The design of serpentine-mode converters for high-power microwave applications

In this paper, we report the design methodology and numerical results for two mode converters that are suitable for high-power microwave applications. Both converters are designed to operate at 11.424 GHz and utilize periodic serpentine structures to convert between modes with different azimuthal-mode indexes. The first converts about 98.5% of an incident linearly polarized TE12 mode to the TE01 mode when oriented as an H-plane bend, but has just 1% mode conversion to all modes when oriented as an E-plane bend, The second device converts a linearly polarized TE11 mode to a TM01 mode with over 99.99% effectiveness, The performance of both devices with respect to parametric variations is detailed. Experimental measurements of the radiation patterns from the TE12-to-TE01-mode converter are consistent with the theoretical predictions.