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Resistive thin-film coatings as an alternative to classical slow wave structures in millimeter-wave vacuum electron devices

We consider the results of modern scientific literature review on the experience and possibilities of using resistive thinfilm layers in vacuum electron devices (resistive wall amplifier). Such thin-film layers can be used as analogue of conventional slow wave structures in vacuum microwave amplifiers. The disadvantages of conventional slow wave structures in millimeter and submillimeter wavelength ranges are discussed. The main advantages and features of resistive thin-film layers, which could be serve as slow wave structures in amplifying devices of vacuum microwave electronics of millimeter and submillimeter wavelength range, are revealed. The proposed review covers the period from 1953, when the idea of a resistive wall amplifier was first introduced, to 2018. It was shown that the majority of literature consist only theoretical results, only a few papers consider the experimental results. Also it is noted that the focus of modern study shifts to the using of metamaterials as a resistive thin-film layer, very promising theoretical results and some cold measurements were obtained only in the GHz region.