18WuD2x

U 1. Symbol for URANIUM. 2. Abbreviation of
UNIT.
u Symbol (ital.) for UNIFIED ATOMIC MASS UNIT.
Ua Abbreviation of unit of activity (electroencephalography).
UAM Abbreviation of underwater-to-air missile.
ubiquitous carrier A current carrier (especially an
electron) whose velocity is so high, or mechanism
of transfer so subtle, that it appears to be in two
places simultaneously. Thus, in the tunnel diode,
during the interval of tunneling a single electron,
appears to be on both sides of the barrier at the
same time.
Ubitron A tube in which a periodic magnetic field
causes an electron beam to undulate. Through its
transverse velocity component, the beam interacts
with a radio-frequency wave, and its kinetic
energy is converted into radio-frequency energy.
The ubitron can be used as an amplifier or oscillator.
UCT Abbreviation of UNIVERSAL COORDINATED
TIME.
UDC Abbreviation of universal decimal classification.
UDOP Abbreviation of ultra-high-frequency Doppler.
A 440-MHz phase-coherent tracking system
used to determine the velocity and position of
missiles and space vehicles.
UEP Abbreviation of underwater electric potential.
UFET Abbreviation of unipolar field-effect transistor.
(Also, UNIFET.) See UNIPOLAR TRANSISTOR.
UFO See UNIDENTIFIED FLYING OBJECT.
UG Abbreviation of underground.
UHF Abbreviation of ULTRAHIGH FREQUENCY.
UHF adaptor See UHF CONVERTER, 1.
UHF capacitor A button-type capacitor. Because
of its unique design, it is an efficient bypass capacitor
at ultrahigh frequencies.
UHF converter 1. A circuit, usually consisting of a
radio-frequency amplifier and mixer, for converting
ultra-high-frequency (UHF) signals to a lower
band of frequencies. 2. A circuit for converting
UHF television signals to very-high-frequency
(VHF) signals so that they can be accommodated
by an older (VHF only) television receiver. See
UHF TELEVISION CHANNELS and VHF TELEVI-
SION CHANNELS.
UHF
in
UHF
amp.
Mixer
Osc.
HF
amp.
UHF converter, 1
HF
out
UHF diode A semiconductor diode whose rectification
efficiency is good at ultra-high frequencies.
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