Using whole structure modes in the large-signal modeling of TWTS with arbitrary slow-wave structures

The increasing demand for high-power and broad-band RF sources requires that efficient simulation tools be used in their design and optimization. This demand has led to the development of highly efficient large-signal 2D codes^1,2 suitable for fast and accurate modeling of Travelling Wave Tube (TWT) amplifiers based on such different types of slow-wave structures (SWSs) as coupled-cavity1 and serpentine/folded-waveguide². The success of these 2D models was partially due to the fact that particular code targeted one specific type of slow-wave structure, and this allowed for simplifications in the model description that were specific to the targeted structure. However such simplification becomes a drawback when considering any new type of SWS what requires a new effort to develop a suitable field model and implement it in a large-signal code. To eliminate this drawback we have developed a formulation based on the whole structure modes imported directly from computational electromagnetic codes or generated by using reduced-order simulation approach³.