BANDPASS FILTERA filter that allows a narrow band of frequencies to pass through the circuit.
Rejects or attenuates frequencies that are either higher or lower than the desired band of frequencies 
BAND-REJECT FILTERA tuned circuit that does not pass a specified band of frequencies  .
BANDWIDTHThe difference between the highest usable frequency of a device (upper frequency limit)
and the lowest usable frequency of the device (lower frequency limit) - measured at the half-power
points    .
BARRETTERA type of bolometer characterized by an increase in resistance as the dissipated power
BASEThe element in a transistor that controls the flow of current carriers .
BASE(1) A reference value. (2) A number that is multiplied by itself as many times as indicated by an
exponent. (3) Same as radix. (4) The region between the emitter and collector of a transistor that
receives minority carriers injected from the emitter. It is the element that corresponds to the control grid
of an electron tube .
BASE-INJECTION MODULATORSimilar to a control-grid modulator. The gain of a transistor is
varied by changing the bias on its base .
BATTERYA device for converting chemical energy into electrical energy .
BATTERY CAPACITYThe amount of energy available from a battery. Battery capacity is expressed in
BAUDA measurement of speed based on the number of code elements or units per second .
BAYPart of an antenna array .
BEAMSee LOBE .
BEAM-LEAD CHIPSemiconductor chip with electrodes (leads) extended beyond the wafer .
BEAM-POWER TUBEAn electron tube in which the grids are aligned with the control grid. Special
beam-forming plates are used to concentrate the electron stream into a beam. Because of this action, the
beam-power tube has high power-handling capabilities .
BEARINGAn angular measurement of the direction of an object from a reference direction, such as true
BEARING RESOLUTIONAbility of a radar to distinguish between targets that are close together in
BEAT FREQUENCIESDifference and sum frequencies, which result from the combination of two
separate frequencies .
BEAT FREQUENCYThe difference between the oscillator frequency and the unknown audio frequency
BEAT-FREQUENCY OSCILLATORAn additional oscillator used in a receiver when it is receiving a
cw signal. It provides an audible tone .