Low noise millimeter wave traveling-wave amplifier

This paper reports the results of a feasibility study aimed at the development of a travelling wave amplifier in the frequency range 35-40 kmc with noise figure less than 15 db. The designs built and tested have emphasized the use of circuits which are large for the frequency range, the sizes varying from ka = 0.1 to ka = 0.4. This is the largest practical size due to the propagation of the TE11 coaxial mode between helix and shield. The smallest tubes have used confined solid beams and have attained noise figures of 13 db. The large tubes will use hollow beams of the Currie-Forster and Magnetron Injection type in the hope of securing lower noise figures and better focusing. Data are given which describe the construction of the tubes and the experimental results obtained. The noise figure values will be correlated with theory, using the methods of R.W. Peter.