Performance improvement of helix TWT using metamaterial helix-support structure

Abstract

An analysis to determine performance parameters for dispersion characteristics and interaction impedance of helix traveling-wave tube using metamaterial is presented. The conventional positive dielectric supports of the helix slow-wave structure have been replaced by an equivalent homogeneous metamaterial medium. The analysis has been carried out in tape helix model, to include the effects of space harmonics. Structure characteristics, namely, dispersion and interaction impedance have been studied, as the former predicts the phase velocity of the RF wave and the latter has direct relevance to the device gain. It has been observed that, with metamaterial supported helix, both phase velocity and interaction impedance increase as compared to conventional positive dielectric supports. The results have been presented for fundamental space harmonic mode.

Acknowledgment

The authors would like to thank Dr Chandra Shekhar, Director, CSIR-CEERI, Pilani for giving us an opportunity to work in this new and challenging topic.