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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 reception or transmission of radio waves, a form of electromagnetic radiation, to or from an antenna within a Faraday cage is heavily attenuated or blocked by the cage; however, a Faraday cage has varied attenuation depending on wave form, frequency, or the distance from receiver or transmitter, and receiver or transmitter power.
Coronas can generate audible and radio-frequency noise, particularly near electric power transmission lines. Therefore, power transmission equipment is designed to minimize the formation of corona discharge. Corona discharge is generally undesirable in: Electric power transmission, where it causes: Power loss; Audible noise
Cross-section through a coaxial cable showing shielding and other layers. One example is a shielded cable, which has electromagnetic shielding in the form of a wire mesh surrounding an inner core conductor. The shielding impedes the escape of any signal from the core conductor, and also prevents signals from being added to the core conductor.
In telecommunications, the free-space path loss (FSPL) (also known as free-space loss, FSL) is the attenuation of radio energy between the feedpoints of two antennas that results from the combination of the receiving antenna's capture area plus the obstacle-free, line-of-sight (LoS) path through free space (usually air). [1]
The heyday for grid leak detectors was the 1920s, when battery operated, multiple dial tuned radio frequency receivers using low amplification factor triodes with directly heated cathodes were the contemporary technology. The Zenith Models 11, 12, and 14 are examples of these kinds of radios. [8]
TEMPEST (Telecommunications Electronics Materials Protected from Emanating Spurious Transmissions [1]) is a U.S. National Security Agency specification and a NATO certification [2] [3] referring to spying on information systems through leaking emanations, including unintentional radio or electrical signals, sounds, and vibrations.
A radio signal from the antenna-ground circuit "turns on" the coherer, enabling current flow in the battery-sounder circuit, activating the sounder, S. The coils, L, act as RF chokes to prevent the RF signal power from leaking away through the relay circuit. A radio receiver circuit using a coherer detector (C). The "tapper" (decoherer) is not ...