GLOSSARY

AI-1 $33(1',; , GLOSSARY ABSORPTION—(1) Absorbing light waves. Does not allow any reflection or refraction. (2) Atmospheric absorption of rf energy with no reflection or refraction (adversely affects long distance communications). ACOUSTICS—The science of sound. AMPLITUDE—The portion of a cycle measured from a reference line to a maximum value above (or to a maximum value below) the line. ANGLE OF INCIDENCE—The angle between the incident wave and the normal. ANGLE OF REFLECTION—The angle between the reflected wave and the normal. ANGLE OF REFRACTION—The angle between the normal and the path of a wave through the second medium. ANGSTROM UNIT—The unit used to define the wavelength of light waves. ANISOTROPIC—The property of a radiator to emit strong radiation in one direction. ANTENNA—A conductor or set of conductors used either to radiate rf energy into space or to collect rf energy from space. ARRAY OF ARRAYS—Same as COMBINATION ARRAY. BAY—Part of an antenna array. BEVERAGE ANTENNA—A horizontal, longwire antenna designed for reception and transmission of low-frequency, vertically polarized ground waves. BIDIRECTIONAL ARRAY—An array that radiates in opposite directions along the line of maximum radiation. BROADSIDE ARRAY—An array in which the direction of maximum radiation is perpendicular to the plane containing the elements. CENTER-FEED METHOD—Connecting the center of an antenna to a transmission line, which is then connected to the final (output) stage of the transmitter. CHARACTERISTIC IMPEDANCE—The ratio of voltage to current at any given point on a transmission line. Represented by a value of impedance. COAXIAL LINE—A type of transmission line that contains two concentric conductors. COLLINEAR ARRAY—An array with all the elements in a straight line. Maximum radiation is perpendicular to the axis of the elements. COMBINATION ARRAY—An array system that uses the characteristics of more than one array.