18WuD2x

204 distributed component • diversity gain
nents are often unintended, but they can be useful.
Compare DISCRETE COMPONENT and
LUMPED COMPONENT.
distributed constant See DISTRIBUTED COMPO-
NENT.
distributed-constant delay line A delay line
whose capacitance and inductance are distributed
throughout the line. Compare LUMPED-
CONSTANT DELAY LINE.
distributed inductance Symbol, L d . Inductance
that is dispersed throughout a system or component,
rather than being lumped in one place,
such as in a coil (e.g., the inductance of an antenna
or capacitor).
distributed network 1. A network in which electrical
properties (such as resistance, inductance,
and capacitance) are distributed over a measurable
interval, area, or volume. 2. A network
whose characteristics do not depend on frequency
within a given range.
distributed-parameter network A network composed
of distributed components, rather than
lumped components.
distributed pole In a motor or generator, a pole
having a DISTRIBUTED WINDING.
distributed resistance Symbol, R d . Resistance
that is dispersed throughout a component or circuit,
rather than being lumped in one place, such
as in a resistor. An example is the high-frequency
resistance of an antenna system.
distributed-shell transformer A transformer having
two complete closed cores that are perpendicular
to each other.
distributed winding In a motor or generator, a
winding that is placed in several slots (rather
than in one slot) under a pole piece.
distributing amplifier An amplifier having a single
input and two or more outputs that are isolated
from each other; it distributes signals to various
points.
distributing cable 1. In cable television, the cable
connecting the receiver to the transmission cable.
2. In power service, the cable running between a
feeder and a consumer’s house.
distribution 1. The selective delivery of a quantity
(e.g., power distribution). 2. In statistical analysis,
the number of times particular values of a
variable appear. Also called frequency distribution.
distribution amplifier A low-output-impedance
power amplifier that distributes a radio, television,
or audio signal to a number of receivers or
speakers.
distribution cable See DISTRIBUTING CABLE.
distribution center 1. The central point from
which a signal is routed to various points of use.
2. In electric power operations, the point at which
generation, conversion, and control equipment is
operated to route power to points of use.
distribution factor For a polyphase alternator, the
factor by which the total voltage V T can be determined
in terms of the coil voltage V C and the
number of coils n: V T = nV C . Distribution factor
k d = (sin(sd/2))/(s × sin(d/2)), where s is the
number of slots per phase per pole, and d is the
angle between adjacent slots.
distribution function In statistical analysis, the
function F(x) expressing the probability that F
takes on a value equal to or less than x.
distribution switchboard 1. A switchboard
through which signals can be routed to or among
various points. 2. A switchboard for routing electric
power to points of use.
distribution transformer A step-down transformer
used to supply low-voltage alternatingcurrent
(ac) utility power to one or more
consumers from a high-voltage line.
distributor
1. See COMMUTATOR. 2. A switching
device consisting of a rotating blade and a number
of contacts arranged in a circle. Accomplishes
sequential switching of a voltage to a number of
points in a circuit. A common example is the distributor
in the ignition system of an automotive
engine.
disturbance An undesired variation in, or interference
with, an electrical or physical quantity.
disturbed-one output In digital computers, the
one output of a magnetic cell that has received
only a partial write pulse train because it was last
written into. Compare UNDISTURBED-ONE
OUTPUT.
disturbed-zero output In digital computers, the
zero output of a magnetic cell that has received
only a partial write pulse train since it was last
read from. Compare UNDISTURBED-ZERO OUT-
PUT.
dither
1. Vibrate; quiver. 2. The condition of vibration
or quivering (e.g., the dither of a meter
pointer). 3. To blend pixels in a digitized image to
obtain various shades and colors.
divergence
1. The tendency of a collimated beam
of energy to spread out. 2. The extent to which a
collimated beam of energy spreads out, generally
measured in seconds of arc, minutes of arc, angular
degrees, or angular radians.
divergence loss Loss of transmitted sound energy,
resulting from spreading.
diverging lens A lens having a virtual focus for
parallel rays; generally a concave lens.
diversity 1. The property of consisting of two or
more independent components or media. 2. See
DIVERSITY RECEPTION. 3. See DIVERSITY
TRANSMISSION.
diversity factor 1. A measure of the degree to
which a system exhibits unity among its constituents.
2. The sum of the requirements of each
constituent of a system, divided by the total requirement
of the system.
diversity gain 1. Signal gain achieved by using
two or more receiving antennas. 2. Signal gain
achieved by using two or more transmitting antennas.