Wi-Fi is technology for radio wireless local area networking of devices based on the IEEE 802.11 standards. Wi‑Fi is a trademark of the Wi-Fi Alliance, which restricts the use of the term Wi-Fi Certified to products that complete after many years of testing the 802.11 committee interoperability certification testing. Devices that can use Wi-Fi technologies include, among others and laptops, video game consoles and tablets, smart TVs, digital audio players, digital cameras and drones. Wi-Fi compatible devices can connect to the Internet via a wireless access point; such an access point has a range of about 20 meters indoors and a greater range outdoors. Hotspot coverage can be as small as a single room with walls that block radio waves, or as large as many square kilometres achieved by using multiple overlapping access points. Different versions of Wi-Fi exist, with radio bands and speeds. Wi-Fi most uses the 2.4 gigahertz UHF and 5 gigahertz SHF ISM radio bands. Each channel can be time-shared by multiple networks.
These wavelengths work best for line-of-sight. Many common materials absorb or reflect them, which further restricts range, but can tend to help minimise interference between different networks in crowded environments. At close range, some versions of Wi-Fi, running on suitable hardware, can achieve speeds of over 1 Gbit/s. Anyone within range with a wireless network interface controller can attempt to access a network. Wi-Fi Protected Access is a family of technologies created to protect information moving across Wi-Fi networks and includes solutions for personal and enterprise networks. Security features of WPA have included stronger protections and new security practices as the security landscape has changed over time. In 1971, ALOHAnet connected the Hawaiian Islands with a UHF wireless packet network. ALOHAnet and the ALOHA protocol were early forerunners to Ethernet, the IEEE 802.11 protocols, respectively. A 1985 ruling by the U. S. Federal Communications Commission released the ISM band for unlicensed use.
These frequency bands are the same ones used by equipment such as microwave ovens and are subject to interference. In 1991, NCR Corporation with AT&T Corporation invented the precursor to 802.11, intended for use in cashier systems, under the name WaveLAN. The Australian radio-astronomer Dr John O'Sullivan with his colleagues Terence Percival, Graham Daniels, Diet Ostry, John Deane developed a key patent used in Wi-Fi as a by-product of a Commonwealth Scientific and Industrial Research Organisation research project, "a failed experiment to detect exploding mini black holes the size of an atomic particle". Dr O'Sullivan and his colleagues are credited with inventing Wi-Fi. In 1992 and 1996, CSIRO obtained patents for a method used in Wi-Fi to "unsmear" the signal; the first version of the 802.11 protocol was released in 1997, provided up to 2 Mbit/s link speeds. This was updated in 1999 with 802.11b to permit 11 Mbit/s link speeds, this proved to be popular. In 1999, the Wi-Fi Alliance formed as a trade association to hold the Wi-Fi trademark under which most products are sold.
Wi-Fi uses a large number of patents held by many different organizations. In April 2009, 14 technology companies agreed to pay CSIRO $1 billion for infringements on CSIRO patents; this led to Australia labeling Wi-Fi as an Australian invention, though this has been the subject of some controversy. CSIRO won a further $220 million settlement for Wi-Fi patent-infringements in 2012 with global firms in the United States required to pay the CSIRO licensing rights estimated to be worth an additional $1 billion in royalties. In 2016, the wireless local area network Test Bed was chosen as Australia's contribution to the exhibition A History of the World in 100 Objects held in the National Museum of Australia; the name Wi-Fi, commercially used at least as early as August 1999, was coined by the brand-consulting firm Interbrand. The Wi-Fi Alliance had hired Interbrand to create a name, "a little catchier than'IEEE 802.11b Direct Sequence'." Phil Belanger, a founding member of the Wi-Fi Alliance who presided over the selection of the name "Wi-Fi", has stated that Interbrand invented Wi-Fi as a pun on the word hi-fi, a term for high-quality audio technology.
Interbrand created the Wi-Fi logo. The yin-yang Wi-Fi logo indicates the certification of a product for interoperability; the Wi-Fi Alliance used the advertising slogan "The Standard for Wireless Fidelity" for a short time after the brand name was created. While inspired by the term hi-fi, the name was never "Wireless Fidelity"; the Wi-Fi Alliance was called the "Wireless Fidelity Alliance Inc" in some publications. Non-Wi-Fi technologies intended for fixed points, such as Motorola Canopy, are described as fixed wireless. Alternative wireless technologies include mobile phone standards, such as 2G, 3G, 4G, LTE; the name is sometimes written as WiFi, Wifi, or wifi, but these are not approved by the Wi-Fi Alliance. IEEE is a separate, but related organization and their website has stated "WiFi is a short name for Wireless Fidelity". To connect to a Wi-Fi LAN, a computer has to be equipped with a wireless network interface controller; the combination of computer and interface controllers is called a station.
A service set is the set of all the devices associated with a particular Wi-Fi network. The service set can be local, extended or mesh; each service set has an associated identifier, the 32-byte Service Set Identifier, which identifies the partic
In radio, multiple-input and multiple-output, or MIMO, is a method for multiplying the capacity of a radio link using multiple transmission and receiving antennas to exploit multipath propagation. MIMO has become an essential element of wireless communication standards including IEEE 802.11n, IEEE 802.11ac, HSPA+, WiMAX, Long Term Evolution. More MIMO has been applied to power-line communication for 3-wire installations as part of ITU G.hn standard and HomePlug AV2 specification. At one time, in wireless the term "MIMO" referred to the use of multiple antennas at the transmitter and the receiver. In modern usage, "MIMO" refers to a practical technique for sending and receiving more than one data signal over the same radio channel by exploiting multipath propagation. MIMO is fundamentally different from smart antenna techniques developed to enhance the performance of a single data signal, such as beamforming and diversity. MIMO is traced back to 1970s research papers concerning multi-channel digital transmission systems and interference between wire pairs in a cable bundle: AR Kaye and DA George and Wyner, W. van Etten.
Although these are not examples of exploiting multipath propagation to send multiple information streams, some of the mathematical techniques for dealing with mutual interference proved useful to MIMO development. In the mid-1980s Jack Salz at Bell Laboratories took this research a step further, investigating multi-user systems operating over "mutually cross-coupled linear networks with additive noise sources" such as time-division multiplexing and dually-polarized radio systems. Methods were developed to improve the performance of cellular radio networks and enable more aggressive frequency reuse in the early 1990s. Space-division multiple access uses directional or smart antennas to communicate on the same frequency with users in different locations within range of the same base station. An SDMA system was proposed by Richard Roy and Björn Ottersten, researchers at ArrayComm, in 1991, their US patent describes a method for increasing capacity using "an array of receiving antennas at the base station" with a "plurality of remote users."
Arogyaswami Paulraj and Thomas Kailath proposed an SDMA-based inverse multiplexing technique in 1993. Their US patent described a method of broadcasting at high data rates by splitting a high-rate signal "into several low-rate signals" to be transmitted from "spatially separated transmitters" and recovered by the receive antenna array based on differences in "directions-of-arrival." Paulraj was awarded the prestigious Marconi Prize in 2014 for "his pioneering contributions to developing the theory and applications of MIMO antennas.... His idea for using multiple antennas at both the transmitting and receiving stations –, at the heart of the current high speed WiFi and 4G mobile systems – has revolutionized high speed wireless."In an April 1996 paper and subsequent patent, Greg Raleigh proposed that natural multipath propagation can be exploited to transmit multiple, independent information streams using co-located antennas and multi-dimensional signal processing. The paper identified practical solutions for modulation, coding and channel estimation.
That year Gerard J. Foschini submitted a paper that suggested it is possible to multiply the capacity of a wireless link using what the author described as "layered space-time architecture."Greg Raleigh, V. K. Jones, Michael Pollack founded Clarity Wireless in 1996, built and field-tested a prototype MIMO system. Cisco Systems acquired Clarity Wireless in 1998. Bell Labs built a laboratory prototype demonstrating its V-BLAST technology in 1998. Arogyaswami Paulraj founded Iospan Wireless in late 1998 to develop MIMO-OFDM products. Iospan was acquired by Intel in 2003. V-BLAST was never commercialized, neither Clarity Wireless nor Iospan Wireless shipped MIMO-OFDM products before being acquired. MIMO technology has been standardized for wireless LANs, 3G mobile phone networks, 4G mobile phone networks and is now in widespread commercial use. Greg Raleigh and V. K. Jones founded Airgo Networks in 2001 to develop MIMO-OFDM chipsets for wireless LANs; the Institute of Electrical and Electronics Engineers created a task group in late 2003 to develop a wireless LAN standard delivering at least 100 Mbit/s of user data throughput.
There were two major competing proposals: TGn Sync was backed by companies including Intel and Philips, WWiSE was supported by companies including Airgo Networks and Texas Instruments. Both groups agreed that the 802.11n standard would be based on MIMO-OFDM with 20 MHz and 40 MHz channel options. TGn Sync, WWiSE, a third proposal were merged to create what was called the Joint Proposal. In 2004, Airgo became the first company to ship MIMO-OFDM products. Qualcomm acquired Airgo Networks in late 2006; the final 802.11n standard supported speeds up to 600 Mbit/s and was published in late 2009. Surendra Babu Mandava and Arogyaswami Paulraj founded Beceem Communications in 2004 to produce MIMO-OFDM chipsets for WiMAX; the company was acquired by Broadcom in 2010. WiMAX was developed as an alternative to cellular standards, is based on the 802.16e standard, uses MIMO-OFDM to deliver speeds up to 138 Mbit/s. The more advanced 802.16m standard enables download speeds up to 1 Gbit/s. A nationwide WiMAX network was built in the United States by Clearwire, a subsidiary of Sprint-Nextel, covering 130 million points of presence by mi
A whip antenna is an antenna consisting of a straight flexible wire or rod. The bottom end of the whip is connected to transmitter; the antenna is designed to be flexible so that it does not break and the name is derived from the whip-like motion that it exhibits when disturbed. Whip antennas for portable radios are made of a series of interlocking telescoping metal tubes, so they can be retracted when not in use. Longer ones, made for mounting on vehicles and structures, are made of a flexible fiberglass rod around a wire core and can be up to 35 ft long; the length of the whip antenna is determined by the wavelength of the radio waves it is used with. The most common type is the quarter-wave whip, one-quarter of a wavelength long. Whips are the most common type of monopole antenna, are used in the higher frequency HF, VHF and UHF radio bands, they are used as the antennas for hand-held radios, cordless phones, walkie-talkies, FM radios, boom boxes, Wi-Fi enabled devices, are attached to vehicles as the antennas for car radios and two-way radios for wheeled vehicles and for aircraft.
Larger versions mounted on roofs and radio masts are used as base station antennas for police, ambulance and other vehicle dispatchers. The whip antenna is a monopole antenna, like a vertical dipole has an omnidirectional radiation pattern, radiating equal radio power in all azimuthal directions, with the radiated power falling off with elevation angle to zero on the antenna's axis. Whip antennas 1/4 wavelength long or less have a single main lobe, with field strength maximum in horizontal directions, falling monotonically to zero on the axis. Antennas longer than a quarter wavelength have patterns consisting of several conical "lobes". Vertical whip antennas are used for nondirectional radio communication on the surface of the Earth, where the direction to the transmitter is unknown or changing, for example in portable FM radio receivers, walkie-talkies, two-way radios in vehicles; this is because they transmit well in all horizontal directions, while radiating little radio energy up into the sky where it is wasted.
Whip antennas are designed as resonant antennas. Therefore, the length of the antenna rod is determined by the wavelength of the radio waves used; the most common length is one-quarter of the wavelength, called a "quarter-wave whip". For example, the common quarter-wave whip antennas used on FM radios in the USA are 75 cm long, one-quarter the length of radio waves in the FM radio band, which are 2.78 to 3.41 meters long. Half-wave antennas are common. A quarter wave vertical antenna working against a perfect infinite ground will have a gain of 5.19 dBi and about 36.8 ohms of radiation resistance. Whips mounted on vehicles use the metal skin of the vehicle as a ground plane. In hand-held devices no explicit ground plane is provided, the ground side of the antenna's feed line is just connected to the ground on the device's circuit board. Therefore, the radio itself, the user's hand, serves as a rudimentary ground plane. Since these are no larger than the size of the antenna itself, the combination of whip and radio functions more as an asymmetrical dipole antenna than as a monopole antenna.
The gain will suffer somewhat compared to a half wave metallic diople or a whip with a well defined ground plane. With stationary whips mounted on structures, an artificial "ground plane" consisting of three or four rods a quarter-wavelength long extending horizontally from the base of the whip is used; this provides a stable input impedance and pattern by helping prevent RF currents in the supporting mast and along the outside of the feed line. This type of antenna is called a ground plane antenna; the ground plane rods are sloped downward toward the ground, which lowers the main lobe of the radiation pattern and increases the normal 36.8 ohm radiation resistance closer to 50 ohms to provide a better impedance match with standard 50 ohm coaxial cable feedline. To reduce the length of a whip antenna to make it less cumbersome, an inductor is added in series with it; this allows the antenna to be made much shorter than the normal length of a quarter-wavelength, still be resonant, by cancelling out the capacitive reactance of the short antenna.
The coil is added at the base of the whip or in the middle. In the most used form, the rubber ducky antenna, the loading coil is integrated with the antenna itself by making the whip out of a narrow helix of springy wire; the helix distributes the inductance along the antenna's length, improving the radiation pattern, makes it more flexible. Another alternative used to shorten the antenna is to add a "capacity hat", a metal screen or radiating wires, at the end; however all these electrically short whips have lower gain than a full length quarter-wave whip. Multi-band operation is possible with coils at about one-half or one-third and two-thirds that do not affect the aerial much at the lowest band, but it creates the effect of stacked dipoles at a higher band. At higher frequencies (2.4 GHz, but military whips for 50 MHz to 80 MHz band exist
Antenna farm or satellite dish farm or just dish farm are terms used to describe an area dedicated to television or radio telecommunications transmitting or receiving antenna equipment, such as C, Ku or Ka band satellite dish antennas, UHF/VHF/AM/FM transmitter towers or mobile cell towers. The history of the term "antenna farm" is uncertain. In telecom circles, any area with more than three antennas could be referred to as an antenna farm. In the case of an AM broadcasting station, the multiple mast radiators may all be part of an antenna system for a single station, while for VHF and UHF the site may be under joint management. Alternatively, a single tower with many separate antennas is called a "candelabra tower". Commercial antenna farms are managed by radio stations, television stations, satellite teleports or military organizations and are very secure facilities with access limited to broadcast engineers, RF engineers or maintenance technicians; this is not only for the physical security of the location, but for safety, as there may be a radiation hazard unless stations are powered-down.
Where terrain and road access allows, mountaintop sites are attractive for non-AM broadcast stations and others, because it increases the stations' height above average terrain, allowing them to reach further by avoiding obstructions on the ground, by increasing the radio horizon. With a clearer line of sight in both cases, more signal can be received. While the same is true of a tall tower, like Paris’ Eiffel tower, such towers are expensive and difficult to access the top of, may collect and drop large amounts of ice in winter, or collapse in a severe ice storm and/or high winds. Multiple small towers allow stations to have backup facilities co-located on each other's towers for redundancy. Satellite antenna farms are located at remote locations, far away from urban development high rise buildings or airplane flight paths, to avoid and minimize disruption to transmission and reception, so as to not be an eyesore. Although most radio and TV stations are in fierce competition with each other in their broadcast markets, they will locate their broadcasting antennas near each other, in some cases, will share land or towers with each other, in the interests of space, land availability, the cost of putting a transmission building on top of a mountain.
Most metropolitan areas have at least one antenna farm, such as Mount Wilson in greater Los Angeles, Sweat Mountain in metro Atlanta, Farnsworth Peak for the Salt Lake Valley, Riverview in Tampa, Baltimore's Television Hill and Slide Mountain in the Reno/Tahoe area. Some cities instead have combined many stations onto one tower through diplexers into just one or two antennas, such as atop the Empire State Building in New York, the landmark Sutro Tower of San Francisco, or the huge Miami Gardens tower serving the Miami and Fort Lauderdale region. Cleveland, Ohio has its antenna farm in the suburb of Ohio due to Parma's high elevation. In central Oklahoma City most of the city's media outlets transmitter and tower facilities are located between the Kilpatrick Turnpike to the south and Interstate 44 to the north, Broadway Extension to the west and Interstate 35 to the east with Britton Road being the central thoroughfare. In addition, all three network affiliates and one of the 3 major radio groups have their studio facilities located within the Oklahoma City tower farm.
In the Appalachian Mountains of the Eastern United States, Poor Mountain serves most of the FM and TV stations in the Roanoke/Lynchburg market. Holston Mountain in upper East Tennessee is home to most of the FM and TV stations in the Tri-Cities DMA. Other examples are Signal Mountain near Chattanooga, Sharp's Ridge in Knoxville and Paris Mountain in Greenville, South Carolina. Other examples of co-located towers on mountain peaks in the United States are on Red Mountain in Birmingham, Alabama; the most famous broadcast antenna farm of all is the World Trade Center Tower One, on which many of the New York City television and several FM stations had their antennas. All were lost when Twin Towers One and Two collapsed after the September 11 attacks in 2001. Most of those stations reverted to broadcasting from their previous home, 200 feet lower, on the Empire State Building. Antenna farms have been the source of complaints from local neighborhoods when a new tower is added; this has been so for TV stations, which have been pursuing with alacrity the construction of new digital television antennas.
Because many of these towers are full, or were built well before there was the expectation of DTV, many stations have been forced to go through the greater expense of constructing a new tower. One such situation was in the late 1990s and early to mid-2000s. Many of the Denver metropolitan area TV stations transmitted analog TV from Lookout Mountain, but needed the extra space for more antennas. Additionally, since many people live on Lookout Mountain, there was the concern about safety, not only from falling ice or the slight risk of a tower collapse, but ongoing from the additional RF that it would create. Residents and the city of Gol
In antenna engineering, side lobes or sidelobes are the lobes of the far field radiation pattern of an antenna or other radiation source, that are not the main lobe. The radiation pattern of most antennas shows a pattern of "lobes" at various angles, directions where the radiated signal strength reaches a maximum, separated by "nulls", angles at which the radiated signal strength falls to zero. In a directional antenna in which the objective is to emit the radio waves in one direction, the lobe in that direction is designed to have a larger field strength than the others; the other lobes are called "side lobes", represent unwanted radiation in undesired directions. A side lobe in the opposite direction from the main lobe is called the back lobe; the larger the antenna is compared to the radio wavelength, the more lobes its radiation pattern has. In transmitting antennas, excessive side lobe radiation wastes energy and may cause interference to other equipment. Classified information may be picked up by unintended receivers.
In receiving antennas, side lobes may pick up interfering signals, increase the noise level in the receiver. The power density in the side lobes is much less than that in the main beam, it is desirable to minimize the sidelobe level, measured in decibels relative to the peak of the main beam. The main lobe and side lobes occur for both conditions of transmit, for receive; the concepts of main and side lobes, radiation pattern, aperture shapes, aperture weighting, apply to optics and in acoustics fields such as loudspeaker and sonar design, as well as antenna design. For a rectangular aperture antenna having a uniform amplitude distribution, the first sidelobe is -13.26 dB relative to the peak of the main beam. For such antennas the radiation pattern has a canonical form of Radiation Pattern ∝ 20 log 10 Simple substitutions of various values of X into the canonical equation yield the following results: For a circular aperture antenna having a uniform amplitude distribution, the first sidelobe level is -17.57 dB relative to the peak of the main beam.
In this case, the radiation pattern has a canonical form of Radiation Pattern ∝ 10 log 10 where J 1 is the Bessel function of the first kind of order 1. Simple substitutions of various values of X into the canonical equation yield the following results: A uniform aperture distribution, as provided in the two examples above, gives the maximum possible directivity for a given aperture size, but it produces the maximum side lobe level. Side lobe levels can be reduced by tapering the edges of the aperture distribution at the expense of reduced directivity; the nulls between sidelobes occur when the radiation patterns passes through the origin in the complex plane. Hence, adjacent sidelobes are 180° out of phase to each other; because an antenna's far field radiation pattern is a Fourier Transform of its aperture distribution, most antennas will have sidelobes, unless the aperture distribution is a Gaussian, or if the antenna is so small, as to have no sidelobes in the visible space. Larger antennas have narrower main beams, as well as narrower sidelobes.
Hence, larger antennas have more sidelobes in the visible space. For discrete aperture antennas in which the element spacing is greater than a half wavelength, the spatial aliasing effect causes some sidelobes to become larger in amplitude, approaching the level of the main lobe. Grating lobes are a special case of a sidelobe. In such a case, the sidelobes should be considered all the lobes lying between the main lobe and the first grating lobe, or between grating lobes, it is conceptually useful to distinguish between sidelobes and grating lobes because grating lobes have larger amplitudes than most, if not all, of the other side lobes. The mathematics of grating lobes is the same as of X-ray diffraction. Sidelobes and Beamwidths - An Antenna Tutorial
Mobile phone radiation and health
The effect of mobile phone radiation on human health is a subject of interest and study worldwide, as a result of the enormous increase in mobile phone usage throughout the world. As of 2015, there were 7.4 billion subscriptions worldwide, though the actual number of users is lower as many users own more than one mobile phone. Mobile phones use electromagnetic radiation in the microwave range. Other digital wireless systems, Such as data communication networks, produce similar radiation; the World Health Organization states that "A large number of studies have been performed over the last two decades to assess whether mobile phones pose a potential health risk. To date, no adverse health effects have been established as being caused by mobile phone use." In a 2018 statement, the FDA said that "the current safety limits are set to include a 50-fold safety margin from observed effects of Radio-frequency energy exposure". A cell phone is a wireless portable telephone that connects to the telephone network by radio waves exchanged with a local antenna and automated transceiver called a cellular base station.
The service area served by each provider is divided into small geographical areas called cells, all the cell phones in a cell communicate with that cell's antenna. Both the cell phone and the cell tower have radio transmitters. Since in a cellular network the same radio channels are reused every few cells, cellular networks use low power transmitters to avoid radio waves from one cell spilling over and interfering with a nearby cell using the same frequencies. Cell phones are limited to a EIRP radiated power output of 3 watts, the network continuously adjusts the phone transmitter to the lowest power consistent with good signal quality, reducing it to as low as one milliwatt when near the cell tower. Cell phone tower channel transmitters have an EIRP power output of around 50 watts; when it is not being used, unless it is turned off, a cell phone periodically emits radio signals on its control channel, to keep contact with its cell tower and for functions like handing off the phone to another tower if the user crosses into another cell.
When the user is making a call, the cell phone transmits a signal on a second channel which carries the user's voice. Existing 2G, 3G, 4G networks use frequencies in the UHF or low microwave bands, 600 MHz to 3.5 GHz. Many household wireless devices such as Wifi networks, garage door openers, baby monitors use other frequencies in this same frequency range. Radio waves decrease in intensity by the inverse square of distance as they spread out from a transmitting antenna. So the cell phone transmitter, held close to the user's face when talking, is a much greater source of human exposure than the cell tower transmitter, at least hundreds of meters away from the public on a cell tower. A user can reduce their exposure by using a headset and keeping the cell phone itself further away from their body. Next generation 5G cellular networks, which began deploying in 2019, use higher frequencies in or near the millimeter wave band, 24 to 52 GHz. Millimeter waves are absorbed by atmospheric gases so 5G networks will use smaller cells than previous cellular networks, about the size of a city block.
Instead of a cell tower, each cell will use an array of multiple small antennas mounted on existing buildings and utility poles. In general, millimeter waves penetrate less into biological tissue than microwaves, are absorbed within the first centimeter of the body surface. A 2010 review stated that "The balance of experimental evidence does not support an effect of'non-thermal' radiofrequency fields" on the permeability of the blood-brain barrier, but noted that research on low frequency effects and effects in humans was sparse. A 2012 study of low-frequency radiation on humans found "no evidence for acute effects of short-term mobile phone radiation on cerebral blood flow". There is no strong or consistent evidence that mobile phone use increases the risk of getting brain cancer or other head tumors; the United States National Cancer Institute points out that "Radiofrequency energy, unlike ionizing radiation, does not cause DNA damage that can lead to cancer. Its only observed biological effect in humans is tissue heating.
In animal studies, it has not been found to cause cancer or to enhance the cancer-causing effects of known chemical carcinogens." The majority of human studies have failed to find a link between cancer. In 2011 a World Health Organization working group classified cell phone use as "possibly carcinogenic to humans"; the CDC states that no scientific evidence definitively answers whether cell phone use causes cancer. In a 2018 statement, the FDA said that "the current safety limits are set to include a 50-fold safety margin from observed effects of radiofrequency energy exposure". An analysis of an "eagerly anticipated" study using rats and mice by the National Toxicology Program indicates that due to such issues as the inconsistent appearances of "signals for harm" within and across species and the increased chances of false positives due to the multiplicity of tests, the positive results seen are more due to random chance; the full results of the study were released in February 2018. A decline in male sperm quality has been observed over several decades.
Studies on the impact of mobile radiation on male fertility are conflicting, the effects of the radiofrequency electromagnetic radiation emitted by these devices on the reproductive systems are under active debate. A 2012 review concluded that "together, the results of these studies have shown that RF-EMR decreases sperm count and motility