Coaxial transmissioin line input transformer having externally variable

Abstract

An input transformer for a coaxial transmission line is provided which allows continuously variable amplitude and phase of an RF signal conducted on the transmission line. The transformer comprises a housing having a longitudinal axis. A center conductor of the coaxial line extends along the axis through the housing. A first sleeve is axially movable within the housing, and has contact points on an outer surface thereof to provide electrical conductivity between the first sleeve and the housing. The ability of the first sleeve to move axially enables variability in the location of the transformer along the transmission line. The first sleeve has an inner wall that is eccentric relative to the longitudinal axis of the center conductor. A second sleeve having a cylindrical outer wall is disposed within the first sleeve. The second sleeve is rotationally movable within the first sleeve, and has contact points on the outer wall to provide electrical conductivity between the first sleeve and second sleeve. The second sleeve has an inner wall that is eccentric with the outer wall of the second sleeve. Rotation of the second sleeve within the first sleeve varies the eccentricity of the inner wall of the second sleeve relative to the center conductor to alters the impedance (Z.sub.0) of the input transformer. The transformer may be adjusted in position and impedance without dismantling the transmission line system, permitting an associated adjustment of phase and amplitude of an RF signal conducted on the transmission line.