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Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency [1] range from around 20 kHz to around 300 GHz.
The three lightest known isotopes have half-lives of under 50 μs, with the lightest reported isotope 252 Rf having a half-life shorter than one microsecond. [ 63 ] [ 64 ] The isotopes 256 Rf, 258 Rf, 260 Rf are more stable at around 10 ms; 255 Rf, 257 Rf, 259 Rf, and 262 Rf live between 1 and 5 seconds; and 261 Rf, 265 Rf, and 263 Rf are more ...
In this example there are 1000 pulses per second (one kilohertz pulse rate) with a gated pulse width of 42 μs. The pulse packet frequency in this example is 27.125 MHz of RF energy. The duty cycle for a pulsed radio frequency is the percent time the RF packet is on, 4.2% for this example ([0.042 ms × 1000 pulses divided by 1000 ms/s] × 100).
Radio-frequency (RF) engineering is a subset of electrical engineering involving the application of transmission line, waveguide, antenna, radar, and electromagnetic field principles to the design and application of devices that produce or use signals within the radio band, the frequency range of about 20 kHz up to 300 GHz. [1] [2] [3]
Rutherfordium (104 Rf) is a synthetic element and thus has no stable isotopes. A standard atomic weight cannot be given. The first isotope to be synthesized was either 259 Rf in 1966 or 257 Rf in 1969. There are 17 known radioisotopes from 252 Rf to 270 Rf (three of which, 266 Rf, 268 Rf, and 270 Rf, are unconfirmed) and several isomers.
The ISM bands were initially reserved for non-communications uses of RF energy, such as microwave ovens, radio-frequency heating, and similar purposes. However, in recent years the largest use of these bands has been by short-range low-power communications systems, since users do not have to hold a radio operator's license.
An RF chain is a cascade of electronic components and sub-units which may include amplifiers, filters, mixers, attenuators and detectors. [1] It can take many forms, for example, as a wide-band receiver-detector for electronic warfare (EW) applications, as a tunable narrow-band receiver for communications purposes, as a repeater in signal distribution systems, or as an amplifier and up ...
Much of the current debate is about relatively low levels of exposure to radio frequency (RF) radiation from mobile phones and base stations producing "non-thermal" effects. Some experiments have suggested that there may be biological effects at non-thermal exposure levels, but the evidence for production of health hazard is contradictory and ...