Analysis of the Bottom Metal/Dielectric Supporting Plane in Meander Line Slow Wave Structures for Millimeter Wave Traveling Wave Tubes

Meander lines have been lately studied as slow wave structures (SWSs) for millimeter-wave traveling wave tubes (TWTs) given their numerous benefits such as low beam voltage, high interaction impedance and straightforward manufacture. They are seen as a very promising candidate for a new generation of low-cost TWTs. The efforts are now focused on finding novel meander line configurations that could improve the overall performance of the TWT. This paper analyses the effect of the material underneath the meander line substrate and presents different alternatives to enhance the interaction impedance.