Novel coupled-cavity TWT structure using two-step LIGA fabrication

In order to make millimeter-wave sources practical, improved fabrication methods are required. The use of Lithographie, Galvanoformung, Abformung; German acronym (LIGA) to fabricate a coupled-cavity traveling-wave tube (TWT) is presented. The proposed circuit design will focus on two-step LIGA fabrication and dual in-line ladder structure with a rectangular beam tunnel. The fabrication sequence of two-step LIGA is illustrated and the advantages and tradeoff of this approach are described. Three electromagnetic codes-HFSS, GdfidL, and MAGIC3D-are employed to analyze the circuit characteristics in cold and hot test simulations. Finally, the results from small and large signal analyses are presented to verify the validity of the circuit design.