Design and analytical modeling of folded waveguide traveling wave tube

Abstract

We are developing a simple analytical model for the design of the folded waveguide traveling wave tube (FWTWT). Numerical software does exist for the design of FWTWT but requires large computer run time, is costly and does not provide the physical view for rapid design optimization of the FWTWT. In this paper, the design and analysis of the FWTWT using the spatial harmonics method of the TE10 mode of the EM wave are presented. An X-band FWTWT is used to verify this method. The normalized dispersion and beam line equations are used to simplify the design process so that the FWTWT can be designed to operate at any desired frequency. Both the S parameter-ABCD-S parameter conversion method and the equivalent circuit model method using Marcuvitz theorem are used for deriving the S parameters and for the analysis of dispersion curve of the 90° sharp-cornered bend of the FWTWT. The analysis is developed by considering the straight and curved portions of the structure supporting the TE10 mode of the EM wave.