A system for positioning a reflector, comprising: a base; a yoke mounted on the base for rotation about a first axis in relation to the base, the yoke supporting the reflector so that the reflector can rotate about a second axis in relation to the yoke; and a linkage comprising at least one connecting rod and a push-pull link, wherein the connecting rod is pivotally coupled at its first end to the push-pull link and mechanically coupled at its second end to the reflector, wherein the linkage is operable to rotate with the yoke about the first axis; characterized in that the system further comprises a worm gear-set that is configured to drive the linkage for movement in relation to the yoke, wherein the worm gear-set comprises a worm and a pawl, the pawl being rotatably mounted within the push-pull link, and wherein the pawl engages the worm so that relative movement between the worm and the pawl imparts translational movement to the pawl and to the push-pull link in a direction along the first axis, parallel to the axial length of the worm, and wherein the push-pull link, while in motion, is adapted to impart movement to the first end of the connecting rod, so that movement of the linkage in relation to the yoke imparts rotation to the reflector about the second axis; and in that the worm is rotatable about the first axis by an elevation control motor that remains substantially stationary with respect to rotation about the first axis while the linkage and the yoke rotate about the first axis, and wherein the movement of the linkage varies responsive to a movement of the elevation control motor in accordance with a relationship that is approximately linear; and wherein the worm is a double cut worm comprising a pair of transverse helical grooves (155a, 155b) forming double helices that are connected at opposing ends of the worm by a transitional part of the grooves having a curved or straight contour, wherein the grooves (155a, 155b) are cut so that the rotation of the worm in one direction guides the pawl along the length of a first helical groove in a first direction aligned with the first axis, and a further rotation in the same direction guides the pawl through the transitional part to engage with a second helical groove and to make the pawl travel in an opposite direction also aligned with the first axis. a base; a yoke mounted on the base for rotation about a first axis in relation to the base, the yoke supporting the reflector so that the reflector can rotate about a second axis in relation to the yoke; and a linkage comprising at least one connecting rod and a push-pull link, wherein the connecting rod is pivotally coupled at its first end to the push-pull link and mechanically coupled at its second end to the reflector, wherein the linkage is operable to rotate with the yoke about the first axis; characterized in that the system further comprises a worm gear-set that is configured to drive the linkage for movement in relation to the yoke, wherein the worm gear-set comprises a worm and a pawl, the pawl being rotatably mounted within the push-pull link, and wherein the pawl engages the worm so that relative movement between the worm and the pawl imparts translational movement to the pawl and to the push-pull link in a direction along the first axis, parallel to the axial length of the worm, and wherein the push-pull link, while in motion, is adapted to impart movement to the first end of the connecting rod, so that movement of the linkage in relation to the yoke imparts rotation to the reflector about the second axis; and in that the worm is rotatable about the first axis by an elevation control motor that remains substantially stationary with respect to rotation about the first axis while the linkage and the yoke rotate about the first axis, and wherein the movement of the linkage varies responsive to a movement of the elevation control motor in accordance with a relationship that is approximately linear; and wherein the worm is a double cut worm comprising a pair of transverse helical grooves (155a, 155b) forming double helices that are connected at opposing ends of the worm by a transitional part of the grooves having a curved or straight contour, wherein the grooves (155a, 155b) are cut so that the rotation of the worm in one direction guides the pawl along the length of a first helical groove in a first direction aligned with the first axis, and a further rotation in the same direction guides the pawl through the transitional part to engage with a second helical groove and to make the pawl travel in an opposite direction also aligned with the first axis.