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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 cable has a characteristic impedance of 75 ohms, and a capacitance of around 20pF/ft (60pF/m). [1] The 75 ohm impedance matches a dipole antenna in free space. RG (for radio guide ) was originally a unit indicator for bulk radio frequency (RF) cable in the U.S. military's Joint Electronics Type Designation System .
The connector reliably carries signals at frequencies up to 100 MHz. [1] The coupling shell has a 5 / 8 inch 24 tpi UNEF standard thread. [4] The most popular cable plug and corresponding chassis-mount socket carry the old Signal Corps labels PL-259 (plug #259) and SO-239 (socket #239). [12]
It may be said that radio interference and its correction arose with the first spark-gap experiment of Marconi in the late 1800s. [3] As radio communications developed in the first half of the 20th century, interference between broadcast radio signals began to occur and an international regulatory framework was set up to ensure interference-free communications.
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 ...
It is typically applied to enclosures, for isolating electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs (see Shielded cable). Electromagnetic shielding that blocks radio frequency (RF) electromagnetic radiation is also known as RF shielding .
An RF connector (radio frequency connector) is an electrical connector designed to work at radio frequencies in the multi-megahertz range. RF connectors are typically used with coaxial cables and are designed to maintain the shielding that the coaxial design offers.
The modulator is then programmed to broadcast the signals on a certain frequency. That RF broadcast is then received by the connected TV. When the TV is tuned to the programmed channel, the video and audio signal of the source device is accessed. RF modulation can become difficult in a CATV system. High pass, low pass, and notch filters must be ...