Abstract: A structure to eliminate non-fundamental space harmonics in helical traveling wave tubes is disclosed. A sever of moderate attenuation is produced by way of a conductive surface on nonconductive rods supporting a helical conductor in a traveling wave tube. In addition, the radius and pitch of the helical conductor are simultaneously varied over a short distance to improve the efficiency and performance of the tube.

Abstract: A structure to eliminate non-fundamental space harmonics in helical traveling wave tubes is disclosed. The helix radius and pitch are simultaneously varied over a short distance to improve the efficiency and performance of the tube. This new geometry, an adverse space harmonics taper (ASHT), renders the fundamental phase velocity invariant to frequency and distance effects, while adversely affecting all other space harmonics. Another aspect of the invention reduces the temperature of the helix and further improves tube efficiency, so that electronic efficiencies approach 30% in a linear performance region.

Abstract: It is an object of the invention to provide a miniature traveling wave tube which will have most of the advantages of solid state circuitry but with higher efficiency and without being highly sensitive to temperature and various types of electromagnetic radiation and subatomic particles as are solid state devices.The traveling wave tube which is about 2.5 cm in length includes a slow wave circuit (SWS) comprising apertured fins with a top cover which is insulated from the fins by strips or rungs of electrically insulating, dielectric material.Another object of the invention is to construct a SWS of extremely small size by employing various grooving or etching methods and by providing insulating strips or rungs by various deposition and masking techniques.

Abstract: The disclosed microwave distributed amplifier includes a plurality of cascaded field emission triodes, each having a field emission element for emitting electrons, a grid disposed downstream from the field emission element along the electron flow path and an anode disposed further downstream along the electron flow path. A series of inductive strips interconnect successive grids to form a grid transmission line, while another series of inductive strips interconnect successive anodes to form an anode transmission line. Small electron transit times over integrated circuit distances in a vacuum environment and low interelectrode capacitance allow extremely large gain-bandwidth products to be achieved.

Abstract: The object of the invention is to provide a traveling wave tube with increased linearity to avoid intermodulation of signals being amplified. In a traveling wave tube 10, as shown in FIG. 1, the slow wave structure is a helix (18) including a sever (21). A dynamic velocity taper is provided by gradually reducing the spacing (26) between the repeating elements of the slow wave structure which are the windings of helix (18). The reduction takes place between Zo indicated by line 23 and Z.sub.s which coincides with the output point of helix (18) as indicated by the line (22). The spacing (26) begins to decrease at Z.sub.o and is decreased by up to about 5% at Z.sub.s. The spacing (26) between the repeating elements of the slow wave structure is ideally at an exponential rate because the curve (27), as shown in FIG. 3, increases from Z.sub.o to Zs the point of maximum efficiency and power, at an exponential rate. FIG. 3 shows a coupled cavity traveling wave tube having cavities 32 through 37.

Abstract: A ladder circuit especially useful in backward wave oscillators operating in the 500 GHz to 2,000 GHz range comprises a waveguide (10) having disposed therein transversely oriented slabs (16) which contact an upper wall (22) of waveguide (10). The edges of slabs (11) adjacent the physical center of waveguide (10) along which is directed an electron beam (19) have respective curved segments (11) and stubs (12) and (13) of electrically conductive, non-magnetic material supported thereon. The ends of slabs (16) include metal layers (17) and (18) at respective opposite ends to provide a conductive leakage path. A ridge bar (20) is attached to the inside of the bottom wall (21) of the waveguide (10) and includes a concave upper surface which partially straddles electron beam (19). The inside width of the waveguide (10) is approximately one-half wavelength as determined by the frequency of operation of the backward wave oscillator.

Abstract: An improved slow wave circuit especially useful in backward wave oscillators includes a slow wave circuit (10) in a waveguide (12) as shown in FIG. 1. The slow wave circuit is comprised of rings 11 disposed between and attached to respective stubs (13,14). The stubs (13,14) are attached to opposing sidewalls of the waveguide (12).To the end that opposed, interacting magnetic fields will be established to provide a very high coupling impedance for the slow wave structure, axially orientated bars (20) are connected between rings in alternate spaces and adjacent to the attachment points of stubs 13. Similarly, axial bars (21) are connected between rings in the spaces which do not include bars (20) and at points adjacent to the attachments of bars (21).FIG. 2 shows the current loops (22,23) available because of the inventive structure.FIG. 3 shows that rings 11 may be half rings of 180.degree. arc.FIG. 4 illustrates that the rings or half rings (11) with stubs (13,14) may be formed of flat metal ribbons.

Abstract: An improved R.F. transmitting tube for the 20 GHz to 500 GHz range comprises a gyrotron (10) and a multistage depressed collector (11) as shown in FIG. 1. A winding (19) provides a magnetic field which acts on spent, spinning or orbiting electrons changing their motion to substantially forward linear motion in a downstream direction.The spent electrons then pass through a focusser (18) into the collector (11). Nearly all of the electrons injected into the collector will remain within an imaginary envelope designated by dashed lines 8 and 9 as they travel forward toward the end collector plate (26). The apertures in the collector plates (22-25) are at least as large in diameter as the envelope (8,9) at any particular axial position.FIG. 2 illustrates magnetic field strength from the cathode (13) of FIG. 1 to the collector entrance in focusser 18.

Abstract: The object of the invention is to provide a depressed collector which captures the spent electrons of a microwave transmitting tube at high efficiency in both high and low power modes of operation.The collector comprises entrance and end electrodes (14 and 18, respectively), electrode (18) having a spike extending toward entrance electrode (14). Intermediate electrodes (15, 16 and 17) and the entrance electrode (14) each have a central aperture and, together, these electrodes capture most high power mode spent electrons. The apertures of the electrodes (14-17) increase in size in a downstream direction.To capture low power mode spent electrons a low power mode electrode (19) is positioned between the last intermediate electrode (17) and the end electrode (18). This electrode (19) has a central aperture preferably smaller but no larger than that of electrode (17).