radio frequency

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frequency

 [fre´kwen-se]
1. the number of occurrences of a periodic or recurrent process in a unit of time, such as the number of electrical cycles per second measured in hertz. In cardiac pacing terminology, frequency is expressed by the formula: frequency = ½ × pulse width.
2. the number of occurrences of a particular event or the number of members of a population or statistical sample falling in a particular class.
radio frequency the range of frequencies of electromagnetic radiation between 10 kilohertz and 100 gigahertz, used for radio communication.
relative frequency the ratio of the number of occurrences of a specified phenomenon in a population to the total size of the population.
urinary frequency urination at short intervals without increase in daily volume of urinary output, due to reduced bladder capacity or cystitis.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

radio frequency

An MRI term for an electromagnetic wave with a frequency in the same range as that used for transmitting radio and television signals. The RF pulses used in MRI are usually in the 1–100 megahertz range, which cause heating of a structure or tissue due to RF pulse absorption.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.
References in periodicals archive ?
Here [t.sub.1] is the neutron flight time through the coil, and the unit vector [n.sub.2] is determined by a phase [delta] of a radio-frequency field at the moment a neutron enters a coil.
Lesh says the radio-frequency technique appears safe and effective.
The emissions lasted for only a couple of minutes, but the astronomers kept the instrument on that frequency for a week while they set up a second receiver to monitor possibly misleading radio-frequency interference.
For skilled designers, researchers, and engineers as well as students, electrical engineers review recent developments in optimizing the performance of analog, mixed-signal, and radio-frequency circuits.
NIST researchers led efforts within the IEEE 802.15 Task Group on Coexistence to study, characterize, and quantify the radio-frequency interference between Bluetooth and the now widely deployed IEEE 802.11b WLAN devices.
telescope that had served for 26 years as a leading tool worldwide for studying cosmic sources of radio-frequency signals came crashing down in minutes last week.
Radio-Frequency Heating in Food Processing: Principles and Applications
Following the long established theory of synchrotron radiation emission, all synchrotron radiation is emitted in harmonics of the frequency of the accelerating radio-frequency field.
NASA has been studying debris hazards to (and caused by) spacecraft for a decade, and there is a host of international organizations involved with the dense thicket of regulations governing radio-frequency interference.

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