Automated and Manually Operated Antenna Masts. The Com-Power AM series antenna masts are motorized and designed for EMI testing. Antenna mast Model AM-400 allows antenna height variation from 1 to 4 meters, and Model AM-600 can vary antenna height from 1 to 6 meters. They are constructed using non conductive fiber glass material. The antenna is mounted on a one piece cross boom, which is attached to a slider assembly. The slider assembly rides over the length of the mast on delrin wheels. It is pulled by a rope and pulley mechanism powered by a electric motor. The slider assembly is equipped with a spring loaded braking mechanism to prevent inadvertent descent should the rope fail.