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The microstrip meander-line traveling wave tube (TWT) is a kind of small sized, low voltage, low cost, and easy to fabricate TWT. It is an attractive choice for many applications, such as communication systems, phased array radars, security detectors, and electronic counter measure (ECM) instruments. In this paper, a Ka band U-shape meander-line slow wave structure (SWS) supported by a diamond rod is presented. The dispersion characteristics of this meander-line SWS are analyzed using CST MW Studio. The S-parameter simulation results show that the reflection is below − 15 dB between 32 and 38 GHz, and the particle-in-cell (PIC) simulation reveals that this meander-line TWT can produce 57 W output power at 36 GHz, when it is driven by a 8.1 kV, 0.04 A sheet beam with rectangular cross-sectional area of 1.0 mm × 0.12 mm. This meander-line SWS is manufactured, assembled, and tested. The good agreement between the simulated and measured S11 has been achieved and the mismatch between the simulated and measured S21 has been discussed at the end. [ABSTRACT FROM AUTHOR]

High-power vacuum electron devices (VEDs) are attractive, because of their broad applications, such as advance radars, electromagnetic warfare, and plasma reactors. In this paper, a Ka band mega-watt sheet electron beam traveling wave tube (TWT) is reported. A two-staged rectangular waveguide grating slow wave structure (SWS) driven by a sheet electron beam (20 mm × 1 mm, 164.8 kV, 850 A, 20 ns) is used in this TWT. In order to suppress the self-excited oscillation, a rectangular BeO attenuator is inserted between the two-staged SWSs. The experimental results show that the TWT can produce more than 2 MW output power from 34.2 to 35.5 GHz. And the maximum output power is 4.24 MW at 35 GHz, corresponding to the gain of 25.9 dB. In the future, the TWT will be used to perform research on biomedical effects and imaging. [ABSTRACT FROM AUTHOR]

A staggered vane-shaped slot-line slow-wave structure (SV-SL SWS) for application in W-band traveling wave tubes (TWTs) is proposed in this article. In contrast to the conventional slot-line SWSs with dielectric substrates, the proposed SWS consists only of a thin metal sheet inscribed with periodic grooves and two half-metal enclosures, which means it can be easily manufactured and assembled and has the potential for mass production. This SWS not only solves the problem of the dielectric loading effect but also improves the heat dissipation capability of such structures. Meanwhile, the SWS design presented here covers a −15 dB S11 frequency range from 87.5 to 95 GHz. The 3-D simulation for a TWT based on the suggested SWS is also investigated. Under dual-electron injection conditions with a total voltage of 17.2 kV and a total current of 0.3 A, the maximum output power at 90 GHz is 200 W, with a 3 dB bandwidth up to 4 GHz. With a good potential for fabrication using microfabrication techniques, this structure can be a good candidate for millimeter-wave TWT applications. [ABSTRACT FROM AUTHOR]

A novel Ka-band azimuthal supported angular log-periodic strip-line (ASALS) slow wave structure (SWS) is proposed for a miniature radial sheet beam traveling wave tube (TWT). In the proposed SWS, two dielectric rods are employed to support the ASALS at both azimuthal sides. The strip-line is made of high-melting metal; thus, the ASALS SWS has a higher power capacity than microstrip SWSs. The high-frequency characteristics of that proposed SWS are investigated by using simulation software. The ASALS SWS is then fabricated and assembled for cold test. The measured transmission loss and reflection loss are better than − 2.5 dB and − 10 dB, respectively. The hot performance of the proposed is studied based on particle-in-cell (PIC) simulation. It is shown that when the operating voltage is 5700 V, the ASALS TWT can give a maximum output power of 320 W at the frequency of 39 GHz, corresponding to a gain of 14.9 dB and electron efficiency of 9.12%. [ABSTRACT FROM AUTHOR]

In order to alleviate the problem of achieving large powers beyond 10 kW at frequencies as high as 220 GHz, a two-stage, two-sheet-beam relativistic TWT (SBRTWT) was proposed. For one-stage SBRTWT, there exists instability phenomenon as the effect of electron noise will become large enough compared with the small input power. To avoid the effect, the gain of the first-stage tube was decreased, and its output power was employed to drive the second-stage tube. A large-width branch-guide energy coupler was proposed, analyzed and designed, which can solve the difficult problem to couple the amplified microwave from a wide waveguide to another wide waveguide. A two-beam SBRTWT of 70 kW output with a gain of 28.5 dB was predicted. The findings establish that the two-stage configuration provides larger output powers than the single-stage configuration of SBRTWT and call for further research in two-stage SBRTWT. [ABSTRACT FROM PUBLISHER]

In order to further improve the output power of W-band traveling wave tube (TWT), a low gain TWT was proposed as a secondary amplifier. It uses a double staggered grating slow wave structure (DSG-SWS) and a sheet beam. Firstly, the design of DSG-TWT was given. Through simulation, the DSG-TWT could provide a saturation output power of more than 1000 W in the frequency range of 93–97 GHz, and the maximum output power could reach 1200 W at 95 GHz. No oscillation and current interception were found. Then DSG-SWS was fabricated by E-plane partition method using high-precision CNC milling. The SWS was fed with a high-power input-output coupler which consists of a mode converter and an impedance transformer. Simulation and cold-test results were presented, showing that the S11 is less than −10 dB and the voltage standing wave ratio (VSWR) is less than 2.0 in the frequency range of 93–100 GHz. [ABSTRACT FROM AUTHOR]

A novel slow wave structure (SWS) named angular log-periodic meander-line is proposed for a radial traveling wave tube (TWT). In this paper, a 30 log-periods microstrip angular log-periodic meander-line SWS is studied. The dispersion of this kind of SWS is weak, which shows that it can work in a wide operating bandwidth. The more important advantage is that the operating voltage is much lower than that of the conventional TWT at the same operating frequency and the geometrical dimension is also much smaller than that of the conventional TWT. The beam–wave interaction of the angular log-periodic meander-line TWT is calculated using the particle-in-cell method. When the operating voltage is 1624 V, this kind of TWT can give 156.5-W output power at 35 GHz, the gain is 21.9 dB, and the electron efficiency is \sim17.7\%. With this kind of TWT as mentioned, the concept of radial integrated angular log-periodic meander-line TWT is proposed, which can provide a new way to obtain higher output power. [ABSTRACT FROM PUBLISHER]