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MASTER OSCILLATOR—In a transmitter, the oscillator that establishes the carrier frequency of the
output [18].
MASTER OSCILLATOR POWER AMPLIFIER (MOPA)—A transmitter in which the oscillator is
isolated from the antenna by a power amplifier [12].
MATRIX—In computers, a logic network in the form of an array of input leads and output leads with logic
elements connected at some of their intersections [13].
MATTER—Any physical entity that possesses mass [1].
MAXIMUM USABLE FREQUENCY—Maximum frequency that can be used for communications
between two locations for a given time of day and a given angle of incidence [10].
MEASURE (METROLOGY AUTOMATED SYSTEM FOR UNIFORM RECALL AND
REPORTING)—The Navy data processing system designed to provide a standardized system for the
recall, scheduling, and documenting of test equipment into calibration facilities [16].
MECHANICAL-ROTATION FREQUENCY—The speed in revolutions per minute of armatures in
electric motors and engine-driven generators; blade speed in turbines [16].
MECHANICAL SCANNING—The reflector, its feed source, or the entire antenna is moved in a desired
pattern [18].
MECHANIZATION—Using electric or electro-mechanical switches to represent logic circuits (AND, OR,
NOT, NOR, NAND) [13].
MEDIUM—The vehicle through which a wave travels from one point to the next. Air, water, and wood are
examples [10].
MEDIUM ALTITUDE ORBIT—An orbit from 2,000 to 12,000 miles above the earth. The rotation rate of
the earth and satellite are quite different, and the satellite moves quickly across the sky [17].
MEDIUM FREQUENCY—The band of frequencies from 300 kHz to 3 MHz [17].
MEGA—A prefix meaning one million; also MEG [1].
MEGGER—Common name for a megohmmeter [3] [16].
MEGOHMMETER—A meter that measures very large values of resistance; usually used to check for
insulation breakdown in wires [3].
METALLIC ARMOR—A protective covering for wires or cables. Made as a woven wire braid, metal
tape, or interlocking metal cover. Made from steel, copper, bronze, or aluminum [4].
METALLIC, INSULATOR—A shorted quarter-wave section of transmission line [11].
METALLIC RECTIFIER—Also known as a DRY-DISC RECTIFIER. A metal-to-semiconductor, large-
area, contact device in which a semiconductor is sandwiched between two metal plates. This
asymmetrical construction permits current to flow more readily in one direction than the other [7].
METAL-OXIDE SEMICONDUCTOR FIELD-EFFECT TRANSISTOR—See MOSFET [7].
METER—A device used to measure a specific quantity, such as current, voltage, or frequency [3].
