radiate from a source such as the sun or radioactive materials but not all radiation acts the same. There are two broad categories of radiation at the opposite ends of the electromagnetic spectrum: ionizing radiation and non-ionizing radiation, each with distinct characteristics and effects.
Ionizing radiation is what most people think of when they hear the word radiation. They might think of radiation associated with nuclear power plants or radiation therapy which can have an ionizing effect. Ionization is the process of removing one or more electrons from an atom or molecule, creating charged particles (ions). It requires large amounts of energy to overcome the binding forces that hold electrons in their orbits around the atomic nucleus. Ionizing radiation can carry more than a billion times more energy than non-ionizing radiation, enough energy to ionize atoms. Ionizing radiation, such as Gamma rays and x-rays, have the highest amounts of energy in the spectrum.
We are constantly exposed to low levels of ionizing radiation from natural sources. Earth’s atmosphere protects us from cosmic radiation, a natural source of radiation produced by stars and our sun that includes high-energy charged particles, x-rays, and gamma rays. Other natural sources of ionizing radiation include terrestrial radiation from the decay of radioactive materials in the earth (e.g., radon) and some building materials (e.g., concrete, sandstone, brick) that emit low levels of radiation. Exposure to these natural sources of ionizing radiation are typically at low levels. This means that the usual amount of ionizing radiation from natural sources absorbed by our bodies (dose) is small.
Non-ionizing radiation does not have enough energy to strip electrons from atoms or damage DNA or organic cell structures. Examples of non-ionizing radiation include visible light from the sun, thermal (heat) radiating from our bodies, and radio waves transmitting our favorite satellite radio stations.
The most familiar form of non-ionizing radiation is visible light. The different wavelengths and frequencies of visible light make up the colors of the rainbow or the visible light spectrum. Colors range in frequency from around 400 THz to 800 THz and have wavelengths between 400 and 750 nm. Colors with shorter wavelengths, like violet and purple, have a higher frequency and more energy. Longer wavelengths, like red, have a lower frequency and less energy.
RF Frequency is non-ionizing
Because RF radiation does not have the energy to ionize atoms, it is considered non-ionizing. RF radiation primarily interacts with charged particles (such as electrons) within the body by inducing oscillations in their motion. This interaction results in the absorption of RF energy as heat, but it does not produce ions or cause damage that is associated with ionizing radiation. The human body can absorb radio waves at various frequencies, but the extent to which absorption occurs depends on the frequency of the radio waves, the power of the signal, and the specific tissues involved.
Non-ionizing radiation, including RF radiation, is generally considered to have lower potential for causing immediate harm to biological tissues compared to ionizing radiation. However, safety guidelines and exposure limits have been established to protect individuals from potential adverse effects associated with excessive RF exposure, such as localized heating and thermal effects. These guidelines are set by regulatory bodies like the Federal Communications Commission (FCC) in the United States and the International Commission on Non-Ionizing Radiation Protection (ICNIRP).
WIRELESS TECHNOLOGY AND TELECOMMUNICATIONS
Wireless technology using Radio Frequency (RF) has been a fundamental part of our communication and entertainment landscape for over a century. Commercial AM radio started broadcasting in the 1920s and then FM radio in the 1930s. By the 1940s, television started broadcasting and expanded into rural areas in 1950s. We have been living a world where RF frequencies are all around us and have been broadcasted into our homes for decades before the adoption of cellular technology.
Evolution of wireless technology
The foundation of wireless communication was laid with the discovery of electromagnetic waves by scientists like Heinrich Hertz and James Clerk Maxwell in the late 19th century. This led to the development of wireless telegraphy, pioneered by Guglielmo Marconi. AM radio, which uses amplitude modulation to transmit audio signals, began broadcasts in the 1920s providing news, entertainment, and music to a growing audience.
Edwin Armstrong's invention of frequency modulation (FM) revolutionized radio broadcasting. FM radio offered clearer, static-free audio compared to AM radio because it was less susceptible to interference. FM radio stations expanded, offering a wider range of music and programming, leading to the development of stereo FM broadcasts in the 1950s, further enhancing audio quality.
Early television broadcasts also used radio frequencies for transmitting both audio and video signals which were displayed in black-and-white using cathode-ray (CRT) technology. There were only a handful of television stations operating in major cities, and coverage was limited primarily to urban areas. By the 1960s, the popularity of television exploded and had become a mainstream form of entertainment and information. The number of television stations had expanded significantly with multiple regional and local stations had also multiplied to serve a growing and diverse audience.
By the 1980s, cellular technology using RF technology for communications started gaining momentum. Cellular technology allowed for mobile voice communication and later data services, revolutionizing the way people communicate and access information. Some of most essential uses of wireless communications include emergency response and satellite navigation using GPS (Global Positioning System) satellites. RF technology for wireless communications continued to evolve with the development of Wi-Fi, Bluetooth, satellite navigation and other wireless communication standards that have become integral to our daily lives.
Throughout this history, RF frequencies have indeed been all around us, serving as the foundation for various forms of wireless communication and entertainment. They have connected people, provided information, and shaped the way we live and interact with the world. The adoption of cellular technology represented a significant milestone in this ongoing evolution, as it brought personal communication devices into the mainstream and paved the way for the digital age.
Characteristics of radio waves for telecommunications
Like all electromagnetic waves, radio waves can travel through the vacuum of space at the speed of light. But unlike many other forms of electromagnetic waves, RF signals are capable of penetrating the Earth's atmosphere without significant signal degradation. They can tolerate various forms of interference, such as atmospheric conditions and signal blockage by objects making RF suitable for maintaining reliable communication as satellites move through different orbits, altitudes, and positions relative to the Earth's surface.
RF signals can transport a large amount of data at a very fast rate over large distances. This speed allows for virtually instantaneous communication between Earth and satellites and between transmitters and receivers within a cellular network. RF antennas can be designed to focus and direct signals accurately toward specific targets. This directional control helps establish a strong and stable connection between ground stations and satellites, even in the presence of interference or other sources of RF noise. Radio waves are also suitable for long-distance communication because they can be propagated over the Earth's curvature, which is essential for global communication via satellites.
Radio frequency communication encompasses a wide range of frequencies that can support various data rates and provide different frequency bands to accommodate a wide range of applications, from simple telemetry and command signals to high-data-rate data transmission for applications like satellite television and broadband internet.
The characteristics of radio waves makes them an ideal for telecommunications and wireless technology. RF frequency is a reliable and versatile for communicating with satellites. The ability to transmit signals at the speed of light, adapt to various frequencies and conditions, and offer directional control makes RF an essential technology for the successful operation of satellites in space.
RF Exposure and Safety Guidelines
The safe levels for exposure to radiofrequency (RF) energy depend on several factors, including the frequency of the RF radiation, the duration of exposure, and the power density of the RF signal. Since RF energy is used in various technologies, including wireless communication devices, microwave ovens, and medical equipment, standards have been established to ensure public safety and environmental health. Studies have shown that environmental levels of RF energy routinely encountered by the general public are typically far below levels necessary to produce significant heating and increased body temperature. In some occupational settings, such as work environments near high-powered RF sources, exposures can exceed the recommended limits.
In the United States, the Federal Communications Commission (FCC) has adopted safety guidelines for limiting the RF environmental exposure exposure for different frequency ranges. While the FCC has jurisdiction over RF technology including the authorization and licensing of devices, transmitters, and facilities that generate RF radiation, it does not have primary jurisdiction regarding health and safety and relies on other agencies and organizations.
Federal health and safety agencies, such as the Environmental Protection Agency, EPA, U.S. Food and Drug Administration (FDA), the National Institutes of Health (NIH), the National Institute for Occupational Safety and Health (NIOSH) and the Occupational Safety and Health Administration (OSHA) have also been involved in monitoring and investigating issues related to RF exposure.
The FDA states that the “current limit on radio frequency (RF) energy set by the Federal Communications Commission remains acceptable for protecting the public health.” And based on FDA’s evaluation, “the weight of scientific evidence has not linked exposure to radio frequency energy from cell phone use with any health problems at or below the radio frequency exposure limits set by the FCC.” The NIH National Cancer Institute concludes that “no consistent evidence for an association between any source of non-ionizing EMF and cancer has been found.”
The FCC's exposure guidelines specify limits for human exposure to RF emissions are designed to protect against both thermal (heating) and non-thermal (non-heating) effects of RF radiation. These limits are expressed in terms of Specific Absorption Rate (SAR), a measure of the rate of absorption of RF energy by the body. The specific limits vary depending on the frequency range and the intended use of the RF-emitting device. For example, the safe limit for a mobile phone user is an SAR of 1.6 watts per kg (1.6 W/kg), averaged over one gram of tissue, and compliance with this limit must be demonstrated before FCC approval is granted for marketing of a phone in the United States. See Specific Absorption Rate (SAR) for Cellular Telephones for more information regarding SAR and cellphones.
For more information about studies on the environmental and health effects from exposure to RF radiation, visit the Research section of this site [link to Research page].
Cell Phones Topics
Imagine making a cell phone call to a friend in another country. You dial their number and wait for your friend to pick up, and then you have a conversation in real time with very little delay. That is because your voice - or data from your phone - is being transmitted to your friend over electromagnetic waves that travel at the speed of light. This technology not only allows you to text your favorite picture to your friend, but is essential for emergency services, disaster response, and even providing phone service in developing countries that do not have extensive infrastructure for land lines.
How Cell Phones work
Cell phones converts your voice into digital signals and transmits this information over radio frequencies to a cellular network which then transmits the data to its destination. Just as radios and televisions use antennas to receive signals from a local broadcast station, cell phones use antennas which receive signals from the closest cell tower. In both examples, these antennas receive radio frequency (RF) radiation that is in the non-ionizing portion of the electromagnetic spectrum. RF radiation is hundreds of thousands of times less energy than ionizing radiation, (i.e., x-rays or gamma rays), and have very low frequencies and long wavelengths which can pass through clouds, rain, smoke, dust, and other atmospheric interference. This characteristic of RF waves make them perfect for wireless communications.
When you talk into a cell phone, the microphone converts your voice into a pattern of electronic signals and then a microchip converts them into a string of numbers. The cell phone’s antenna transmits this digital information using RF waves to a receiving antenna on another cell phone which converts your digitized voice patterns back into sound through the phone’s speaker.
A cell phone antenna emits low-levels of RF radiation that is not powerful enough to send signals very far. To get your call to your destination, the cell phone automatically communicates with the closest antenna in a cellular network. These more powerful antennas are located on top of towers or masts and geographically located in a network of cells. Like all electromagnetic energy, RF signals get weaker the further you get from the source. The greater the distance a cell phone is from an antenna, the greater the power the cell phone needs to use for its signal to reach the tower. A cell phone varies its power output when connecting to a cell tower based on the distance between the phone and the tower.
Cellular networks use a feature called "power control" to manage the transmission power of mobile devices to ensure that the mobile device's signal is strong enough for reliable communication with the cell tower while minimizing interference with neighboring cells and conserving battery life. Your cell phone continuously monitors the signal strength and quality of the connection. If the signal weakens or gets stronger your phone adjusts its transmit power accordingly to maintain a reliable connection.
When your cell phone is in close proximity to a cell tower (i.e., you have a strong signal), it reduces the power needed to transmit because it doesn't need to use high power to reach the nearby tower since the signal doesn't have to travel a long distance. Lowering the power helps conserve your phone's battery and reduces the risk of interference with other devices on the same frequency.
When your cell phone is far away from the nearest cell tower (i.e., you have a weak signal), it increases its transmit power. This is necessary because the signal must overcome greater path loss due to the increased distance. By boosting its power output, your phone attempts to establish a reliable connection with the tower and ensure that your call or data transmission is successful. A cell phone with a weak signal emits higher power and slightly increase the exposure to RF radiation, but power levels are still well within the regulated RF exposure limits.
Measuring RF Radiation
Radio waves are electromagnetic waves with very low frequencies and therefore very low energy in comparison to higher energy wavelengths that have so much energy they can ionize an atom by knocking out an electron or damage organic cells. Electromagnetic radiation can be described by frequency, wavelength or energy but can also vary in power. Power refers to the rate at which energy is transferred, used, or produced.
Since an electromagnetic wave has both an electric and a magnetic component and can be measured by the strength of the electric field in units of “volts per meter” (V/m) or the strength of the magnetic field in units of “amperes per meter” (A/m). A measurement of the total strength of the electromagnetic field is called power density. Power density is the power flow (watts) per unit area (square meter) and is used to express the intensity of exposure.
Non-ionizing radio frequencies with lower energy can be generated at higher power densities. which can cause heating of skin tissue. Exposure to high levels of RF radiation can generate heat in biological tissues, a phenomenon known as thermal effects. When exposure levels are high enough, excessive heating of tissues can occur, potentially causing burns or other thermal injuries. For example, microwave ovens use very high-power densities of microwaves to heat food but the casing of the oven prevent the radiation from escaping the oven. Regulatory limits are set to prevent harmful thermal effects in everyday consumer devices.
Measuring RF Radiation Exposure
Specific Absorption Rate (SAR) is a measure of the rate at which electromagnetic energy is absorbed by the human body when exposed to radiofrequency (RF) electromagnetic fields. SAR is typically used to assess the potential health risks associated with the use of devices that emit RF radiation, such as mobile phones, wireless routers, and microwave ovens. It is expressed in watts per kilogram (W/kg) and represents the amount of RF energy absorbed per unit mass of body tissue over a specific time period.
Cell phones can have different SAR levels and manufacturers are required to report the maximum SAR level of their product to the US Federal Communications Commission (FCC). The SAR value of a cellular phone can be search through the FCC ID database using the device’s FCC ID number. According to FCC safety guidelines, the upper limit of SAR allowed in the United States is 1.6 watts per kilogram (W/kg) of body weight. See Specific Absorption Rate (SAR) for Cellular Telephones for more information regarding SAR and cellphones.
Safety Guidelines for Cell Phones
The FCC is required by the National Environmental Policy Act of 1969 to evaluate the effect of emissions from FCC-regulated transmitters on the quality of the human environment. Several organizations, such as the American National Standards Institute (ANSI), the Institute of Electrical and Electronics Engineers, Inc. (IEEE),and the National Council on Radiation Protection and Measurements (NCRP) have issued recommendations for human exposure to RF electromagnetic fields.
Cell phones emit low levels of non-ionizing radiation while in use. The type of radiation emitted by cell phones is also referred to as radio frequency (RF) energy. As stated by the National Cancer Institute, "there is currently no consistent evidence that non-ionizing radiation increases cancer risk in humans. The only consistently recognized biological effect of radiofrequency radiation in humans is heating." To induce heating from RF energy, exposures would have to be well beyond the current safety limits.
Public exposure to RF radiation from cell phones and cell towers is well below the limits set by international guidelines and standard setting organizations. But in comparison to cell towers, an individual’s RF exposure is primarily from their cell phone. While there is no established health benefit from reducing an individual’s RF exposure from cell phones, there are simple action to reduce that exposure. One can reduce the amount of time spent using a cell phone; use speaker mode, head phones, or ear buds to place more distance between your head and the cell phone; avoid making calls when the signal is weak as this causes cell phones to boost RF transmission power, and use text functions rather that voice.
Microwaves are a subset of radio frequencies and are used for a variety of wireless applications. While cell phones are designed to emit RF radiation at much lower power levels, typically around 0.2 to 2 watts (200 to 2000 milliwatts) or less. These power levels are far too low to generate the significant heat required for cooking food or causing harm to biological tissues. However, microwave ovens are designed to produce higher power densities of microwave radiation, typically in the range of 600 to 1,200 watts or more, enough intensity to cook food.
Microwave ovens work by exposing food to high levels of microwaves but don’t escape the metal enclosure – that is why microwaves will not work if the door is open. There are strict standards to ensure radiation emissions do not pose a health hazard. Inside the oven, microwaves are absorbed by rotating molecules in the food which causes just the food to heat up and not the oven cavity. It is the interaction and rotation of the water or fat molecules that creates heat to cook the food, not the microwave radiation. That is why food higher in water or fat content heats up faster.
CELLULAR NETWORKS & CELL TOWERS
A cellular network is a telecommunications network that enables mobile communication using cell phones and other wireless devices. It's called a "cellular" network because the coverage area is divided into small geographic regions called "cells." Each cell is served by a base station, also known as a cell tower or cell site, equipped with antennas and transceivers. These cells are interconnected to provide seamless communication as you move from one cell's coverage area to another.
Cell Towers and Base Stations
Base stations typically contain antennas, control electronics, a GPS receiver for timing, digital signal processors, radio transmitters and power sources. The antennas are usually located outdoors on rooftops, sides of buildings, towers or monopole structures. There is one antenna used to transmit radio frequency (RF) signals to cellphones, and the other two used to receive RF signals from cellphones.
The cell tower receives your signals, processes them, and forwards them to the base station, which is usually connected to a central mobile switching center (MSC). The MSC connects your call to the appropriate destination, whether it's another mobile phone, a landline phone, or a networked device. It also manages tasks like call routing, handovers between cells, and call setup. The recipient's phone or device receives the incoming call signal.
RF Exposure
Cell phone communication is two-way. Both your cell phone and the cell tower are transmitting and receiving radiofrequency (RF) signals. Given that a phone is closer to the body than the base station, the most exposure attributable to RF emissions is from the phone. The phone also varies its power output to both maintain the best cell connection and to conserve battery.
Like all electromagnetic energy, RF signals get weaker the further you get from the source. The greater the distance a cell phone is from an antenna, the greater the power the cell phone needs to use for its signal to reach the tower. There is more RF exposure to cell-phone users when cell towers are widely spaced. When phone users are close to towers, the cell phone uses less power to emit its signal, which means less RF exposure to the cell phone user. Each user’s total exposure to RF is due primarily to their own phone’s emissions — an exposure that actually increases when the cell towers get farther apart.
It is possible, however, to have measurable exposure from a base station depending on how close you are to the station, its power rating and the direction the antenna’s beam. At very high levels, RF waves can be absorbed by the body and converted into heat when if exposed to large enough amounts. Based on current published scientific studies, there is no strong evidence that exposure to radiofrequency (RF) waves near cell phone towers causes health effects. RF waves used by cell phones to communicate with nearby cell towers are non-ionizing, meaning they are not a form of energy that can ionize atoms or cause DNA damage in human cells. The potential for tissue heating is the only established mechanism of interaction associated with potentially adverse effects. [link to Research section]
Exposure guidelines and standards
Exposure guidelines and standards for RF levels establish exposure limits to protect against adverse outcomes that could result from such heating. The human body can absorb RF waves in a frequency range known as the "Resonance Absorption Frequency" or "Resonant Frequency." This frequency range typically falls between ~70 and 110 MHz. As the frequency of radio waves increases, the absorption by the human body decreases. Exposure to radio frequency levels below established guidelines result in negligible temperature rise in the human body.
Regulatory authorities such as the US Federal Communication Commission (FCC) set the limits for safe exposure to RF based on published scientific data. At ground level near typical cellular tower, the amount of energy from RF waves is hundreds to thousands of times less than that set by the US FCC.
Generations of Cellular Networks
Cellular networks have evolved through several generations primarily because of the need for continuous improvement and adaptation to meet evolving technology, user demands, and new use cases. Each generation refer to a set of protocols for how information is transmitted over radio waves. Early generations were analog and have since evolved to digital. Capabilities were incorporated into each new generation to meet the growing needs for telecommunications such as increased network capacity to accommodate more used and higher data traffic. Increased data speed helped minimize latency and supported new services beyond voice calls. Energy efficiency, security, and global standardization also contributed to the evolution of networks.
New generations also optimize the use of available frequency spectrum, making more efficient use of the radio frequencies allocated for wireless communication. The newest generation is 5G which began rolling out in the late 2010s. There were six earlier generations beginning with 1G in the 1980s.
Fifth Generation (5G) Cellular network
5G, or fifth generation, is the latest wireless mobile phone technology and was first widely deployed in 2019. 5G antennas are designed to support the unique characteristics and requirements of 5G technology, including higher data speeds, lower latency, and the ability to connect a massive number of devices. In addition to traditional sub-6 GHz frequency bands, 5G utilizes mmWave spectrum with much higher frequencies and shorter wavelengths than previous generations.
As the high frequency waves used by 5G can provide extremely high data speeds, more infrastructure is required due to their shorter range and limited penetration through obstacles. To compensate for the shorter range of mmWave signals and to improve signal penetration through obstacles, more, but smaller mmWave versions of the base stations and antennas are needed.
These antennas are often smaller and more numerous than traditional macrocell antennas and are used to provide dense urban coverage. Some antennas have a higher antenna gain that can concentrate signal power in specific directions. Many 5G antennas incorporate advanced beamforming and Massive MIMO (Multiple-Input Multiple-Output) technology. Beamforming allows antennas to focus signals in specific directions, enhancing signal strength and reducing interference. Massive MIMO uses multiple antenna elements to improve coverage and capacity. The combination of beamforming, Massive MIMO, and advanced antenna technologies enhance the potential of 5G.
5G Health Concerns and Standards
Fifth generation (5G) mmWaves have higher frequencies than previous generations of cellular networks, but they are still in the non-ionizing radio frequency portion of the spectrum and do not have enough energy to ionize atoms or cause damage to the DNA of cells. Transmitted signals at higher frequencies in the range of 30 GHz or 30,000 MHz have considerable difficulty in penetrating most materials. Just as mmWaves can’t penetrate leaves on trees they also can’t penetrate human skin. Additionally, 5G networks have lower power and use small cells with short-range base stations. Public exposure levels are generally well below the exposure limits set by international guidelines and standard setting organizations. [link to Standards?]
Scientists and engineers from two organizations, the National Council on Radiation Protection and Measurements (NCRP) and the Institute of Electrical and Electronics Engineers (IEEE) extensively reviewed the scientific literature on the biological effects of the radiofrequency (RF) waves used in 5G and established safety guidelines, which have been strictly adopted by the US Federal Communication Commission (FCC). If the recommended safety levels are observed, there should be no consequence to public health by living closer to 5G tower base stations.
Findings from a 2020 study in the Journal of Health Physics by the IEEE Engineering in Medicine and Biology Society Committee on Man and Radiation (COMAR) suggest that the added transmission signals from multiple small 5G antennas and base stations will most likely not change the overall levels of public exposure to RF radiation. Overall, public exposure levels are expected to generally remain well below the exposure limits set by international guidelines and standard setting organizations including those of the IEEE and ICNIRP (International Commission on Non-ionizing Radiation Protection). Richard Tell, committee chair and co-author, concludes that “in fact, an individual’s personal exposure will continue to be dominated from the uplink signals originating from one’s own wireless device as is the case now.”
RF DEVICES Topics
Wi-Fi Networks
Wi-Fi, short for "Wireless Fidelity," is a technology that enables devices to connect to the internet or communicate with each other wirelessly over a local area network (LAN). It has become an integral part of modern life and is commonly used in homes, businesses, schools, and public places like cafes and airports.
Wi-Fi operates using radio frequencies within the 2.4 GHz and 5 GHz bands, which are unlicensed and open for public use. These frequencies allow multiple devices to use Wi-Fi without significant interference.
Online gaming consoles, streaming devices, and smart speakers commonly use Wi-Fi to access online gaming services, stream content, and receive software updates. Many smartphones can act as Wi-Fi hotspots, allowing other devices to connect to the internet through the phone's cellular data connection. This is especially useful when traveling or in areas with limited wired internet infrastructure.
Wi-Fi exposure from wireless local area networks (WiFi), whether in schools, public buildings, or home is common and is thousands of times lower than the regulatory limits. While there are not a large number of laboratory studies or studies on humans exposure to Wi-Fi, those that have been done do not provide any meaningful support for potential health harm in the form of sleep disturbance, symptoms such as headaches or fatigue, or physiologic effects such as changes in blood pressure or heart rate. [link to Research section]
Bluetooth Devices
Bluetooth technology operates in the 2.4 GHz frequency range and allows electronic devices to connect and exchange data over short distances, typically within a range of about 10 meters (30 feet), without the need for cables. Bluetooth devices provide a convenient and efficient way to communicate wirelessly between devices.
Popular wireless devices such as headphones, earbuds, speakers, keyboards, game controllers, and printers use Bluetooth to connect wirelessly to smartphones and computers.
Bluetooth technology is also used for hands-free communication in cars to allow drivers to make and receive calls, access navigation, and control audio systems without taking their hands off the steering wheel.
Bluetooth can be used to synchronize data between devices such as transferring contacts, calendars, and other information between a smartphone and a laptop. Various health and fitness gadgets, like watches, fitness trackers, and smart scales use Bluetooth to synchronize data with other devices for analysis and tracking.
Satellite Navigation and GPS
Satellite navigation systems, like the Global Positioning System (GPS), use radio frequency signals to determine the precise location, speed, and time information for users on Earth's surface. GPS consists of a constellation of satellites orbiting the Earth. As of my last knowledge update in September 2021, there were approximately 30 operational GPS satellites. These satellites are positioned in specific orbits, usually at altitudes of approximately 20,000 kilometers (12,000 miles).
Each GPS satellite continuously broadcasts radio frequency (RF) signals in the microwave band. These signals contain precise timing and positioning information. GPS receivers are used in smartphone, vehicles, and navigation devices to receive signals from multiple GPS satellites simultaneously. To determine its position, the GPS receiver combines the distance measurements and the timing information from multiple satellites to calculate its latitude, longitude, altitude, and other information like speed and heading.
Common GPS receivers operate at a frequency of approximately 1.57542 GHz and can receive a GPS satellite's identity and the precise time the signal was transmitted. GPS receivers that operate around 1.2276 GHz are used for more advanced applications such as military use and scientific research requiring additional information to improve accuracy.
Satellite Radio and Television
Satellite radio and satellite television services use distinct radio frequency bands and satellite systems for their transmissions. Satellite radio focuses on audio content and operates in the S band, while satellite television services provide a wide range of video and audio content and use higher-frequency bands such as the Ku band and C band.
Satellite radio services, like SiriusXM in North America, use a specific radio frequency band known as the S-band. This band encompasses frequencies between 2.3 GHz (gigahertz) and 2.4 GHz. Satellite radio services rely on a constellation of geostationary or geosynchronous satellites positioned in orbit around the Earth. These satellites are placed at specific positions in the sky, ensuring that they remain fixed relative to the Earth's surface.
Satellite television services, such as DIRECTV and DISH Network in the United States, use higher frequencies than satellite radio. These services typically operate in the Ku band (11.7 GHz to 12.7 GHz) for downlink signals (from the satellite to the receiver) and the C band (3.7 GHz to 4.2 GHz) for uplink signals (from the receiver to the satellite). Satellite TV services use multiple satellites in geostationary orbits to provide coverage over a wide geographic area. Customers typically require a satellite dish and receiver to receive and decode the television signals.
Remote Control devices
Radio remote controllers, commonly used for various applications such as remote-controlled vehicles, industrial machinery, and home automation, use radio frequency to connect wirelessly. Radio Controlled (RC) remotes are used for operating remote-controlled vehicles, drones, and toys. Radio Frequency (RF) remote controls for home automation systems, smart home hubs, and some gaming consoles use radio waves to communicate. RF provides longer-range and more reliable communication compared to infrared light used in common television remote.
The specific frequency used by a remote controller may vary depending on factors such as the intended application, region, regulations and allocation of frequency bands. The exact frequencies can vary, but the following frequency bands are commonly used for radio remote controllers:
- 27 MHz Band: This frequency band is widely used for radio-controlled toys and low-power applications. It’s often used for basic radio-controlled cars and toys.
- 49 MHz Band: Similar to the 27 MHz band, the 49 MHz band is also used for radio-controlled toys, including toy cars and simple remote control systems.
- 72 MHz Band: This frequency band is commonly used for hobby-grade radio-controlled aircraft and helicopters. It offers more channels and allows for greater control precision.
- 2.4 GHz Band: The 2.4 GHz band is one of the most popular frequency bands for radio remote controllers, especially for hobby-grade and consumer-grade applications. It provides a wide range of channels, reduces interference, and allows for more complex control systems. It’s commonly used for RC cars, drones, boats, and more.
- 433 MHz Band: In some regions, the 433 MHz band is used for low-power radio remote control systems. It’s commonly used in home automation and industrial applications.
- 900 MHz Band: This frequency band is utilized for long-range industrial remote control applications. It provides greater range compared to higher-frequency bands but may have limited channels available.
- UHF Bands (Ultra-High Frequency): Frequencies in the UHF range, typically between 300 MHz and 3 GHz, are used for various industrial, military, and professional remote control applications. These bands offer good range and penetration through obstacles.
- VHF Bands (Very High Frequency): Frequencies in the VHF range, usually between 30 MHz and 300 MHz, are used for some specialized remote control systems, particularly in industrial and military settings.
- 3.4 GHz Band: This band is less common but is used in some advanced RC systems. It offers a good balance between range and interference resistance
Smart Meters
Smart meters are devices used to measure and monitor electricity, gas, or water consumption in homes and businesses. They use radio frequency (RF) radiation as a means of communication to send consumption data to utility companies or local service providers. Smart meters are equipped with sensors and measurement capabilities to record the consumption of utilities, such as electricity, gas, or water. At regular intervals, the smart meter uses RF radiation to transmit the collected data. This transmission is typically done in short bursts or packets of data at 900 MHz, 2.4 GHz, and 5.8 GHz radio frequencies.
Radio-Frequency Identification
Radio-Frequency Identification (RFID) is a technology that uses radio frequency signals to identify, track, and manage objects, animals, or people. It is commonly used in various applications, such as inventory management, access control, contactless payment systems, and supply chain logistics.
RFID systems consist of tags or transponders and RFID readers or interrogators. RFID tags are small electronic devices that contain a microchip and an antenna. These tags come in various forms, including stickers, cards, and key fobs. RFID readers are devices that send out radio frequency signals to interact with RFID tags. When an RFID reader emits radio waves, RFID tags within range of the reader receive this energy and use this energy to power up and transmit their stored data back to the reader. Data can include unique identification numbers, sensor readings, or other information stored on the tag.
RFID technology operates in various frequency bands, and the choice of frequency depends on the specific application and requirements. The choice of frequency band depends on factors such as the required read range, interference considerations, and regulatory requirements in a specific region.
