Editing Unintentional radiator

In United States regulatory law, an '''unintentional radiator''' is any device that is designed to use [[radio frequency]] electrical signals within itself, or sends radio frequency signals over conducting cabling to other equipment, but is not intended to radiate radio frequency energy.<ref>[https://www.law.cornell.edu/cfr/text/47/15.3 United States Code 47, §15.3(z) - Definitions]</ref> An '''incidental radiator''' is a device that can generate radio frequency electrical energy even though it is not intentionally designed to do so.<ref>[https://www.law.cornell.edu/cfr/text/47/15.3 United States Code 47, §15.3(n) - Definitions]</ref> Unintentional and incidental radio frequency radiation can [[Electromagnetic_interference|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==
A [[computer]] 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 [[receiver (radio)|radio receiver]] will often use an [[intermediate frequency]] which is detectable outside the radio&mdash;the concept behind at least one [[audience measurement]] concept for roadside detection of [[radio station]]s which passing [[motorist]]s are listening to.

Examples of incidental radiators include [[electric motor|electric motors]], [[transformer|transformers]], [[dimmer|dimmers]], and [[corona discharge|corona]] from [[electric power transmission|electrical powerlines]].  Radiated emissions from these commonly create [[Interference (communication)|interference]] on [[AM radio|AM radio receivers]] and on [[television]] receivers.

==Regulatory overview==
In North America, active devices that are characterized as unintentional radiators are governed by [[Title 47 CFR Part 15|Part 15]] of the [[Federal Communications Commission|FCC]] regulations. In Canada, [[Innovation, Science and Economic Development Canada|Innovation, Science and Economic Development]] considers them as interference-causing [https://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/h_sf06127.html Equipment]. Globally, most domestic regulation of unintentional radiators are based on [[ITU]] recommendations.

Generally, this means the device leaks a signal at some level. Microprocessor-controlled appliances, anything with a [[clock signal]], and [[switching voltage regulator]]s 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]] systems, for example, from interfering with radio communications between aircraft and [[control tower]]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]]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 ([[Television|TV stations]] and [[Cellular telephone|cell phone]] companies) can order the device turned off if it interferes with their licensed operations.

[[Image:Cable end.JPG|thumb|right|Ferrite bead at the end of a [[USB]] cable]]
There is an entire industry based on [[Compliance (regulation)|regulatory compliance]]: 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 [[Technischer Überwachungsverein|TÜV]] issues regulatory rules for unintentional radiators. The big cylindrical bumps on the cable to monitors and laptop chargers are [[ferrite bead|ferrite cores]] which reduce undesired signals.

==See also==
* [[Intentional radiator]]
* [[Product certification]]

==References==
{{reflist}}https://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/h_sf06127.html
[[Category:Radio electronics]]
[[Category:Electromagnetic compatibility]]