1-7 BEL—The unit that expresses the logarithmic ratio between the input and output of any given component, circuit, or system [16]. BETA—The ratio of a change in collector current to a corresponding change in base current when the collector voltage is constant in a common-emitter circuit [7]. BEVERAGE ANTENNA—A horizontal, long-wire antenna designed for reception and transmission of low-frequency, vertically polarized ground waves [10]. BIAS—Difference of potential applied to a vacuum tube or transistor to establish a reference operating level [13]. BIAS CURRENT—Current that flows through the base-emitter junction of a transistor and is adjusted to set the operating point of the transistor [13]. BIDIRECTIONAL ARRAY—An array that radiates in opposite directions along the line of maximum radiation [10]. BINARY—(1) A number system that uses a base, or radix, of 2. Two digits (1 and 0) are used in the binary system. (2) Pertaining to a characteristic that involves the selection, choice, or condition in which there are only two possibilities. (3) A bistable multivibrator (flip-flop) is one example of a binary device [13]. BINARY CODE—A method of representing two possible conditions (onor off, high or low, one or zero, the presence of a signal or absence of a signal). Electronic circuits designed to work in such a way that only two conditions are possible [13]. BINARY-CODED—The state in which conditions are expressed by a series of binary digits (0's and 1's) [13]. BINARY DIGIT—(1) A character that represents one of the two digits in the number system that has a radix of two. (2) Either of the digits 0 or 1 that may be used to represent the binary conditions of on or off[13]. BINARY NOTATION—See BINARY NUMBER SYSTEM [13]. BINARY NUMBER SYSTEM—A number system using two digits, symbols, or characters (usually 1 and 0) [13]. BINARY POINT—The radix point that separates powers of two and fractional powers of two in a binary number [13]. BISTABLE—A device that is capable of assuming either one of two stable states [13]. BISTABLE MULTIVIBRATOR—A multivibrator that has two stable states. It remains in one of the states until a trigger is applied. It then flips to the other stable state and remains there until another trigger is applied. Also referred to as a FLIP-FLOP [9] [13]. BLACK—The reference color of equipment that passes unclassified information. It normally refers to patch panels [17]. BLEEDER CURRENT—The current through a bleeder resistor. In a voltage divider, bleeder current is usually determined by the 10 percent rule of thumb [1]. BLEEDER RESISTOR—A resistor used to draw a fixed current [1].