摘要 |
In a rigid electromagnetic waveguide, reinforcing elements (e.g. glass fibres) or one or more layers of the reinforcing wall extend lengthwise, preferably parallel to the waveguide axis, throughout the length of the waveguide. Preferably in the outermost layer or in outer layers of the reinforcing wall reinforcing elements extend helically about the waveguide. The longitudinally extending reinforcing elements are preferably applied to a stationary mandrel, which may be arranged vertically, through an annular guide which travels to and fro along the length of the mandrel, the elements being retained at the start and finish of each pass of the guide. The resistance of the waveguide to bending when supported horizontally is increased. |