Metamaterial mode converter

The invention discloses a metamaterial mode converter and belongs to the field of microwave transmission. The metamaterial mode converter comprises an inner conductor, an outer conductor and a metamaterial, wherein the inner conductor is cylindrical, the outer conductor is barrel-shaped, and the inner conductor is inserted into the outer conductor, and is coaxial with the outer conductor; the metamaterial is constituted by metal array elements cyclically distributed along the axial direction and is connected to the inner wall of the outer conductor; the sizes of the inner and outer conductors are adjustable, the number of cycles and the size of the metal array elements of the metamaterial are adjustable; and the mode converter disclosed by the invention has a compact structure, higher power capacity and can finish the mode conversion within the length of about one third of the wavelength on the premise that the lateral dimension of the system is not increased, so that the metamaterial mode converter can be well applicable to compact type narrow band high-power microwave transmission and emitting systems with small sizes and light weights.