@article{Datta_2009, title={Backward-Wave Oscillation Criterion in a Step-Tapered Helix Travelling-Wave Tube}, volume={59}, url={https://publications.drdo.gov.in/ojs/index.php/dsj/article/view/1484}, DOI={10.14429/dsj.59.1484}, number={1}, journal={Defence Science Journal}, author={Datta, S.}, year={2009}, month={Jan.}, pages={49-54} }