Abstract: An extendable column consisting of a plurality of axially elongated rigid structural sections nested within one another. Each section includes a plurality of screws running the length thereof and rotatably attached therein. The next inner section includes threaded lugs oriented to threadingly engage the screws thus resulting in extension or retraction of the column upon rotation of the screws. The screws of each section are selectively rotated by a motor and an engagement mechanism.

Abstract: An antenna pedestal for producing angular motion is formed of a base and upper and lower subassemblies. Pivot arrangements are provided between the base and the lower subassembly for enabling the lower subassembly to be angularly displaced with respect to the base about a pair of parallel axes by a pair of linear actuators which are connected between the base and the lower subassembly. The first of these actuators rotates the lower pedestal through a first arc sector and the other rotates the lower subassembly in a second arc sector which is in a common plane with the first arc sector. Likewise, the upper subassembly is supported on the lower subassembly with pivot arrangements located therebetween for enabling the upper subassembly to be angularly displaced with respect to the lower subassembly about a further pair of parallel axes which are orthogonal with the pair of axes about which the lower subassembly is displaced relative to the base.

Abstract: Apparatus for positioning a rotatable element. A plurality of linear actuators are used to provide rotational positioning thereof to any selected point along an arc extending through greater than 180.degree.. In one embodiment, two pair of linear actuators provide rotation about respective perpendicular axes to thereby accomplish X/Y positioning over an entire hemisphere.