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88 broadside • bubble memory
broadside In a perpendicular direction; for example,
broadside radiation from an antenna.
broadside antenna See BROADSIDE ARRAY.
broadside array Also called broadside antenna. A
phased group of antennas arranged so maximum
radiation occurs in directions perpendicular to
the plane containing the driven elements. This requires
that all of the antennas be fed in phase.
The elements can be half-wave dipoles or fullwave,
center-fed conductors. Full-wave elements
have a slight gain over half-wave elements. At
high frequencies, this type of array is usually
constructed from two driven antennas. At veryhigh
and ultra-high frequencies there can be several
driven antennas. The antennas can each
consist of a single element, or they can be Yagis,
loops, or other systems with individual directive
properties. In general, the larger the number of
elements in the entire array, the greater the gain
and directivity.
Phasing
lines
To
TX
broadside array
In-phase
dipoles
Maximum
radiation
broad tuning Tuning that is characterized by
pronounced signal width, often resulting in
adjacent-channel interference. A common cause
of such impaired selectivity is low Q in the tuned
circuit(s).
Broca galvanometer A device consisting of an
astatic magnetic arrangement, with a coil enclosing
central consequent poles. The device is characterized
by fast response and high sensitivity.
bromine Symbol, Br. A nonmetallic element of the
halogen family. Atomic number, 35. Atomic
weight, 79.90.
bronze An alloy of copper and tin that has various
uses in electronics. Also see PHOSPHOR BRONZE.
Brown and Sharpe gauge See AMERICAN WIRE
GAUGE.
Brownian movement (Robert Brown, 1773 –1858).
Random movement of microscopic particles—
especially in solutions. It occurs because of colli-
sions of molecules with the particles. Einstein
showed, in his early work, a connection between
this movement and the Boltzmann constant.
brownout A deliberate lowering of line voltage by a
power company to reduce load demands. Minor
events of this type often pass unnoticed by the
average consumer. More pronounced events produce
observable effects, such as shrinkage of
television and cathode-ray-tube (CRT) computerdisplay
images.
Bruce antenna A vertical collinear array that consists
of several resonant sections connected by
short, rigid, parallel-conductor stubs. The currents
in the radiating sections are in phase. Maximum
radiation and response occur broadside to
the antenna (omnidirectional in the horizontal
plane). Polarization is vertical. The antenna
produces gain at low radiation and response
angles, and is commonly used in repeater installations
and fixed communications stations at
very-high frequencies (VHF) and ultra-high frequencies
(UHF).
brush A usually metal or carbon strip, blade, or
block, that slides in contact with another part, as
in a motor commutator.
brush discharge Also called Saint Elmo’s fire. A
cloud of repelled ions around the tip of a pointed
conductor charged to a high voltage. It often produces
a visible glow in the air.
brush holder The housing for a brush in a motor,
generator, rheostat, slip-ring junction in a rotating
data-transmission system, etc.
brute force 1. The transmission of a signal of excessive
or unnecessary power. 2. An inefficient
approach to a problem, which might solve the
problem, but requires far more energy, effort, or
computer memory/storage space than the minimum
needed to accomplish the same result.
brute-force filter A pi-type lowpass dc power
supply filter, so called because of the extremely
large inductances and capacitances that are
generally used.
brute supply An unregulated power supply.
B-scope A cathode-ray tube (CRT), used in radar,
that presents a B DISPLAY.
B service A teletype communication system operated
by the Federal Aviation Administration
(FAA).
B-supply The dc power supply that provides anode
operating voltages, such as plate and screen voltages
in a vacuum-tube radio-frequency (RF)
power amplifier.
BT-cut crystal A piezoelectric plate cut from a
quartz crystal at an angle of rotation (relative to
the x-axis) of -49°. It has a zero temperature coefficient
of frequency at approximately 25°C. Also
see CRYSTAL AXES and CRYSTAL CUTS.
Btu Abbreviation of BRITISH THERMAL UNIT.
BuAer Abbreviation of Bureau of Aeronautics.
bubble memory In digital-computer practice, a
special type of static magnetic memory. The mag-