Design of Ka-band high power TM_0n-TEM hybrid modes convertor

Overmoded Ka-band high power microwave (HPM) sources with high energy efficiency can not ensure the output modes purity, which are generally mixedTM0n modes. However, it is necessary for high radiation efficiency that the microwave input to the ready-made radiation terminal is a certain single mode. So it is hard to put these HPM sources into application. In this paper, a hybrid modes converter, utilizing outer and inner coaxial waveguides to purify TM0n mixed modes with high power handing capacity, is proposed. With this method, the TM0n(n5) mixed modes can be converted into pure TEM mode with high conversion efficiency, reducing the modes purification difficulty in the design of the overmoded HPM sources.