"A",
"B",
"C",
"D",
"E",
"F",
"G",
"H",
"I",
"J",
"K",
"L",
"M",
"N",
"O",
"P",
"Q",
"R",
"S",
"T",
"U",
"V",
"W",
"X",
"Y",
"Z"
UNBALANCED CRYSTAL MIXER: Circuit consisting of a section of coaxial transmission line one-half
wavelength long that is tuned to the difference (intermediate) frequency between the local
oscillator and rf echo signals.
Unbalanced Modulator: A modulator in which the modulation factor is different for the alternate half-
cycles of the carrier.
Unbalanced transmission line: A transmission line one of whose conductors is grounded.
Undesired Signal: Any signal that tends to produce degradation in the operation of equipment or systems.
Unidirectional: In one direction only.
Unidirectional Array: An array that radiates in only one general direction.
Uniform Linear Array: An antenna composed of a relatively large number of usually identical elements
arranged in a single line or in a plane with uniform spacing and usually with a uniform feed system.
Uniform-Spectrum Random Noise: White noise.
Unit Impulse: A mathematical artifice consisting of an impulse of infinite amplitude and zero width, and
having an area of unity. Note: The unit impulse is useful for the mathematical expression of the impulse
response, i.e., the transfer function, of a device. Synonym Dirac delta function.
Up-Converter: A device that translates frequencies from lower to higher frequencies.
