Duration: 36 months
High Power Amplifiers (HPAs) based on vacuum technology are gaining an increasing interest in the context of Low Earth Orbit (LEO) Constellations, since they play an important role in the field of new generation telecommunications systems. The proposed research activity is focused on the study of new vacuum amplification devices operating in the 17-21 GHz frequency range, with a high degree of miniaturization, able to overcome the limits of solid-state solutions and to meet the following specifications: extremely low operation voltage (around 1 KV); saturated power of 10-20 W; total efficiency > 50%; mass < 500 g; gain > 30 dB. As the operating frequency increases, the size of the TWTs becomes smaller and smaller and therefore it is necessary to employ micro-manufacturing processes. The circular helix is one of the most widely used slow-wave interaction structures in TWTs, thanks to its wide bandwidth and high interaction impedance. However, its circular geometry does not allow its production by means of micro-fabrication techniques. To solve this problem, planar interaction structures have been introduced [1-9]. The proposed research activity aims at fabricating a planar helix slow-wave structure (PH-SWS), as shown in the attached figure. PH-SWS have been already reported in the literature, but they have been designed for operation in frequency ranges different from 17-21GHz [3-9]. In addition, the abovementioned specification concerning the extremely low operation voltage has not been met by similar structures operating in the Ka-band. One of the main goals of the proposed activity is to design a PH-SWS structure with strongly innovative features, so as to satisfy the performance requirements and to facilitate the technological realization process. Moreover, we also propose to study the use of a rectangular electron beam (sheet beam) and of an electron gun able to supply it, in order to optimize the interaction between this beam and the PH-SWS.
