18WuD2x

64 baseband frequency response • BASIC
transmission, it is about 10 Hz to 20 kHz or 30
kHz; for fast-scan television, it consists of frequencies
up to several megahertz. This range is
determined by bandpass and/or lowpass filters
in the AF or composite video section of the transmitter.
base bias The steady dc voltage applied to the base
electrode of a transistor to determine the operating
point along the transistor characteristic
curve.
base-bulk resistance The resistance of the semiconductor
material in the base layer of a bipolar
transistor.
base-charging capacitance In the commonemitter
connection of a bipolar transistor, the internal
capacitance of the base-emitter junction.
base current Symbol, I B . Current flowing through
the base electrode of a bipolar transistor. Also see
AC BASE CURRENT and DC BASE CURRENT.
base electrode See BASE, 1. Also called base element.
base element 1. Base electrode. 2. One of the basic
metals, such as iron or tin, that are not generally
considered precious (as opposed to
NOBLE).
base-e logarithm See NAPIERIAN LOGARITHM.
base film The plastic substrate of a magnetic
recording tape.
base frequency 1. The frequency of the principal,
or strongest, component in a complex signal or
waveform; also called basic frequency. 2. The frequency
of operation of a base-station transmitter
when the receiver is tuned to a second channel.
base-input circuit A common-collector circuit,
common-emitter circuit, or emitter follower.
base insulator A stout dielectric insulator, used to
support a heavy conducting element and keep the
conductor isolated from other possible conductors
or conductive paths.
base line In visual alignment procedures involving
an oscilloscope and radio-frequency (RF) sweep
generator, a zero-voltage reference line developed
by the generator as a horizontal trace on the oscilloscope
screen.
baseline stabilizer A clamping circuit that holds
the reference voltage of a waveform to a predetermined
value. Also called DC RESTORER.
base-loaded antenna A usually vertical antenna or
radiating element, the electrical length of which is
adjusted by means of a loading coil or tuned circuit
in series with, and positioned at the bottom
of, the antenna or radiator.
base material In printed circuits, the dielectric
material used as a substrate for the metal pattern.
Also called base medium.
base notation The numbering or radix system
used in any application (as octal, decimal, binary,
or hexadecimal).
base number See BASE, 4.
base pin One of the straight prong-like terminals
on an electrical or electronic component; it is
base line
Base
line
used to provide support for the device and to allow
a physical connection between the socket terminal,
into which it fits, and one of the internal
electrodes of the device.
base plate The chassis plate upon which components
are mounted before wiring.
base potential See BASE VOLTAGE.
base region See BASE, 1.
base resistance Symbol, R B . Resistance associated
with the base electrode of a bipolar transistor.
Also see AC BASE RESISTANCE and DC BASE
RESISTANCE.
base resistor The external resistor connected to
the base of a bipolar transistor. In the commonemitter
circuit, the base resistor is analogous to
the gate resistor of a field-effect transistor (FET)
circuit.
base spreading resistance Symbol, r BB . In a bipolar
transistor, the bulk-material resistance of
the base region between the collector junction
and emitter junction.
base station The head station or fixed home station
in a communication network.
base-10 logarithm Abbreviation, log 10 . A logarithm
based on the decimal number 10. If log 10 (x) = y,
then 10 y = x. Base-10 logarithms are commonly
used in engineering. Compare NAPIERIAN LOGA-
RITHM.
base voltage Symbol, V B . The voltage at the base
electrode of a bipolar transistor. Also see AC
BASE VOLTAGE and DC BASE VOLTAGE.
BASIC Acronym for BEGINNER’S ALL-PURPOSE
SYMBOLIC INSTRUCTION CODE, a relatively
primitive, but versatile and easy-to-learn computer
language developed at Dartmouth College.