Provided are a slow wave circuit and a traveling wave tube suitable for an increase in fineness with regard to processing beam holes, and suitable for higher frequencies. A slow wave circuit (10) includes a meandering waveguide (1) and a beam hole (2) that pierces the meandering waveguide (1), and the cross-section of the beam hole (2) in the direction orthogonal to the long direction is in the shape of a polygon having a larger number of sides than a quadrilateral.

Provided are a slow wave circuit and a traveling wave tube suitable for an increase in fineness with regard to processing beam holes, and suitable for higher frequencies. A slow wave circuit (10) includes a meandering waveguide (1) and a beam hole (2) that pierces the meandering waveguide (1), and the cross-section of the beam hole (2) in the direction orthogonal to the long direction is in the shape of a polygon having a larger number of sides than a quadrilateral.

A folded-waveguide slow-wave structure equipped with an internal load, includes a central plate comprising a rectilinear beam tunnel of same direction as the longitudinal axis of the central plate, and a serpentine-shaped folded slit having its folds in the direction of the width of the waveguide; a lower plate and an upper plate closing the waveguide, the plates being placed on and under the central plate, respectively; at least one groove of cross section that may be variable, produced along the longitudinal axis of the waveguide, in at least one face internal to the waveguide of the lower plate, the upper plate or the central plate, and at least partially comprising a lossy material; in order to form a closed slow-wave structure through which propagates a hybrid slow wave the amplitude of which is attenuated by at least 20 dB between the start and the end of the portion of the one or more grooves containing a lossy material.

A folded-waveguide slow-wave structure equipped with an internal load, includes a central plate comprising a rectilinear beam tunnel of same direction as the longitudinal axis of the central plate, and a serpentine-shaped folded slit having its folds in the direction of the width of the waveguide; a lower plate and an upper plate closing the waveguide, the plates being placed on and under the central plate, respectively; at least one groove of cross section that may be variable, produced along the longitudinal axis of the waveguide, in at least one face internal to the waveguide of the lower plate, the upper plate or the central plate, and at least partially comprising a lossy material; in order to form a closed slow-wave structure through which propagates a hybrid slow wave the amplitude of which is attenuated by at least 20 dB between the start and the end of the portion of the one or more grooves containing a lossy material.

A folded-waveguide slow-wave structure equipped with an internal load, includes a central plate comprising a rectilinear beam tunnel of same direction as the longitudinal axis of the central plate, and a serpentine-shaped folded slit having its folds in the direction of the width of the waveguide; a lower plate and an upper plate closing the waveguide, the plates being placed on and under the central plate, respectively; at least one groove of cross section that may be variable, produced along the longitudinal axis of the waveguide, in at least one face internal to the waveguide of the lower plate, the upper plate or the central plate, and at least partially comprising a lossy material; in order to form a closed slow-wave structure through which propagates a hybrid slow wave the amplitude of which is attenuated by at least 20 dB between the start and the end of the portion of the one or more grooves containing a lossy material.

A folded-waveguide slow-wave structure equipped with an internal load, includes a central plate comprising a rectilinear beam tunnel of same direction as the longitudinal axis of the central plate, and a serpentine-shaped folded slit having its folds in the direction of the width of the waveguide; a lower plate and an upper plate closing the waveguide, the plates being placed on and under the central plate, respectively; at least one groove of cross section that may be variable, produced along the longitudinal axis of the waveguide, in at least one face internal to the waveguide of the lower plate, the upper plate or the central plate, and at least partially comprising a lossy material; in order to form a closed slow-wave structure through which propagates a hybrid slow wave the amplitude of which is attenuated by at least 20 dB between the start and the end of the portion of the one or more grooves containing a lossy material.

A slow-wave circuit is provided with a folded waveguide and a beam hole. The beam hole is arranged between an edge and a center in the direction of width of the folded waveguide. The beam hole is preferably arranged at an edge in the direction of width of the folded waveguide, at a position that does not protrude beyond the folded waveguide. The beam hole is preferably arranged at a position separated by a prescribed distance from the edge in the direction of width of the folded waveguide.

A slow-wave circuit is provided with a folded waveguide and a beam hole. The beam hole is arranged between an edge and a center in the direction of width of the folded waveguide. The beam hole is preferably arranged at an edge in the direction of width of the folded waveguide, at a position that does not protrude beyond the folded waveguide. The beam hole is preferably arranged at a position separated by a prescribed distance from the edge in the direction of width of the folded waveguide.

A slow waveguide for travelling wave tube includes a central plate comprising a beam slip hole, rectilinear in the same direction as the longitudinal axis of the central plate, a bottom plate and a top plate closing the waveguide, respectively arranged on and under the central plate, and a slit folded in the form of a snake having its folds in the direction of the thickness of the guide.

A slow waveguide for travelling wave tube includes a central plate comprising a beam slip hole, rectilinear in the same direction as the longitudinal axis of the central plate, a bottom plate and a top plate closing the waveguide, respectively arranged on and under the central plate, and a slit folded in the form of a snake having its folds in the direction of the thickness of the guide.