Search results
Results from the WOW.Com Content Network
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.
Tunnel transmitters are used in Germany only for audio transmitters working in FM-range and for further radio services, such as mobile phone services which also work in this frequency range. [ citation needed ] Elsewhere, there are also tunnel transmitters for audio broadcast transmitters, which work in the long and medium wave bands.
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.
This high-frequency, high-voltage signal creates electromagnetic radiation that has, according to Van Eck, "a remarkable resemblance to a broadcast TV signal". [3] The signal leaks out from displays and may be captured by an antenna, and once synchronization pulses are recreated and mixed in, an ordinary analog television receiver can display ...
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.
Skin depth, δ, is defined as the depth where the current density is just 1/e (about 37%) of the value at the surface; it depends on the frequency of the current and the electrical and magnetic properties of the conductor. Induction cookers use stranded coils to reduce heating of the coil itself due to skin effect. The AC frequencies used in ...
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]