Attenuation of the TE01 Wave Within the Curved Helix Waveguide

| If the system of cylindrical coordinates, in which the cylindrical waveguide ordinarily is described, is bent in the same way as the axis of the curved waveguide, Maxwell's equations change. Jouguet 1 has shown an approximate solution of Maxwell's equations written in a system of toroidal coordinates. This solution may be applied to calculate the field pattern of a TE 0 i wave in the curved helix waveguide."' The waveguide 3 consists of a helix made of very thin wire and a coating of a lossy dielectric which may be shielded by a metallic pipe. The lossy dielectric serves to suppress unwanted modes which may be excited in the helix waveguide. Although the lossy dielectric does not affect the TE 0 i wave in a perfectly straight guide, it does give rise to an additional attenuation if the waveguide is bent. It is the purpose of the present paper to show how a helix waveguide should be designed in order to keep this additional attenuation as low as possible. On the other hand, the attenuation of the TEoi wave in bends is not the only effect, which is to be considered * The author used the same method of analysis to calculate the attenuation and field structure of the TEoi wave in a curved spaced-ring type waveguide while he was working with the Siemens and Halske Company in Germany. 1649