Mode converters for high-power microwaves

Quite often, the output of high-power microwave sources is extracted in a waveguide mode that is not directly useful to feed an antenna. This makes mode conversion essential at high powers. The power levels can be in the range of a few MW to a GW lasting for a time duration that typically contains hundred cycles of the microwave frequency. We consider the design of two mode converters 1) from TM01 circular to TEM coaxial and 2) TE 10 rectangular to TM01 circular. It is noted that the mode converters are reciprocal devices and can be used in either direction of mode conversion.