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1 edition of Periodic and log periodic coupling of modes of propagation found in the catalog.

Periodic and log periodic coupling of modes of propagation

Jeffrey B. Knorr

Periodic and log periodic coupling of modes of propagation

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  • 40 Currently reading

Published by Naval Postgraduate School in Monterey, California .
Written in English

  • Coupled mode theory,
  • Microwave circuits

  • About the Edition

    The report summarizes an investigation of the applicability of the log periodic concept to coupled microwave transmission lines. It is shown that active coupling at a given frequency may be achieved between two lines supporting waves with different phase constants provided they are coupled periodically with a periodicity determined by the difference B(2)-B(1) at that frequency. Since B(2)-B(1) will, in general, vary with frequency, coupling over a broad frequency range requires a variable period. This may be realized by scaling the structure period, thereby giving rise to a log periodic mode coupler. This technique appears to hold promise for achieving the same wideband performance that has been attained with log periodic radiators. (Author)

    Edition Notes

    Statementby Jeffrey B. Knorr
    ContributionsNaval Postgraduate School (U.S.)
    The Physical Object
    Pagination27 p. :
    Number of Pages27
    ID Numbers
    Open LibraryOL25480984M

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Periodic and log periodic coupling of modes of propagation by Jeffrey B. Knorr Download PDF EPUB FB2

Author(s) key words: Coupled mode theory, periodic coupling, log periodic coupling Includes bibliographical references (p. 17) Technical report; The report summarizes an investigation of the applicability of the log periodic concept to coupled microwave transmission :   Journal of Sound and Vibration () 40(1), WAVE PROPAGATION AND NATURAL MODES IN PERIODIC SYSTEMS: II.

MULTI-COUPLED SYSTEMS, WITH AND WITHOUT DAMPING D. MEAD Department of Aeronatttics and Astronautics, University Periodic and log periodic coupling of modes of propagation book Southampton, Southampton S09 5NH, England (Received 8 July ) Free waves can propagate through periodic Cited by:   Journal of Sound and Vibration () 40(1), WAVE PROPAGATION SYSTEMS: I.

AND NATURAL MODES IN PERIODIC MONO-COUPLED SYSTEMS D. MEAD Department of Aeronautics and Astronautics, University of Southampton, ~Vouthampton S09 5NH, England (Recbived 9 May ) In this paper the relationship is studied between the bounding frequencies of the propa- gation zones of mono-coupled periodic Cited by:   Periodic Structures: Mode-Matching Approach and Applications in Electromagnetic Engineering presents the scattering and guiding characteristics of periodic structures using the mode-matching approach and their applications in electromagnetic engineering.

The book is structured so that the first three chapters provide an introduction and prepare. The wave propagation in a periodic elastic-piezoelectric axial-bending coupled beam is investigated in this paper by considering the mechanical-electrical coupling behavior.

Mutual coupling between log-periodic antennas. None. A Novel Printed Fractal Log-Periodic Dipole Antenna. This paper presents the research on a novel miniaturized printed log-periodic antenna with fractal tree structure for operation in a broadband of GHz- 2GHz.

A group of methods is presented for the high frequency dispersive modeling of elastic wave propagation in periodic media. The methods fall within the framework of the multiscale assumed strain.

On the Computation of the Dispersion Diagram of Symmetric One-Dimensionally Periodic Structures. played by the higher-order mode coupling when different onset of the multi-mode propagation.

A brief review of recent advances in the field of wave propagation in periodic structures is made. The review focuses on the application of, the method of multiple scales to a class of problems in closed- and open-acoustic and electromagnetic. waveguides. In addition, our experimental system opens enticing perspectives to study wave propagation, to reveal analogies with solid state physics, and, more generally, to uncover new phenomena.

Hydroelastic waves could be used to systematically probe the physics of 2D periodic media, as well as to design macroscopic topological materials. Book. Full-text available from information on the coupling strengths and mode propagation constants. The phase shift and attenuation of the fundamental mode caused by a spatially periodic.

Wangler, T. () Periodic Accelerating Structures, in Principles RF Linear Accelerators, Wiley-VCH Verlag GmbH, Weinheim, Germany.

doi: /ch3 Author Information Los Alamos National Laboratory, Los Alamos, New Mexico. Helmholtz resonator is often used to reduce noise in a narrow frequency range.

To obtain a broader noise attenuation band, combing several resonators is a possible way. This paper presents a theoretical study of sound propagation in a one-dimensional duct with identical side-branch resonators mounted periodically.

The coupling angle may create in particular wide attenuation zones due to wave mode conversion. In this paper, a parametric analysis is proposed to highlight its influence on the vibration levels.

Log-periodic dipole antenna with low cross-polarization. In this work, log-periodic antennas with improved cross-polarization level were studied. It was found that some modifications of the traditional design lead to an essential improvement of the co-to-cross polarization ratio up to 40 dB.

Spatial Modulation of Repeated Vibration Modes in Rotationally Periodic Structures M. Kim, M. Kim A General Theory of Harmonic Wave Propagation in Linear Periodic Systems with Multiple Coupling,” Orris, R.

M., and. Petyt, M.,“ A Finite Element Study of Harmonic Wave Propagation in Periodic Structures,” J. Sound. In this paper we investigate the coupling of flexural and longitudinal wave motions in a waveguide with structural side branches attached at regular intervals. The analysis is based on periodic str.

A Log-periodic antenna is that whose impedance is a logarithamically periodic function of frequency. Frequency range. The frequency range, in which the log-periodic antennas operate is around 30 MHz to 3GHz which belong to the VHF and UHF bands. Construction & Working of Log-periodic Antenna.

The construction and operation of a log-periodic. A companion paper [J.– ] has examined the phenomena of flexural-longitudinal wave coupling in a practically undamped and semi-infinite periodic waveguide with structural side-branches. The effect of structural damping on wave coupling in such a waveguide is examined in the first part of the present paper, and the damping-dependent decrease in wave coupling.

It is well known [5] that for frequencies near the gap the propagation is dominated by Bragg-coupling between the forward and backward modes.

In this letter we apply the coupled-mode formalism to describe the propagation characteristics of a TM mode in the gap region (fig. 4 of I) and compare it to the exact analysis. CiteSeerX - Document Details (Isaac Councill, Lee Giles, Pradeep Teregowda): Abstract — The finite-difference time-domain (FDTD) method is applied for studying plasmonic waveguide formed by silver nanorods at optical frequencies.

The dispersion diagram of periodic structures formed by an infinite number of nanorods is calculated by applying Bloch’s periodic boundary condition therefore. When V is greater than then additional modes satisfy the propagation condition and the fiber supports the propagation of more than one LP mode.

When designing the index profile of a single-mode fiber it is usual to place the V value slightly greater than at. Computer modeling studies indicate that planar dielectric waveguides clad with silicon exhibit a damped periodic oscillation in their attenuation and phase characteristics.

The effect is due to a periodic coupling between the lossy, guided modes in the silicon film and the TE/sub 0/ mode of the dielectric waveguide. Experimental confirmation of the periodic coupling for a wavelength of The objective of this work is to provide an accurate model of the lateral resonance modes in 1–3 piezoelectric composite materials.

These materials are widely used in ultrasonic transducers and the lowest lateral mode frequency gives the upper limit for the usable transducer bandwidth. Considering the propagation of purely transverse waves in a 2-D periodic medium of infinite thickness, two.

Abstract. We consider here the propagation of intense light in a periodic structure. The models that we discuss are one-dimensional; this means that only a sin­gle spatial direction, that in which the light propagates, is relevant, and that the refractive index only depends on this spatial coordinate.

Closed solutions of wave propagation in finite–periodic strings 8 February | Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences, Vol.No. The examples considered include periodic/aperiodic spring-mass systems controlled by piezoelectric actuators.

The presented results emphasize the unique potential of the active periodic structures in controlling the wave propagation both in the spectral and spatial domains in an attempt to stop/confine the propagation of undesirable disturbances.

Active localization of wave propagation in elastic beams using periodic placement of piezoelectric actuator/sensor pairs Journal of Applied Physics, Vol.

No. 8 On the positive real property of the impedance matching controller for double. Log periodic formulas. There are several relationships or formulas that describe the characteristics of the log periodic antenna. In particular these can be sued to calculate the lengths and spacings of the elements within the antenna.

Key dimensions for a log periodic dipole array. A novel reconfigurable log periodic patch array has been proposed by inserting switches within the aperture slots coupling the patches to the feed line.

A wideband mode and three narrow band modes of reconfiguration are demonstrated, when groups of patches were selected within the array. The most common analysis method on the periodic waveguide is the coupled mode theory (Yariv in Quantum electronics.

Wiley, New York, ), which is extremely effective to deal with the coupling between different modes. However, the method is cumbersome in mathematics and lack of clearness in giving physical insight.

Mode Coupling Instabilities Induced by a Periodic Coefficient of Friction To predict and minimize squeal propensity in brake systems, numerous. The absence of a rigorous mathematical analysis of the approach, as applied to periodic structures, has resulted in mistreatment of internal forces and misapplication to nonlinear media.

In a previous article (Farzbod and Leamy,“The Treatment of Forces in Bloch Analysis,” J. Sound Vib., (3), pp.

–), we clarified the. This is the first comprehensive volume on nearly periodic structures and mistuned blade vibration. Alok Sinha presents fundamental concepts and state-of-the-art techniques in the analysis of free and forced response of a nearly periodic structure, weaving together his own work (covering thirty-five years of research in this field) with works by other researchers.

Design and analysis of the family of log periodic toothed planer microstrip antenna The shifts in the modes of propagation induced by the gravitational potential are obtained and compared by considering a numerical example.

Published three Books May – : Dr. Aarti Vaish, Program Director. Analogously, Fig. 1c shows a FEM simulation of the mechanical band structure of the infinitely periodic nanobeam.

Mechanical modes at the band edge experience an. A log-periodic antenna (LP), also known as a log-periodic array or log-periodic aerial, is a multi-element, directional antenna designed to operate over a wide band of was invented by John Dunlavy in The most common form of log-periodic antenna is the log-periodic dipole array or LPDA, The LPDA consists of a number of half-wave dipole driven elements of gradually.

LOG-PERIODIC DIPOLE ARRAY OPTIMIZATION Y. Chung and R. Haupt Utah State University Electrical and Computer Engineering Old Main Hill, Logan, UTUSA Abstract-The element lengths, spacings and radii of log-periodic dipole arrays (LPDA) are optimized with a.

By replacing the periodic masses with periodic resonators, the coupling between the rigid mode of the guided beam and the resonator leads to two frequen- cies. The first is a zero frequency rigid mode and the second is a finite frequency mode whose value depends on the properties of the resonator.

Band gaps appear in the frequency spectra of periodic materials and structures. In this work we examine flexural wave propagation in beams and investigate the effects of the various types and properties of periodicity on the frequency band structure, especially the location and width of band gaps.

We use a phenomenological Hamiltonian approach to derive a set of coupled mode equations that describe light propagation in waveguides that are periodically side-coupled to microcavities.

The structure exhibits both Bragg gap and (polariton like) resonator gap in the dispersion relation. for: m=0,\pm 1, \pm 2, For m=0, this reduces to Snell’s law, as \beta_{m\ne0}, if the difference in path lengths equals an integer number of wavelengths in vacuum, then there is constructive interference and a beam of order m is diffracted by angle \beta_{m}.Note that there need not be equal numbers of positive and negative m-orders.A transversal mode with zero group velocity and non-zero phase velocity that can exist in chains of silver nano-spheres in the optical frequency range was theoretically studied.

It is shown that the external source radiating a narrow-band non-monochromatic signal can excite in the chain a mixture of standing and slowly travelling waves. The standing wave component (named as resonator mode) is.