A coaxial amplifier having at least one electron beam is provided. The amplifier may include a conductive rod, a plurality of parallel discs on the rod, a cathode array for producing at least one electron beam. When a plurality of electron beams are formed they are arranged in an annular configuration around said rod and disks, and directed along said rod and coaxially thereof. A first waveguide may apply electromagnetic wave energy to one end of said disc and rod assembly to induce propagation of said energy along said assembly. A second waveguide may extract the amplified electromagnetic energy from the other end of the disc and rod assembly.

A coaxial amplifier having at least one electron beam is provided. The amplifier may include a conductive rod, a plurality of parallel discs on the rod, a cathode array for producing at least one electron beam. When a plurality of electron beams are formed they are arranged in an annular configuration around said rod and disks, and directed along said rod and coaxially thereof. A first waveguide may apply electromagnetic wave energy to one end of said disc and rod assembly to induce propagation of said energy along said assembly. A second waveguide may extract the amplified electromagnetic energy from the other end of the disc and rod assembly.

Traveling-wave tube amplifiers for high-frequency signals, including terahertz signals, and methods for making a slow-wave structure for the traveling-wave tube amplifiers are provided. The slow-wave structures include helical conductors that are self-assembled via the release and relaxation of strained films from a sacrificial growth substrate.

Described herein is a traveling wave tube (TWT), comprising an electron gun configured to generate an electron beam (E-beam); a signal injector configured to generate a radio frequency (RF) signal; a slow wave structure (SWS) having an aperture configured to combine the E-beam and the RF signal; an outer wall enclosing the SWS; and at least one electromagnetically-active material on one of (1) at least one projection on at least one of a periphery of the SWS and on a side of the outer wall facing the SWS and (2) the periphery of the SWS configured to receive at least one electromagnetic signal to control, on-the-fly, amplification of the RF signal by maximizing dampening of spurious modes while minimizing dampening of operating modes.

Described herein is a traveling wave tube (TWT), comprising an electron gun configured to generate an electron beam (E-beam); a signal injector configured to generate a radio frequency (RF) signal; a slow wave structure (SWS) having an aperture configured to combine the E-beam and the RF signal; an outer wall enclosing the SWS; and at least one electromagnetically-active material on one of (1) at least one projection on at least one of a periphery of the SWS and on a side of the outer wall facing the SWS and (2) the periphery of the SWS configured to receive at least one electromagnetic signal to control, on-the-fly, amplification of the RF signal by maximizing dampening of spurious modes while minimizing dampening of operating modes.

Traveling-wave tube amplifiers for high-frequency signals, including terahertz signals, and methods for making a slow-wave structure for the traveling-wave tube amplifiers are provided. The slow-wave structures include helical conductors that are self-assembled via the release and relaxation of strained films from a sacrificial growth substrate.

Miniature slow-wave transmission lines are described having an asymmetrical ground configuration. In some embodiments, the asymmetrical ground configuration facilitates a reduction in size. Non-uniform auxiliary conductors may be disposed above or below the co-planar waveguide to facilitate a reduction in the length of the miniature slow-wave transmission lines. Phase shifters may be implemented having a reduced size by including one or more miniature slow-wave transmission lines.

Miniature slow-wave transmission lines are described having an asymmetrical ground configuration. In some embodiments, the asymmetrical ground configuration facilitates a reduction in size. Non-uniform auxiliary conductors may be disposed above or below the co-planar waveguide to facilitate a reduction in the length of the miniature slow-wave transmission lines. Phase shifters may be implemented having a reduced size by including one or more miniature slow-wave transmission lines.

A slow-wave circuit comprises: a waveguide comprising a meander-shaped part that transmits an electromagnetic wave and alternately repeats a first folded part and a second folded part folded onto the opposite side to the first folded part; and a beam hole that transmits an electron beam, extends in a predetermined direction, and penetrates the meander-shaped part, wherein the beam hole penetrates the meander-shaped part so that a part of the beam hole protrudes from the first folded part.

A slow-wave circuit comprises: a waveguide comprising a meander-shaped part that transmits an electromagnetic wave and alternately repeats a first folded part and a second folded part folded onto the opposite side to the first folded part; and a beam hole that transmits an electron beam, extends in a predetermined direction, and penetrates the meander-shaped part, wherein the beam hole penetrates the meander-shaped part so that a part of the beam hole protrudes from the first folded part.