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Q. Figure of merit of efficiency of a circuit or coil. Ratio of inductive reactance to resistance in
servos. Relationship between stored energy (capacitance) and rate of dissipation in certain types of
electric elements, structures, or materials.
Q-BAND. A band of frequency in the range of 36GHz to 46GHz.
QUAD ANTENNA. An antenna which consists of two square loops which are cut to a quarter wavelength.
QUADRATURE. The state of being separated in phase by 90 degrees. Pertaining to the phase
relationship between two periodic quantities varying with the same period, that is, with the same frequency
or repetition rate, when the phase difference between them is one-quarter of their period.
QUADRATURE AMPLITUDE MODULATION. Quadrature modulation in which the two carriers are
amplitude modulated. (QAM).
QUADRATURE PHASE-SHIFT KEYING. Phase-shift
keying in which four different phase angles are used. In QPSK, the four angles are usually out
of phase by 90 degrees. Synonyms quadriphase, quaternary phase-shift keying. quadrature phase-shift keying (QPSK).
QUALITY FACTOR: [Q]. The ratio of capacitive reactance to resistance.
QUALITY (OF SOUND). The factor that distinguishes tones of pitch and loudness.
QUANTIZE: The process of restricting a variable to a number of discrete values.
QUANTIZED WAVE. A wave created by the arbitrary division of the entire range of amplitude (or frequency, or phase) values of an analog wave into a series of standard values. Each sample takes the standard value nearest its actual value when modulated.
QUANTIZING NOISE. Distortion introduced by quantizing the signal.
QUANTUM-MECHANICAL TUNNELING. The action of an electron crossing a PN junction because
of tunnel effect.
QUARTER-WAVE ANTENNA. Same as the MARCONI ANTENNA.
QUARTZ. A mineral.
QUARTZ CRYSTAL. Also called a crystal. [Oscillator Manufacturers]
QUARTZ OSCILLATOR. An oscillator in which a quartz crystal is used to stabilize the frequency.
QUIESCENCE. The state of an amplifier with no signal applied. The operating conditions that
exist in a circuit when no input signal is applied to the circuit.
QUIESCENT CURRENT. The current flowing in a circuit during a period in which a circuit element is not performing an active function in the system.
QUIESCENT STATE. The period when a transistor, tube, or other circuit element is not performing an active function in the circuit.
