Control of phase and gain deviations in an octave bandwidth EHF TWT

Handy, R.A.; Puri, Manish

doi:10.1109/iedm.1986.191233

Cited by 3 publications

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“…The parametric regimes of operation have been chosen considering a wide variety of millimeter-wave helix TWTs [23][24][25][26][27][28]. Typical mm-wave helix TWTs operate with QC around 0.5-0.75.…”

Section: Discussionmentioning

confidence: 99%

“…Grow and Gunderson [6] also developed such a closed-form formula for CN, which is valid for relatively higher values of the space-charge parameter QC and the total distributed circuit loss L dB in decibel (QC∼25, L dB ∼200 dB), making the formula applicable to a high power backward-wave oscillator. This motivates us to find a similar closed-form formula valid for relatively lower values of QC and circuit loss L dB (0.5≤QC≤1 and 4≤L dB ≤6, typical for mm-wave TWTs [23][24][25][26][27][28]) that can be used to predict the start-oscillation condition for a TWT used as an amplifier, hereby a method based on an ANN algorithm (Section 2). The analysis further used for studying the backward-wave oscillation start condition of a typical millimeter-wave TWT, and some physical interpretations of the parametric effects are inferred.…”

Section: Introductionmentioning

confidence: 99%

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A Simple Closed-form Formula for Backward-Wave Start-Oscillation Condition for Millimeter-Wave Helix TWTs

Datta

Kumar

Basu³

2008

Int J Infrared Milli Waves

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An accurate and simple closed-form formula, for backward-wave start-oscillation condition for a millimeter-wave helix traveling-wave tube amplifier was developed, using an artificial neural network (ANN) algorithm. The analysis considers the effects of circuit loss and also the variation of electron beam diameter corresponding to beam filling. The formula is simple and amenable to easy computation, even using a scientific calculator, and without resorting to exhaustive numerical iterative search followed in conventional analyses and, at the same time, without sacrificing the accuracy in results. The formula was validated against published results, and excellent accuracy was observed. The analysis has been further used for inferring some physical interpretations on the effects of beam-filling factor and circuit loss on the start-oscillation condition of a typical millimeter-wave helix traveling-wave tube.Keywords Artificial neural network (ANN) . Backward-wave oscillation (BWO) . Backward-wave interaction impedance . Millimeter-wave traveling-wave tube (TWT) Abbreviations ANN artificial neural network BWO backward-wave oscillation EHF extra high frequency mm-wave millimeter-wave SWS slow wave structure TWT traveling-wave tube Int J Infrared Milli Waves (

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Simple Closed-form Formula for Backward-Wave Start-Oscillation Condition for Millimeter-Wave Helix TWTs

Datta

Kumar

Basu³

2008

Int J Infrared Milli Waves

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Vacuum electronics at the dawn of the twenty-first century

1999

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Research of slow-wave circuit CAD of gain and phase matched operation helical TWTs

Yang

2002 3rd International Conference on Microwave and Millimeter Wave Technology, 2002. Proceedings. ICMMT 2002.

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Designing an octave bandwidth helical traveling wave tube for phase and gain matched operation in the EHF region presents many obstacles, the dimensional controls which must be imposed in the design. In this paper, a code, which is based on the sheath model is used to analyzed the effect on dispersion and impedance of several hetical slow-wave circuit parameter variations. including thickness and relative dielectric constant of the support rods, pitch width ,height of the metal vane and helix average radius. The dispersion and impedance are compared for each set of variations. This computational techniques are readily applicable to other TWTs.Despite the existence of a qualitative understanding of the principles of operation, new devices traditional have been designed by scaling the behavior of existing ones using empirical scaling laws. The performance of the scaled device is verified by bench testing and the model device adjusted until design specifcations are achieved.Several such' design-test cycles are often needed to achieve a working device. TWT of gain and phase matched operation has high demand for performance (gain mismatched within and beyond 1.5 dB and phase mismatched within and beyond 20 degree). Based on lot of experiments and theoty analysis, it is said that deviations of helix slow wave suucture(SWS) parameters have main contribution on phase and gain mismatched operation of TWT. This paper will accurately describe effect for dispersion and impedance by simulating, when some parameters of the SWS vary within and beyond the tolerances typically employed within the industry.Helix TWT is extensively applied for broadband high power device, whose SWS consist of a helical metal wire or tape supports by three or more dielectric rods in a conducting barrel. Some metal vanes are necessity for more wide band sometime. The particular device analyzed in the paper is a helical SWS, which is comprise of a tape. dielectric, rods, metal envelope and metal vane, shown in Fig. 1. Several circuit parameters were varied including the support rod width, metal vane height, helix mean radius, pitch and relative dielectric constant of the support rods. The dispersion and impedance are compared for each set of variations. Support rod width -I i-Fig. I T W helical slow-wave circuit 0-7803-7486-X/02/$17.00 (0 2002 IEEE. 186

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Control of phase and gain deviations in an octave bandwidth EHF TWT

Cited by 3 publications

References 0 publications

A Simple Closed-form Formula for Backward-Wave Start-Oscillation Condition for Millimeter-Wave Helix TWTs

A Simple Closed-form Formula for Backward-Wave Start-Oscillation Condition for Millimeter-Wave Helix TWTs

Vacuum electronics at the dawn of the twenty-first century

Research of slow-wave circuit CAD of gain and phase matched operation helical TWTs

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