Abstract: A traveling wave tube designed to operate as an amplifier within plural frequency bands, which includes a microwave line through which electrons travel and in which a signal is amplified. The microwave line includes, in succession, an input section separated from a succession of gapped output sections, each output section working within one of the operating frequency bands of the traveling wave tube. The input section, connected at one end to an input for injecting the signal to be amplified, works within a frequency band encompassing the operating frequency bands of the traveling wave tube and is intended to preamplify the signal to be amplified. The succession of output sections receives the preamplified signal, each of the output sections being intended to amplify it if the signal is at a frequency lying within its working frequency band and to let it pass through virtually without any interaction if it is at a frequency outside its working frequency band.

Abstract: A helix-type delay line borne by a conical surface. The internal surface of a sleeve has grooves into which are inserted dielectric supports of constant height that are affixed to the helix-type delay line, and the depth of the grooves increases with the diameter of the line.

Abstract: A delay line for a high frequency tube that is cooled by circulating fluid.The cooling fluid circulates in a duct (FIG. 3, 10), formed in the space between two sleeves (8 and 9). The sleeves are of non-magnetic material, impervious to the cooling fluid, and have an axis parallel to the axis of the delay line. The first sleeve (8), is vacuum tight, brazed or hard soldered to dielectric supports (2) and, in cross section connects two adjacent supports in a straight line. The second sleeve (9), is cylindrical, and contains the first sleeve to which it is brazed at several points. A focusing device made of permanent magnets is mounted on the second sleeve.The invention will find use in high frequency tubes.