Mode converter for microwave power transmission circuit

A mode converter for microwave power transmission circuits, working at high power, interposed between an electromagnetic wave generator and a circular output waveguide propagating the circular TE.sub.01 mode, said converter comprising:

• a rectangular waveguide, working in its fundamental mode, TE.sub.10, connected by one of its ends to the electromagnetic wave generator and having its other end closed;
• a circular waveguide propagating the TM.sub.01 mode, having a first end connected to the rectangular waveguide by a lateral opening, located on the large side of the rectangular waveguide near its closed end, in such a way that the axes of the two waveguides are perpendicular, said converter further comprising:
• a group of intermediate waveguides, interposed between the circular waveguide propagating the TM.sub.01 mode and the output waveguide, the intermediate waveguides being distributed in a ring before a second end of the circular waveguide propagating the TM.sub.01 mode, each of said intermediate waveguides being realized by a sequence of n waveguide sections working in the rectangular TE.sub.10 mode, the large sides of their cross-sections being gradually offset rotationally with respect to one another, in the same direction, in such a way that the first waveguide section of each intermediate waveguide has at least one of its large sides cut in a substantially perpendicular direction by a radius of the circular waveguide propagating the TM.sub.01 mode, in such a way that the overall offset between the first waveguide section and the last waveguide section of one and the same intermediate waveguide is 90.degree.,