A modulation domain divider is disclosed that causes the divider output to be attenuated when the divisor input falls below the divisor threshold. The slit penetrates the metal base thicknesswise and extends longitudinally relative to the metal base. The C-axis driving system also includes a C-axis driving motor connected to the worm shaft and serving to rotationally index the spindle to a specified rotational angle. The sheath wave barriers and the shielding device are arranged on a common carrier.