HIGH POWER OVER-MODE BENT WAVEGUIDES FOR CIRCULAR TM01 AND COAXIAL TEM MODE TRANSMISSION

Three bent waveguides are proposed and investigated, two for circular waveguide TM01 mode and one for coaxial TEM mode. For high power-handling capacity, all of them are over-mode waveguides. In the bend, circular or coaxial waveguides transmitting only sector waveguide TE11 modes are split into several same sector waveguides by metal plates and metal rod. These sector waveguides are grouped by their lengths. Length differences of sector waveguides lead to phase differences of the sector waveguide TE11 modes after bending. Due to requirements of mode conversion, the phase difference regulated by radii of circular waveguide and metal rod must be 2nπ, n = 0, 1, 2, . . .. Since the phase difference is independent of bend radius, the radius could be as small as possible. One of the prototypes is experimentally verified, and the test results of the VSWR show that simulation has good match to experiment. Insertion loss is 0.2 dB at 8.4 GHz, which proves the feasibility of the prototype.