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Journal ArticleDOI

The Analytical Design of a Folded Waveguide Traveling Wave Tube and Small Signal Gain Analysis Using Madey's Theorem

01 Jan 2009-Progress in Electromagnetics Research-pier (EMW Publishing)-Vol. 98, pp 137-162
TL;DR: In this paper, an analytical model for the design of the folded waveguide traveling wave tube (FWTWT) was developed for the physical view for rapid design optimization of the FWTWT.
Abstract: We are developing an analytical model for the design of the folded waveguide traveling wave tube (FWTWT). This analytical model provides the physical view for rapid design optimization of the FWTWT. The design and analysis of the FWTWT using the spatial harmonics method of the TE10 mode of the EM wave are presented. An X-band FWTWT is used to verify this method. The normalized dispersion and beam line equations are used to simplify the design process so that the FWTWT can be designed to operate at any desired frequency. The small signal gain of an FWTWT is calculated by using Madey's theorem. The results of this analysis are compared with the numerical single particle simulation carried out using MATLAB. The results are in excellent agreement. The Madey's theorem can be used to provide a potential indication of the gain magnitude of the FWTWT.

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Citations
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Journal ArticleDOI
TL;DR: In this article, the surface roughness of metal waveguides has been investigated at the nanoscale using microfabrication techniques, and two significant examples are considered: a 0.346-THz backward wave tube oscillator and an 0.263-thz traveling wave tube.
Abstract: Vacuum electron devices are the most promising solution for the generation of watt-level power at millimeter wave and terahertz frequencies. However, the three-dimensional nature of metal structures required to provide an effective interaction between an electron beam and THz signal poses significant fabrication challenges. At increasing frequency, losses present a serious detrimental effect on performance. In particular, the skin depth, on the order of one hundred nanometers or less, constrains the maximum acceptable surface roughness of the metal surfaces to be below those values. Microfabrication techniques have proven, in principle, to achieve values of surface roughness at the nanometer scale; however, the use of different metals and affordable microfabrication techniques requires further investigation for a repeatable quality of the metal surfaces. This paper compares, for the first time, the nanoscale surface roughness of metal THz waveguides realized by the main microfabrication techniques. In particular, two significant examples are considered: a 0.346-THz backward wave tube oscillator and a 0.263-THz traveling wave tube.

55 citations


Cites methods from "The Analytical Design of a Folded W..."

  • ...The design of a folded waveguide is quite straightforward using analytical methods [24]....

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Journal ArticleDOI
TL;DR: In this article, the azimuthally symmetric TE-mode analysis of the structure was carried out in fleld matching technique by considering the propagating wave in cylindrical free space region having radius equal to the hole-radius of metal disc, and the stationary waves in free-space and dielectric regions between two consecutive metal discs.
Abstract: A circular waveguide loaded with dielectric and metal discs was chosen to evaluate its dispersion characteristics and dispersion shaping with change of structure parameters for wideband coalescence of beam- and waveguide-mode dispersion characteristics for wideband gyro-TWT performance. The azimuthally symmetric TE-mode analysis of the structure was carried out in fleld matching technique by considering the propagating wave in cylindrical free-space region having radius equal to the hole-radius of metal disc, and the stationary waves in free-space and dielectric regions between two consecutive metal discs. The dispersion relation and, in accordance, a computer code were developed. Further, the roots of the dispersion relation for various sets of the structure parameters were obtained using the developed computer code; the dispersion characteristics were plotted; and the dispersion shaping was projected for typically chosen TE01-, TE02- and TE03-modes. The analytical results were validated against those obtained for the conventional and earlier published structures, and also those obtained using commercially available simulation tool. Finally, a study on azimuthal electric fleld available over the radial coordinate was carried out to show the control of structure parameter on the gyrating electron beam position for the chosen operating mode of a dielectric and metal discs loaded gyro-TWT.

31 citations

Journal ArticleDOI
TL;DR: In this paper, a high-power wideband sheet-beam coupled-cavity traveling-wave tube operating at V-band is presented, which employs three-slot doubly periodic staggered-ladder coupled-Cavity slow-wave structure, and a 5:1 aspect- ratio sheet electron beam is used to interact with the circuit.
Abstract: The design and analysis of a high-power wideband sheet- beam coupled-cavity traveling-wave tube operating at V-band is presented The interaction circuit employs three-slot doubly periodic staggered-ladder coupled-cavity slow-wave structure, and a 5:1 aspect- ratio sheet electron beam is used to interact with the circuit Combined with design of the well-matched input and output couplers, a 3-D particle-in-cell model of the sheet-beam coupled-cavity traveling-wave tube is constructed The electromagnetic characteristics and the beam- wave interaction of the tube are investigated From our calculations, this tube can produce saturated output power over 630Watts ranging from 58GHz to 64GHz when the cathode voltage and beam current are set to 132kV and 300mA, respectively The corresponding saturated gain and electron e-ciency can reach over 325dB and 159% Compared with the circular beam devices, the designed sheet- beam TWT has absolute advantage in power capability, and also it is more competitive in bandwidth and electron e-ciency

23 citations


Cites background from "The Analytical Design of a Folded W..."

  • ...to its outstanding combined performances in power capacity and bandwidth, traveling-wave tube (TWT) is one of the most important millimeter-wave amplifiers [2–9]....

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Journal ArticleDOI
TL;DR: In this paper, the beam-present dispersion relation and small-signal gain equation in Pierce's format for the disc-loaded-coaxial waveguide were developed for wideband gyro-traveling-wave tube (gyro-TWT) if the conflgurations are used as interaction structure.
Abstract: The earlier developed combined beam-absent analysis of the disc-loaded-coaxial waveguide in two-conflgurations (part-1) has shown promise for wideband gyro-traveling-wave tube (gyro-TWT) if the conflgurations are used as interaction structure. In the present paper, the beam-present dispersion relation and small-signal gain equation in Pierce's format for the disc-loaded-coaxial waveguide were developed. A broadening of the device bandwidth was presented by disc-loading the coaxial waveguide interaction structure of a gyro-TWT with a comparison against the circular cylindrical waveguide, coaxial waveguide, and disc-loaded circular waveguide in their respective gain- frequency responses obtained by using a numerical computer code on the basis of the present beam-present analysis.

20 citations

Journal ArticleDOI
TL;DR: In this article, a study on a miniature, low voltage, wide bandwidth, and high RF efficiency V-shaped microstrip meander-line slow-wave structure is carried out.
Abstract: A study on a miniature, low voltage, wide bandwidth, and high RF efficiency V-shaped microstrip meander-line slow-wave structure is carried out in this paper. The fabrication of this structure is very convenient by utilizing the 2-D micro-fabrication techniques. Radio-frequency characteristics including dispersion properties, interaction impedance and S-parameters are analyzed. Based on these results, nonlinear large signal performances of the V-shaped microstrip meander-line traveling-wave tube are calculated by 3-D particle-in-cell code. This study shows that this miniature millimeter-wave power amplifier is capable of delivering several tens of watts output power ranging from 127 GHz to 145 GHz.

18 citations

References
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Book
01 Apr 1990

10,459 citations

Book
01 Jun 1965
TL;DR: This paper presents a meta-modelling architecture for waveguiding systems that automates the very labor-intensive and therefore time-heavy and expensive process of designing and installingWaveguiding Systems.
Abstract: Chapter 1: Introduction Chapter 2: Electromagnetic Theory Chapter 3: Transmission Line and Waveguides Chapter 4: Circuit Theory for Waveguiding Systems Chapter 5: Impedence Transformations and Matching Chapter 6: Passive Microwave Devices Chapter 7: Electromagnetic Resonators Chapter 8: Periodic Structures and Filters Chapter 9: Microwave Tubes Chapter 10: Solid State Amplifiers Chapter 11: Parametric Amplifiers Chapter 12: Oscillators and Mixers Appendix One: Useful Relations from Vector Analysis Appendix Two: Bessel Functions Appendix Three: Conformal Mapping Techniques Appendix Four: Physical Constants and Other Data

3,934 citations


"The Analytical Design of a Folded W..." refers background in this paper

  • ...and the coupled-cavity structure have periodic reactive load that can reduce the velocity of the EM wave traveling across the path [18, 19]....

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Book
01 Jan 1951

2,353 citations

Journal ArticleDOI
John R. Pierce1, L.M. Field
01 Feb 1947
TL;DR: In this article, an electron beam traveling with about 1/13 the speed of light is shot through a helical transmission line with about the same velocity of propagation, and the gain was achieved over a bandwidth 800 megacycles between 3-decibel points.
Abstract: Very-broad-band amplification can be achieved by use of a traveling-wave type of circuit rather than the resonant circuit commonly employed in amplifiers. An amplifier has been built in which an electron beam traveling with about 1/13 the speed of light is shot through a helical transmission line with about the same velocity of propagation. Amplification was obtained over a bandwidth 800 megacycles between 3-decibel points. The gain was 23 decibels at a center-band frequency of 3600 megacycles.

317 citations

Journal ArticleDOI
05 Jun 2003
TL;DR: In this paper, the authors present feasibility studies of an oscillator concept using an amplifier with delayed feedback, and experimental evaluation of the concept at 50 GHz is presented, where the results of the experiment are in good agreement with the simulations.
Abstract: Microfabricated folded waveguide traveling-wave tubes (TWTs) are potential compact sources of wide-band, high-power terahertz radiation. We present feasibility studies of an oscillator concept using an amplifier with delayed feedback. Simulations of a 560-GHz oscillator and experimental evaluation of the concept at 50 GHz are presented. Additionally, results from various fabrication methods that are under investigation, such as X-ray lithography, electroforming, and molding (LIGA), UV LIGA, and deep reactive ion etching are presented. Observations and measurements are reported on the generation of stable single-frequency oscillation states. On varying the feedback level, the oscillation changes from a stable single-frequency state at the threshold to multifrequency spectra in the overdriven state. Simulation and experimental results on amplifier characterization and dynamics of the regenerative TWT oscillator include spectral evolution and phase stability of the generated frequencies. The results of the experiment are in good agreement with the simulations.

286 citations


"The Analytical Design of a Folded W..." refers methods in this paper

  • ...The results obtained using the small signal gain analysis using Madey’s theorem would now be compared with the work done by Bhattacharjee [3]....

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  • ...Bhattacharjee has performed simulations on the design of FWTWT sources for Terahertz radiation, using state of the art TWT softwares [3]....

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  • ...Bhattacharjee’s simulations were performed with the state of the art TWT softwares (MAFIA, TW3 and CHRISTINE), and gave an electronic gain of about 13 dB at a frequency of 542 GHz [3]....

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  • ...The FWTWT dimensions used so that the results can be compared with Bhattacharjee’s work [3]....

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  • ...FWTWT uses an electric field plane (E-plane) bend rectangular waveguide, as can be seen in Figure 1 [3]....

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