Equivalent circuit analysis of a planar helix slow-wave structure for application in high frequency traveling-wave tubes

A planar helix slow-wave structure comprised of a pair of unidirectionally conducting screens was analyzed for its equivalent circuit parameters. These parameters were interpreted for the structure dispersion characteristics and, subsequently, the structure interaction impedance and the Pierce´s gain parameter of a planar-helix TWT. For identical situations with respect to the structure parameters, the present analysis of the planar helix predicted a lower phase velocity, higher interaction impedance, and, consequently, a larger Pierce´s gain parameter and hence a greater promise for a higher device efficiency over a wide frequency range than the conventional circular helix.