Novel overmode circular waveguide bend for high power tm01 mode transmission

A novel structure of overmode circular waveguide bend is investigated, which is used to transmitter circular waveguide TM
₀₁
mode with high power-handing capacity, high transmission efficiency and small bend radius. Metal plates and metal rod are used to change the type of waveguide. In the bend of the structure, circular waveguide is split into four sector waveguides, and the phase difference between sector waveguide TE
₁₁
modes changes from 0 to 2π, that means the phases of sector waveguide TE
₁₁
modes are also same after bending. Four sector waveguide TE
₁₁
modes with same phase convert to coaxial TEM mode at the end of the metal plates, which finally converts to circular waveguide TM
₀₁
mode and is outputted. Microwave propagates with singlemode in the bend of the structure, that can avoid exciting high-order mode. Experimental test results show that VSWR is below 1.3 in the range of 8.25-8.55 GHz and less than 1.07 at 8.4 GHz and the insertion loss is 0.2 dB at 8.4 GHz, which prove the feasibility of the structure of the overmode circular waveguide bend.