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Diagram of leaky feeder cable. A leaky feeder is a communications system used in underground mines and inside tunnels. [1] Manufacturers and cabling professionals use the term "radiating cable" [2] [3] [better source needed] [4] as this implies that the cable is designed to radiate: something that a typical coaxial cable is generally not intended to do.
The antennas contained in mobile phones, including smartphones, emit radiofrequency (RF) radiation (non-ionizing "radio waves" such as microwaves); the parts of the head or body nearest to the antenna can absorb this energy and convert it to heat or to synchronised molecular vibrations (the term 'heat', properly applies only to disordered molecular motion).
The FCC limits for maximum permissible workplace exposure to shortwave radio frequency energy in the range of 3–30 MHz has a plane-wave equivalent power density of (900/ f 2) mW/cm 2 where f is the frequency in MHz, and 100 mW/cm 2 from 0.3 to 3.0 MHz.
By 1900 application of high-frequency current to the body was used experimentally to treat a wide variety of medical conditions in the quack medical field of electrotherapy. In 1899 Austrian chemist von Zaynek determined the rate of heat production in tissue as a function of frequency and current density, and first proposed using high-frequency ...
This is an accepted version of this page This is the latest accepted revision, reviewed on 7 February 2025. Claimed sensitivity to electromagnetic fields This article is about a pseudomedical diagnosis. For the recognized effects of electromagnetic radiation on human health, see Electromagnetic radiation and health. Electromagnetic hypersensitivity Idiopathic environmental intolerance ...
Thus, the transmitting coil is a good EM near-field generator at radio frequency, but a poor EM radiation transmitter at radio frequency. The receiver coil picks up the oscillations at RF frequencies produced by precession of the magnetic moment of nuclei inside the subject. The signal acquired by the coil is thus an induced emf, and is not the ...
In a radio antenna, the feed line (feedline), or feeder, is the cable or other transmission line that connects the antenna with the radio transmitter or receiver.In a transmitting antenna, it feeds the radio frequency (RF) current from the transmitter to the antenna, where the energy in the current is radiated as radio waves.
Radio propagation is the behavior of radio waves as they travel, or are propagated, from one point to another in vacuum, or into various parts of the atmosphere. [1]: 26‑1 As a form of electromagnetic radiation, like light waves, radio waves are affected by the phenomena of reflection, refraction, diffraction, absorption, polarization, and scattering. [2]