Space-Harmonic Effects in Helical Slow-Wave Structure --- an Equivalent Circuit Analysis

Ghosh, S. K.; Sinha, A. K.; Gupta, R. K.; Joshi, S. N.; Jain, P. K.; Basu, B. N.

doi:10.2528/pier00011001

Cited by 7 publications

(8 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For the analysis, in the structure model ( Fig. 1(b)), the rectangular-shaped discrete dielectric support rods are azimuthally smoothed out into a single (or a number of) continuous dielectric tube regions, between the helix and the metal segments tip (b ≤ r ≤ c) of an effective permittivity value ε r which is found from the relative volume of the dielectric support rods in the structure [1][2][3]. For practical helical SWS, the dielectric support rods are usually made of APBN (anisotropic pyrolytic boron nitride ε r = 5.1), quartz (ε r = 3.78), beryllia (ε r = 6.65).…”

Section: Discussionmentioning

confidence: 99%

“…1) is field analyzed here to find its dispersion relation and interaction impedance [1][2][3][4][5][6][7][8][9]. The analysis of a loaded helix in the conventional tape model is quite encumbered [5].…”

Section: Dispersion Relationmentioning

confidence: 99%

“…Today's electronic warfare (EW) systems like electronic counter measure (ECM) and electronic counter counter measure (ECCM) are dependent on wideband helix TWTs for their wideband capability. A wideband TWT universally uses helical slow-wave structure (SWS) as the interaction structure due to its non-resonant behaviour and consequent wide bandwidth potential [1][2][3][4][5][6][7][8][9][10][11][12][13]. The bandwidth and other performance like gain efficiency etc.…”

Section: Introductionmentioning

confidence: 99%

“…Discrete dielectric support rods geometry of the SWS, which usually differ from the wedge shape, causes an inhomogeneous loading of the helix [1][2][3][4][5][6][7]. The metal segments/vanes projecting radially inwards from the metal envelope causes anisotropic loading of the SWS [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

A Simple Analysis of Helical Slow-Wave Structure Loaded by Dielectric Embedded Metal Segments for Wideband Traveling-Wave Tubes

Seshadri¹,

Ghosh²,

Bhansiwal³

et al. 2010

PIER B

Self Cite

View full text Add to dashboard Cite

Abstract-A simple field analysis was developed for helical slowwave structure symmetrically supported by rectangular shaped discrete dielectric support rods partially embedded in the metal segments projecting radially inward from a metal envelope for wideband traveling-wave tubes. The tape helix model was used for the prediction of the dispersion relation and the interaction impedance characteristics. The closed form simplified expressions are obtained by combining the tape model dispersion relation for free-space helix and the dielectric loading factor obtained for the loaded helix in the sheath model. The dispersion characteristics and the interaction impedance characteristics obtained by the present analysis were compared with other more involved analytical method reported in the literature for the similar helical slow-wave structure and found to be in close agreement. The present analytical results were also validated against HFSS simulation with an agreement within 5% for both the characteristics for a wide range of structure parameters. An appropriate choice of the structure parameters (helix thickness, height of the metal segments, material of the dielectric support rods, wedge segments angle and helix pitch) provided the phase velocity varying with frequency corresponding to flat to negative structure dispersion with an appreciable interaction impedance values over a wide frequency band. The present analysis enjoys simplicity and establishes the potential of the proposed helical interaction structure for its employment in wideband traveling-wave tubes.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Dispersion Relationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A Simple Analysis of Helical Slow-Wave Structure Loaded by Dielectric Embedded Metal Segments for Wideband Traveling-Wave Tubes

Seshadri¹,

Ghosh²,

Bhansiwal³

et al. 2010

PIER B

Self Cite

View full text Add to dashboard Cite

show abstract

“…In addition to the dominant T + 1 mode, there are also other modes including T + 0 , T + 2 as well as the corresponding reflected components T − 1 , T − 0 and T − 2 from the open end of the helix. These modes can be studied rigorously by considering the helix as an infinite periodic structure [6,7]. However, the excitation strength of these modes cannot be obtained in this manner.…”

Section: Introductionmentioning

confidence: 99%

Improved Current Decomposition in Helical Antennas Using the Esprit Algorithm

Li¹,

Líu²

2010

PIER

View full text Add to dashboard Cite

Abstract-We apply the ESPRIT algorithm to decompose the currents on a helical antenna into different traveling wave modes. The strengths, phase velocities and decay constants of the various modes are extracted across frequencies. Their contributions to the antenna performance including gain, polarization and time-domain radiated pulse shape are investigated. Our results show that the T + 0 mode is a dominant contributor to the helix gain at the low end of the frequency band while the T + 1 mode contributes significantly to the gain at higher frequencies. It is also found that the reflected current modes from the open end reduce the circular polarization purity of the helix. Lastly, it is observed that the T + 1 and T + 0 modes contribute constructively to a low-dispersion pulse from the antenna.

show abstract

Reflection and transmission of electromagnetic slow-waves by a uniformly moving dielectric slab

Xia

Dong

2010

Chin. Sci. Bull.

View full text Add to dashboard Cite

The reflection and transmission problem of an electromagnetic slow-wave by a uniformly moving dielectric slab was investigated theoretically. The relationships among the field vectors of the incident, reflected and transmitted waves, and the reflection and transmission coefficients were derived based on the electromagnetic theory and the principle of special relativity. The numerical analysis shows that at a small mechanical velocity the reflection coefficient of the electromagnetic slow-wave can be close to unit by choosing an appropriate period and mode-order; this is obviously different from that of a fast wave. The results are significant for research on electromagnetics and electrodynamics, and may have applicability to other fields. electromagnetic slow-wave, moving dielectric slab, reflection, transmission Citation: Xia D, Dong T L. Reflection and transmission of electromagnetic slow-waves by a uniformly moving dielectric slab.Research on the problem of the scattering of electromagnetic waves by moving objects and media has a long history, and is interesting from a practical and theoretical point of view. Early in the 1960s, Yeh [1-3] in his series of papers discussed a number of problems such as the reflection and transmission of plane electromagnetic waves by a moving dielectric medium, a moving dielectric slab, and a moving plasma medium. Later, Kong and Cheng [4] studied the problems of reflection and refraction of electromagnetic waves by a moving uniaxially anisotropic slab with an arbitrary plane of incidence. Huang et al. [5,6] analyzed the problems of reflection and transmission of electromagnetic waves by a dielectric medium and the reflection problem of plane electromagnetic waves from the surface of a perfect conductor moving in an arbitrary direction. Recently, Censor not only investigated non-relativistic or quasi-relativistic scattering by moving media and objects [7-10], but also developed the pertinent low-frequency scattering problems involving objects moving with arbitrary constant velocities in free space [11]. Moreover, the scattering of an electro-*Corresponding author (magnetic pulse by a perfectly conducting half-plane moving in a free space has also been of interest [12]. In these works, various interesting features were observed concerning the variation in the reflection and transmission coefficients, the angles of reflection and transmission, and the frequencies of the reflected and transmitted waves as functions of the velocity of the moving object. However, in almost all of these problems of electromagnetic wave scattering, the incident wave was a universal fast-wave. Currently, little theoretical work is being done with respect to incident slow-waves. An electromagnetic slow-wave is usually generated by periodic slow-wave structures, such as helix [13,14], grating [15,16] and photonic crystal [17]. Because of the unique characteristics of slow-wave structures [18], the scattering characteristics of incident slow-waves may also be unique and significant in relevant applications...

show abstract

Space-Harmonic Effects in Helical Slow-Wave Structure --- an Equivalent Circuit Analysis

Abstract: The analysis of a lossless helical slow-wave structure (SWS) using equivalent circuit approach, reported elsewhere, had been carried out for the fundamental mode only. This is essentially used to predict the transmission line parameters. Moreover, in the analysis the

Cited by 7 publications

References 12 publications

A Simple Analysis of Helical Slow-Wave Structure Loaded by Dielectric Embedded Metal Segments for Wideband Traveling-Wave Tubes

A Simple Analysis of Helical Slow-Wave Structure Loaded by Dielectric Embedded Metal Segments for Wideband Traveling-Wave Tubes

Improved Current Decomposition in Helical Antennas Using the Esprit Algorithm

Reflection and transmission of electromagnetic slow-waves by a uniformly moving dielectric slab

Contact Info

Product

Resources

About