In United States regulatory law, an unintentional radiator is any device that is designed to use

radio frequency Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around . This is roughly between the u ...

electrical signals within itself, or sends radio frequency signals over conducting cabling to other equipment, but is not intended to radiate radio frequency energy. An incidental radiator is a device that can generate radio frequency electrical energy even though it is not intentionally designed to do so.United States Code 47, §15.3(n) - Definitions
/ref> Unintentional and incidental radio frequency radiation can interfere with other electronic devices. In the United States, limits on radiated emissions from unintentional and incidental radiators are established by the Federal Communications Commission. Similar regulations have been promulgated by other governments. Reference is usually made in regulations to technical standards established by organizations such as ANSI, IEC and ITU.

Example unintentional and incidental radiating devices

computer A computer is a machine that can be Computer programming, programmed to automatically Execution (computing), carry out sequences of arithmetic or logical operations (''computation''). Modern digital electronic computers can perform generic set ...

is a typical example of an unintentional radiator. Radio frequency signals used within the computer circuitry may be unintentionally coupled to the power cord or to an interconnecting cable, which then acts as an antenna. A

radio receiver In radio communications, a radio receiver, also known as a receiver, a wireless, or simply a radio, is an electronic device that receives radio waves and converts the information carried by them to a usable form. It is used with an antenna. ...

will often use an

intermediate frequency In communications and electronic engineering, an intermediate frequency (IF) is a frequency to which a carrier wave is shifted as an intermediate step in Transmission (telecommunications), transmission or reception. The intermediate frequency is ...

which is detectable outside the radio—the concept behind at least one

audience measurement Audience measurement calculates how many people are in an audience, usually in relation to radio listenership and television viewership, but also in relation to newspaper and magazine readership and, increasingly, web traffic. The term is someti ...

concept for roadside detection of

radio station Radio broadcasting is the broadcasting of audio (sound), sometimes with related metadata, by radio waves to radio receivers belonging to a public audience. In terrestrial radio broadcasting the radio waves are broadcast by a land-based rad ...

s which passing

motorist Driving is the controlled operation and movement of a land vehicle, including cars, motorcycles, trucks, and buses. A driver's permission to drive on public highways is granted based on a set of conditions being met, and drivers are required to ...

s are listening to. Examples of incidental radiators include

electric motors An electric motor is a machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate Laplace force i ...

transformers ''Transformers'' is a media franchise produced by American toy company Hasbro and Japanese toy company Tomy, Takara Tomy. It primarily follows the heroic Autobots and the villainous Decepticons, two Extraterrestrials in fiction, alien robot fac ...

dimmers A dimmer is a device connected to a light fixture and used to lower the brightness of the Lighting, light. By changing the voltage waveform applied to the lamp, it is possible to lower the Luminous intensity, intensity of the light output. Al ...

, and

corona Corona (from the Latin for 'crown') most commonly refers to: * Stellar corona, the outer atmosphere of the Sun or another star * Corona (beer), a Mexican beer * Corona, informal term for the coronavirus or disease responsible for the COVID-19 ...

from electrical powerlines. Radiated emissions from these commonly create

interference Interference is the act of interfering, invading, or poaching. Interference may also refer to: Communications * Interference (communication), anything which alters, modifies, or disrupts a message * Adjacent-channel interference, caused by extra ...

on AM radio receivers and on

television Television (TV) is a telecommunication medium for transmitting moving images and sound. Additionally, the term can refer to a physical television set rather than the medium of transmission. Television is a mass medium for advertising, ...

receivers.

Regulatory overview

In North America, active devices that are characterized as unintentional radiators are governed by

Part 15 Code of Federal Regulations, 'Title 47, Part 15(47 CFR 15) is an oft-quoted part of Federal Communications Commission (FCC) rules and regulations regarding unlicensed transmissions. It is a part of Title 47 of the Code of Federal Regulatio ...

of the

FCC The Federal Communications Commission (FCC) is an independent agency of the United States government that regulates communications by radio, television, wire, internet, wi-fi, satellite, and cable across the United States. The FCC maintains ju ...

regulations. In Canada, Innovation, Science and Economic Development considers them as interference-causin
Equipment
Globally, most domestic regulation of unintentional radiators are based on

ITU The International Telecommunication Union (ITU)In the other common languages of the ITU: * * is a specialized agency of the United Nations responsible for many matters related to information and communication technologies. It was established ...

recommendations. Generally, this means the device leaks a signal at some level. Microprocessor-controlled appliances, anything with a

clock signal In electronics and especially synchronous digital circuits, a clock signal (historically also known as ''logic beat'') is an electronic logic signal (voltage or current) which oscillates between a high and a low state at a constant frequency and ...

, and switching voltage regulators all make some kind of noise, at the repetition frequency and at harmonics. In most countries, government agencies regulate how much leakage is tolerated. This prevents leakage from

cable television Cable television is a system of delivering television programming to consumers via radio frequency (RF) signals transmitted through coaxial cables, or in more recent systems, light pulses through fibre-optic cables. This contrasts with bro ...

systems, for example, from interfering with radio communications between aircraft and

control tower Air traffic control (ATC) is a service provided by ground-based air traffic controllers who direct aircraft on the ground and through a given section of controlled airspace, and can provide advisory services to aircraft in non-controlled a ...

s. Because it costs money to filter out noise, there is always a balance struck between regulatory compliance and perfect filtering in these devices.

Microwave oven A microwave oven, or simply microwave, is an electric oven that heats and cooks food by exposing it to electromagnetic radiation in the microwave frequency range. This induces Dipole#Molecular dipoles, polar molecules in the food to rotate and ...

s or devices with microprocessors may leak within allowable limits but may generate an undesired signal that interferes with a licensed communications device. It also generally means that users who intentionally radiate signals ( TV stations and

cell phone A mobile phone or cell phone is a portable telephone that allows users to make and receive calls over a radio frequency link while moving within a designated telephone service area, unlike fixed-location phones ( landline phones). This radio ...

companies) can order the device turned off if it interferes with their licensed operations. There is an entire industry based on

regulatory compliance In general, compliance means conforming to a rule, such as a specification, policy, standard or law. Compliance has traditionally been explained by reference to deterrence theory, according to which punishing a behavior will decrease the viol ...

: manufacturers shipping a product to a foreign country must comply with each country's limitations on leakage of interfering signals. For example, in Germany the

TÜV TÜVs (; short for , ) are internationally active, independent service companies from Germany and Austria that test, inspect and certify technical systems, facilities and objects of all kinds in order to minimize hazards and prevent damages. T ...

issues regulatory rules for unintentional radiators. The big cylindrical bumps on the cable to monitors and laptop chargers are

ferrite cores Ferrite may refer to: * Ferrite (iron), one of the allotropes of iron that is stable at room temperature and pressure, α-Fe * Ferrite (magnet), a ferromagnetic ceramic material See also * * Ferrite bead, a component placed on the end of a data c ...

which reduce undesired signals.

References

{{reflisthttps://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/h_sf06127.html Radio electronics Electromagnetic compatibility