Structure d'amplificateurs à ondes progressives

836,219. Travelling-wave tubes. STANDARD TELEPHONES & CABLES Ltd. Jan. 8, 1957, No. 713/57. Class 39(1). A travelling-wave tube mounting and focusing unit comprises an input and output rectangular waveguide 9, 10, Fig. 1, respectively, each apertured through their wide walls to surround respectively the input and output ends of tube 1, a focusing solenoid 15 extending between the waveguides and further solenoids 14, 16 at each end beyond the waveguides, and, at least in conjunction with the output waveguide, a pair of sheets 18, 19, Figs. 2, 3, of low reluctance magnetic material apertured to surround the tube, arranged to abut against the outside of the opposite wide waveguide walls 10 and extending beyond the width of the walls; and a pair of similarly-oriented permanent magnets 20 extending between and contacting the pair of said sheets and lying one on each narrow wall of the waveguide. The length of each magnet may be 1¢ times the wide dimension of the waveguide. The sheets 18, 19 are slotted partially at 24 to reduce transverse fields. The permanent magnets maintain a uniform field along the tube.