A 3-D Finite-Element Eigenvalue Analysis of Slow-Wave Structures of Traveling-Wave Tubes Without Matching Meshes

A novel 3-D finite-element modeling technique without matching meshes for the eigenvalue analysis of arbitrary lossy slow-wave structures (SWSs) of traveling-wave tubes is presented. By simulating two examples, it is shown that the cold parameters of SWSs can be accurately and quickly obtained without matching meshes when using this technique. Moreover, a new second-order transverse electric periodic boundary condition (PBC) is proposed to improve the modeling efficiency of lossy SWSs in the nonmatching meshes case, and this technique is very suitable for application of the rotated PBC. This technique would make the modeling of SWSs more flexible, cheaper, and more efficient.