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Rf,symbol for the element rutherfordiumrutherfordium
, artificially produced radioactive chemical element; symbol Rf; at. no. 104; mass number of most stable isotope 265; m.p., b.p., and sp. gr. unknown; valence +4.
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McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
On drawings, abbr. for roof.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
RF(Radio Frequency) The range of electromagnetic frequencies above the audio range and below infrared light (from 10 kHz to 300 GHz). RF transmission includes AM and FM radio, analog and digital TV, satellite communications, cordless phones, cellular and Wi-Fi. Signals can be focused in one direction (directional), or they can transmit in all directions (omnidirectional).
Frequency and Power
The range of frequencies and power output determine how well RF signals can penetrate objects. Signals up to 5 GHz can generally transmit through wooden and plaster walls in their path, but the higher the frequency, the more an unobstructed view from transmitter to receiver is required. See line of sight, RF modulation, RF shielding, RF remote control, RFI, microwave and ISM band.
|Radio frequency ports (right) are typically coaxial cable connectors for antennas and TVs. See coaxial cable.|
|Learn Radio and TV in the 1940s|
|This ad in 1947 from National Schools touted great careers in radio and the emerging world of TV. Los Angeles-based National Schools was the first technical school in the country, originally founded in 1905 by Vrena Rosenkrantz. The first class was in auto mechanics for three students. Acquired by United Education and Software in 1985, UES closed its doors four years later.|
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