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Journal ArticleDOI

Perfectly conducting tape-helix model for guided electromagnetic wave propagation

TL;DR: In this article, the homogeneous boundary value problem arising in the propagation of electromagnetic waves guided by an open tape helix modelled to be of infinitesimal tape thickness and infinite tape-material conductivity is shown to be inherently ill posed.
Abstract: The homogeneous boundary value problem arising in the propagation of electromagnetic waves guided by an open tape helix modelled to be of infinitesimal tape thickness and infinite tape-material conductivity is shown to be inherently ill posed. It is demonstrated how the ill posed problem may be regularised using the mollification method. The regularised boundary value problem is then solved to yield the approximate dispersion equation which takes the form of the solvability condition for an infinite system of linear homogeneous algebraic equations viz., the determinant of the infinite-order coefficient matrix is zero. For the numerical computation of the dispersion characteristic, all the entries of the symmetrically truncated version of the coefficient matrix are estimated by summing an adequate number of the rapidly converging (after regularisation) series for them. The tape-current distribution is estimated from the null-space vector of the truncated coefficient matrix corresponding to a specified root of the dispersion equation. A comparison of the numerical results with those for the anisotropically conducting model (that neglects the component of the tape-current density perpendicular to the winding direction) of the tape helix reveals that the propagation characteristic computed on the basis of the anisotropically conducting model could be substantially in error even for moderately wide tapes.
Citations
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Journal ArticleDOI
TL;DR: In this article, a rectangular tape helix slow-wave structure with infinitesimal thickness and finite width in free space is investigated, and the dispersion properties and the interaction impedance for transverse antisymmetric modes are obtained.
Abstract: A rectangular tape helix slow-wave structure with infinitesimal thickness and finite width in free space is investigated. With the expansion of surface currents in the helix and the applications of the modified Marcatili’s method, as well as average power flow matching method at the boundaries, the dispersion properties and the interaction impedance for transverse antisymmetric modes in a rectangular tape helix immersed in free space are obtained. It is shown that, compared with the results of the simplified sheath model by previous researchers, higher accuracy has been obtained between the calculation results of the present theory and the data obtained from HFSS, and the validity of the present theory is further demonstrated by comparison with experiments. The improved characteristic equations hold scientific and practical significance in the design and performance evaluation of such plane slow-wave structure in the application of compact traveling-wave tubes. The distribution characteristics on the cross section of the longitudinal electric field fundamental component are also discussed based on this theory.

18 citations

Journal ArticleDOI
TL;DR: In this article, the homogeneous boundary value problem in the electromagnetic wave propagation in a dielectric-loaded perfectly conducting tape helix with infinitesimal tape thickness is investigated.
Abstract: The homogeneous boundary value problem existing in the electromagnetic wave propagation in a dielectric-loaded perfectly conducting tape helix with infinitesimal tape thickness is investigated in this study. The ill-posed boundary value problem is regularised using the mollification method. The homogeneous boundary value problem is solved for the dielectric loaded perfectly conducting tape helix taking into account the exact boundary conditions for the perfectly conducting dielectric loaded tape helix. The solved approximate dispersion equation takes the form of the solvability condition for an infinite system of linear homogeneous equations namely, the determinant of the infinite order coefficient matrix is zero. For the numerical computation of the dispersion equation, all the entries of the symmetrically truncated version of the coefficient matrix are estimated by summing an adequate number of the rapidly converging series for them. The tape-current distribution is estimated from the null-space vector of the truncated coefficient matrix corresponding to a specified root of the dispersion equation. The numerical results suggest that the propagation characteristic computed by the anisotropically conducting model (that neglects the component of the tape-current density perpendicular to the winding direction) is only an abstinent approximation to consider for moderately wide tapes.

15 citations

Journal ArticleDOI
TL;DR: In this paper, the large-signal behavior of traveling wave tube amplifier for a linear beam dielectric loaded anisotropic conducting tape helix slow wave structure (SWS) was realized through a swift and reliab...
Abstract: The large-signal behavior of traveling wave tube amplifier for a linear beam dielectric loaded anisotropically conducting tape helix slow wave structure (SWS) is realized through a swift and reliab...

13 citations

Journal ArticleDOI
TL;DR: In this article, a dielectric-loaded tape helix enclosed in a coaxial perfectly conducting cylindrical shell was analyzed for guided electromagnetic wave propagation, and the dispersion equation was solved to yield the solvability condition for an infinite system of linear homogeneous algebraic equations.
Abstract: The practically important case of a dielectric-loaded tape helix enclosed in a coaxial perfectly conducting cylindrical shell is analysed in this paper. The dielectric-loaded tape helix for guided electromagnetic wave propagation considered here has infinitesimal tape thickness and infinite tape-material conductivity. The homogeneous boundary value problem is solved taking into account the exact boundary conditions similar to the case of anisotropically conducting open tape helix model [1, 2]. The boundary value problem is solved to yield the dispersion equation which takes the form of the solvability condition for an infinite system of linear homogeneous algebraic equations viz., the determinant of the infiniteorder coefficient matrix is zero. For the numerical computation of the approximate dispersion characteristic, all the entries of the symmetrically truncated version of the coefficient matrix are estimated by summing an adequate number of the rapidly converging series for them. The tape-current distribution is estimated from the null-space vector of the truncated coefficient matrix corresponding to a specified root of the dispersion equation.

11 citations

Journal ArticleDOI

10 citations


Cites background or methods from "Perfectly conducting tape-helix mod..."

  • ...Finally, radiated electric and magnetic fields are calculated using Equations (15)-(18) by substituting the value of electric vector potential (Q) from Equations (30) and(31)....

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  • ...The total far field radiation is the sum of radiation obtained due to polarization current method and alpha(α) multiplied with radiation due to conducting wires as stated in Equations (16) and (32)....

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  • ...To find the radiated electric field far field radiation characteristics in DLHA, a MATLAB program is written using the Equations (15), (16) and (32)....

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  • ...Substitute electric field components in equation in Equations (19) and (20)....

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  • ...Further, there are many theoretical analysis studied and investigated by different researchers and are presented in the literature.(3-24) In Reference 3, Sensiper investigated the theoretical analysis of free modes that propagate along an infinite helical conductor based on sheath and tape helix model....

    [...]

References
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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

Book
01 Jan 1968
TL;DR: In this article, the convergence of Fourier series on T and convergence of the conjugate function on T was studied, where T is the length of the line of a vector.
Abstract: 1. Fourier series on T 2. The convergence of Fourier series 3. The conjugate function 4. Interpolation of linear operators 5. Lacunary series and quasi-analytic classes 6. Fourier transforms on the line 7. Fourier analysis on locally compact Abelian groups 8. Commutative Banach algebras A. Vector-valued functions B. Probabilistic methods.

2,079 citations

Book
12 Mar 2014
TL;DR: In this article, the authors present a first year graduate text on electromagnetic fields and waves, which serves as a useful reference for researchers and engineers in the areas of microwaves and optoelectronics.
Abstract: This book is a first year graduate text on electromagnetic fields and waves. At the same time it serves as a useful reference for researchers and engineers in the areas of microwaves and optoelectronics. Following the presentation of the physical and mathematical foundations of electromagnetic theory, the book discusses the field analysis of electromagnetic waves confined in material boundaries, or so-called guided waves, electromagnetic waves in open space, scalar diffraction theory and active devices. The theories and methods presented in the book are foundations of wireless engineering, microwave and millimeter wave techniques, optoelectronics and optical fiber transmission.

359 citations

Book
01 Jan 1998
TL;DR: In this paper, the Discrete Fourier Transform and Numerical Computations (DFT) were used for time-frequency analysis in periodic signals and periodical signals.
Abstract: Signals and Systems.- Periodic Signals.- The Discrete Fourier Transform and Numerical Computations.- The Lebesgue Integral.- Spaces.- Convolution and the Fourier Transform of Functions.- Analog Filters.- Distributions.- Convolution and the Fourier Transform of Distributions.- Filters and Distributions.- Sampling and Discrete Filters.- Current Trends: Time-Frequency Analysis.- References.

263 citations

Journal ArticleDOI

207 citations