The present disclosure relates to a communication method and system for converging a 5th-Generation communication system for supporting higher data rates beyond a 4th-Generation system with a technology for Internet of Things. The outer layer forms an outer major surface of the device. Each variable-capacitance unit has a variable-capacitance diode, the electrostatic capacity of which changes according to a direct-current voltage applied between the anode and the cathode. A stator is concentrically surrounding the rotor.