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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 microwave auditory effect, also known as the microwave hearing effect or the Frey effect, consists of the human perception of sounds induced by pulsed or modulated radio frequencies. The perceived sounds are generated directly inside the human head without the need of any receiving electronic device.
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.
In 2014, researchers introduced ″AirHopper″, a bifurcated attack pattern showing the feasibility of data exfiltration from an isolated computer to a nearby mobile phone, using FM frequency signals. [5] [6] In 2015, "BitWhisper", a covert signaling channel between air-gapped computers using thermal manipulations, was introduced.
Interference with the meaning of electromagnetic interference, also radio-frequency interference (EMI or RFI) is – according to Article 1.166 of the International Telecommunication Union ' s (ITU) Radio Regulations (RR) [8] – defined as "The effect of unwanted energy due to one or a combination of emissions, radiations, or inductions upon ...
independent of frequency (λc is the cutoff wavelength). On the contrary, when the guiding structure is partly filled with dielectric, the transverse wavenumber kt is a function of frequency, so that Δθ changes as the beam is frequency scanned. On the other hand, with respect to frequency sensitivity, i.e., how quickly the beam angle scans as ...
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]
Path loss normally includes propagation losses caused by the natural expansion of the radio wave front in free space (which usually takes the shape of an ever-increasing sphere), absorption losses (sometimes called penetration losses), when the signal passes through media not transparent to electromagnetic waves, diffraction losses when part of the radiowave front is obstructed by an opaque ...