Planar slow-wave structures for miniaturized low-voltage Cherenkov devices

摘要

Microfabricated vacuum power amplifiers and oscil-lators operating at THz frequencies have attracted a greatinterest. Among them, linear-beam Cherenkov devicessuch as travelling-wave tubes (TWT) and backward-waveoscillators (BWO) have been actively studied. For minia-turized devices, a possibility of low-voltage operation isof primary importance, since decrease of voltage allowsreduce of size and weight of the device. In particular,promising planar slow-wave structures (SWSs) utilizing ametallized meander mi-crostrip line on a dielectric sub-strate has been proposed [1]. Later, similar SWSs havebeen considered in [2–4].In this paper, we present the results of numerical si-mulation, fabrication, and cold measurement of the mi-crostrip meander-line and interdigital SWSs. Schematicsof the SWSs are shown in Fig. 1(a) and Fig. 1(b), respec-tively. Fig. 1(c) shows qualitative drawing of their disper-sion diagrams. One can see that the meander and interdi-gital SWS are suitable for TWT and BWO operation,respectively. The proposed structures exhibit high slow-down factor that is profitable for low-voltage operation.