Transverse Electromagnetic Wave Propagation Research Articles

A Wideband Millimeter-Wave Rotman Lens Multibeam Array Using Substrate Integrated Coaxial Line (SICL) Technology

This article presents a wideband Rotman lens multibeam array implemented with substrate integrated coaxial lines (SICLs) for millimeter-wave (mmW) applications. Unlike other dispersive transmission lines commonly used with printed circuit boards, SICL is a nondispersive planar coaxial line that supports the propagation of transverse electromagnetic waves, thus enabling broadband designs of mmW Rotman lenses. Two types of wideband, compact transition structures consisting of small strips and blind vias were designed to transfer energy between the input–output SICLs and parallel-plate lens cavity. Wideband tapered slot antennas excited by SICLs, with a compact lateral size and wide beamwidths, were introduced as the radiating elements to realize a wide scanning range over a large bandwidth. For a proof-of-concept demonstration, a multibeam array prototype that includes seven beam ports and ten array ports connected to ten antenna elements was designed and fabricated. Experimental results agree well with simulation results and show that the proposed multibeam array has an overall bandwidth of 57% (25–45 GHz) with nearly frequency-invariant beam steering performance within ±45°. The desirable wideband operation in conjunction with the ease of integration with planar circuits and low-cost fabrication make the proposed multibeam array design a promising solution for various mmW applications.

A solver based on pseudo-spectral analytical time-domain method for the two-fluid plasma model

A number of physical processes in laser-plasma interaction can be described with the two-fluid plasma model. We report on a solver for the three-dimensional two-fluid plasma model equations. This solver is particularly suited for simulating the interaction between short laser pulses with plasmas. The fluid solver relies on two-step Lax–Wendroff split with a fourth-order Runge–Kutta scheme, and we use the Pseudo-Spectral Analytical Time-Domain (PSATD) method to solve Maxwell’s curl equations. Overall, this method is only based on finite difference schemes and fast Fourier transforms and does not require any grid staggering. The Pseudo-Spectral Analytical Time-Domain method removes the numerical dispersion for transverse electromagnetic wave propagation in the absence of current that is conventionally observed for other Maxwell solvers. The full algorithm is validated by conservation of energy and momentum when an electromagnetic pulse is launched onto a plasma ramp and by quantitative agreement with wave conversion of p-polarized electromagnetic wave onto a plasma ramp.

Computing Photonic Bandgap from Dispersion Relation for TM Mode Propagation Inside Metamaterial-Based 1D PhC

Aim: Calculation of dispersion profile and photonic bandgap for negative refractive index based onedimensional photonic crystal structure. Objective: Determine mathematically the variation of first and second photonic bandgaps under angular incidence variation for the metamaterial-based 1D PhC structure for both TE and TM mode of propagations. Methods: Two lowermost photonic bandgap widths of metamaterial-based one-dimensional photonic crystal are analytically computed from the dispersion relation under the propagation of transverse electromagnetic wave along the direction of confinement. Three practically realizable double negative index materials are considered for computation of bandgaps, where air-gaps are considered along with the artificially made materials as the composite grating structure. This is a combination of negative positive indices materials, where incident angles are tailored within practical limit to calculate the variation of bandgaps, which may be quasi or complete depending on the material composition and angle of incidence. Results: Results are compared with that obtained for TE mode propagation, and are highly important for design of the all-optical filter with DNG materials.

On the Calculation of the Spectral Bands of One-Dimensional Photonic Crystals

In this work we consider the propagation of transverse electromagnetic waves in one-dimensional photonic crystals consisting of periodic arrays of slabs. On the basis of the Floquet theory we obtain the characteristic function of the periodic medium, which defines the photonic bands of the crystal. The characteristic function is constructed from the monodromy matrices of the slabs. Entries of monodromy matrices are explicitly given as power series of the spectral parameter. The present analysis can be applied not only to homogeneous slabs, but also to slabs with varying refractive indexes. The power series representation of the entries of monodromy matrices leads to an effective numerical method for the calculation of the spectral bands of one-dimensional photonic crystals.

An Effective Permittivity Tensor of Cylindrically Perforated Dielectrics

In the letter, we propose a simple analytical effective permittivity model of perforated dielectrics composed of through-hole cylindrical perforations. As the perforated dielectrics are uniaxial media, the model respects the anisotropic properties of the material and the results are simple engineering formulas for effective permittivities of ordinary and extraordinary wave for polarization corresponding to parallel and perpendicular orientation with respect to the axis of perforations. The model is based on the 2-D Maxwell Garnett approximation of inhomogeneous media valid for circularly shaped perforations. The analytical results obtained for propagation of transverse electromagnetic wave are verified by unit-cell full-wave simulations of triangular perforations lattice, and a very good agreement is obtained.

Physics Structure Analysis of Parallel Waves Concept of Physics Teacher Candidate

The aim of this research was to find a parallel structure concept of wave physics and the factors that influence on the formation of parallel conceptions of physics teacher candidates. The method used qualitative research which types of cross-sectional design. These subjects were five of the third semester of basic physics and six of the fifth semester of wave course students. Data collection techniques used think aloud and written tests. Quantitative data were analysed with descriptive technique-percentage. The data analysis technique for belief and be aware of answers uses an explanatory analysis. Results of the research include: 1) the structure of the concept can be displayed through the illustration of a map containing the theoretical core, supplements the theory and phenomena that occur daily; 2) the trend of parallel conception of wave physics have been identified on the stationary waves, resonance of the sound and the propagation of transverse electromagnetic waves; 3) the influence on the parallel conception that reading textbooks less comprehensive and knowledge is partial understanding as forming the structure of the theory.

Geometrical control of transverse electromagnetic wave propagation in nonuniform microwave superconducting transmission lines

It is well known that photonic structures with subwavelength features can be homogenized and thus be accurately approximated by homogeneous yet spatially dispersive structures. This idea is here applied to nonuniform superconducting transmission lines with subwavelength nonuniformities, i.e. subcentimeter features in the microwave regime. A closed form expression is found for the equivalent characteristic impedance and propagation constant of a uniform transmission line that can accurately model the transverse electromagnetic (TEM) propagation within nonuniform superconducting transmission lines with subwavelength inhomogeneities. It is shown that electromagnetic wave propagation, in particular the group velocity of propagating TEM waves, can be well controlled by introduction of subwavelength (subcentimeter) geometrical variations within the line. This ability is of great importance in design of matching stages. In our numerical examples, quasi-TEM superconducting microstrip lines with a superconductive strip of varying width are considered and the group velocity of the quasi-TEM modes is controlled by duly varying the line width. The obtained results are validated by being compared against the well-known technique of stair-case approximation whereby the considered nonuniform line is sliced into several sections each being small enough to be considered uniform.

Lossy three‐phase transmission line transient analysis by Park approach

PurposeTo provide a unified analytical tool, based on Park transformation, for the theoretical and practical analysis of a lossy three‐phase transmission line.Design/methodology/approachThe results obtained in the study of TEM waves propagation in two‐wire line can be extended to a symmetric m‐wire line by employing the modal analysis. This approach relates the dynamic of m‐wire guided field to the propagation of m modal voltages and currents acting on m single‐wire decoupled transverse electromagnetic (TEM) lines. In the symmetric three‐phase system case, the modal analysis includes, as a particular case for m=3, the symmetric component theory. In previous papers, the authors applied the Park transformation to study the wave propagation of (TEM) three‐phase symmetrical lines. The formulation proposed and tested considers the lossless TEM wave propagation of a three‐phase line without consideration to the dissipations phenomena present in the line itself. Taking into account the obtained results, the extension of the developed approach to the lossy three‐phase transmission line transient analysis is very useful on both theoretical and practical points of view.FindingsThe symmetrical three‐phase line Park model for the lossy transmission line transient analysis, regarded as vector formulation of the line modal analysis, has been presented. The proposed examples highlight how, thanks to the Park model, the dynamic analysis of the three‐phase line in distorted and unsymmetrical systems becomes an integral part of the more general and well‐established power electric system dynamic theory.Originality/valueThe three‐phase transmission line transient analysis presented in this paper emphasizes the conceptual contents, specific to the Park approach. Furthermore, it gives some results very important for the practical analysis of a lossy three‐phase transmission line.

Dispersion relations in relativistic astrophysical outflows

In this work we delineate the physical picture for the propagation of electromagnetic oscillations in a moving plasma. We present calculations devoted to describing the dispersion features of the radiation that propagates within a magnetoactive plasma. Both classical and relativistic treatments have been employed. We have concluded that if the outflow is moving with small velocities, the general motion of the plasma does not affect the propagation of transverse electromagnetic waves. The waves are refracted according to the ordinary refraction law deduced for non-moving magnetoactive plasmas. The global movement does not change the dispersion relations, and the shapes of the corresponding curves remain unaltered. In the relativistic formulation, we have derived the equations that determine the electromagnetic wave spectrum for a moving magnetoactive plasma. In this case, it is found that the flow velocity affects the plasma dispersion properties and is responsible for new dispersion branches: transverse and longitudinal perturbations. The ordinary and extraordinary electromagnetic modes are modified and described by dispersion relations whose points of resonance are also in explicit dependence on the plasma velocity. Furthermore, the relativistic motion causes the split of electromagnetic modes into two independent waves that propagate at different rates. This effect is remarkable for highly relativistic velocities. The results presented in this work may be applied in order to incorporate suitable corrections to the dispersion models, developed to explain the anomalous features of observed lines or continuum radiation, associated with astrophysical relativistic outflows which are present in gamma-ray bursts, blazars, relativistic jets in AGNs (active galactic nuclei), quasars and microquasars.

Magnetoinductive waves in one, two, and three dimensions

The propagation of waves supported by capacitively loaded loops is investigated using a circuit model in which each loop is coupled magnetically to a number of other loops. Since the coupling is due to induced voltages the waves are referred to as magnetoinductive (MI) waves. The mathematical formulations are mostly analytical thanks to long standing previous work on the magnetic and electric fields generated by currents flowing in loops. Retardation is neglected, i.e., dimensions of the structure are assumed to be small relative to the free space wavelength. The dispersion relations, derived in the most general case for a tetragonal three-dimensional structure, exhibit both forward and backward waves within a pass band. It is shown that for reproducing the salient features of the waves it is sufficient to take nearest neighbor coupling into account but coupling between loops further away must also be considered if higher accuracy is required. The investigations include that of resonances, conditions for the existence of traveling waves, tolerances, and streamlines of the Poynting vector. Waveguide components, like bends, power dividers and couplers are considered due to the potential applications of the MI waves as magnetic guides. Generality of the results, their possible implications for transverse electromagnetic wave propagation, previous work on similar waves, including the possibility of phase conjugation, are discussed in a separate section.

Dynamical conductivity of type-I semiconductor superlattices

We calculated longitudinal and transverse macroscopic as well as microscopic dynamical conductivity for a modulation-doped type-I superlattice. Our computed long wavelength macroscopic conductivity significantly differs from Drude conductivity in the low-frequency regime (microwave and infrared radiations). Macroscopic conductivity shows oscillatory behaviour along the direction of growth of the superlattice. Propagation of transverse electromagnetic waves in a superlattice has been studied for all possible values of frequency and wavevector. It is found that microscopic transverse conductivity exhibits poles along both real and imaginary axes of frequency. Depending on the values of wavevector components, along and perpendicular to the direction of the superlattice, both poles can lie on real or imaginary axes of frequency. We also find that there can be more than one penetration depth for a superlattice and one of them decreases with frequency for frequencies below the microwave regime.

Transverse wavevector dependent and frequency dependent dielectric function, magnetic permittivity and generalized conductivity of interaction site fluids: MD calculations for the TIP4P water

The dielectric properties of interaction site models of polar fluids may be investigated in a computer experiment using not only the charge fluctuations but also correlations corresponding to a current of moving charges. This current may be associated with a generalized dynamical polarization or separated into electric and magnetic components. The first approach deals with the dielectric permittivity related to a generalized conductivity, whereas the second leads to the functions describing polarization and magnetization fluctuations separately. The latter functions are only the source for calculating the magnetic susceptibility for a system of interaction sites. The transverse wavevector dependent and frequency dependent dielectric functions and magnetic susceptibility are evaluated for the TIP4P water model over a very wide scale of wavelengths and frequencies using molecular dynamics simulations. The transverse part of the dielectric functions may differ drastically from their longitudinal component. A relationship between the two approaches is discussed and the limiting transition to the static dielectric constant in the infinite-wavelength regime is analysed. The propagation of transverse electromagnetic waves in TIP4P water is considered.

Transverse wavevector dependent and frequency dependent dielectric function, magnetic permittivity and generalized conductivity of interaction site fluids: MD calculations for the TIP4P water

The dielectric properties of interaction site models of polar fluids may be investigated in a computer experiment using not only the charge fluctuations but also correlations corresponding to a current of moving charges. This current may be associated with a generalized dynamical polarization or separated into electric and magnetic components. The first approach deals with the dielectric permittivity related to a generalized conductivity, whereas the second leads to the functions describing polarization and magnetization fluctuations separately. The latter functions are only the source for calculating the magnetic susceptibility for a system of interaction sites. The transverse wavevector dependent and frequency dependent dielectric functions and magnetic susceptibility are evaluated for the TIP4P water model over a very wide scale of wavelengths and frequencies using molecular dynamics simulations. The transverse part of the dielectric functions may differ drastically from their longitudinal component. A relationship between the two approaches is discussed and the limiting transition to the static dielectric constant in the infinite-wavelength regime is analysed. The propagation of transverse electromagnetic waves in TIP4P water is considered.

The response of a layered electron gas to a transverse electromagnetic field

The propagation of transverse electromagnetic waves in a layered electron gas is studied from the point of view of the electromagnetic penetration depth. It is found that transverse in-plane plasmons can be observed in systems consisting of two layers of charge carriers per unit cell for special values of wave vector and frequency, determined by the intrinsic parameters of the set-up like the Fermi velocity and the length scales of the unit cell. The internal degrees of freedom in the two layers per unit cell as compared to one layer per unit cell make possible this acoustic-like transverse plasmon. Above the cut-off frequency transverse electromagnetic waves are attenuated as they propagate in the layered electron gas. The layered gas furthermore behaves like a three-dimensional free-electron gas when the layers are close, having the same penetration depth dependence on frequency and the electron relaxation time. In the opposite limit of remote layers the penetration depth is found to be almost independent of these parameters.

Role of optical properties of materials in bremsstrahlung and inverse photoemission

In the course of inverse photoemission and bremsstrahlung investigation in several cases a maximum of radiation has been observed at the photon energy corresponding to that of volume plasmons of the material. Some authors connect this maximum to the plasmon radiative decay. In the present work it is shown, that in the photon energy range corresponding to the plasmon energy some features due to peculiarities of transverse electromagnetic wave propagation in the vicinity of the surface or in a thin film may appear in the radiation spectral distribution. Characteristics of this optical resonance in a massive sample and in a thin film differ significantly. Model calculation results are in agreement with experimental data for Ag and Al massive samples as well for Ag layers on W(110) as Al layers on Nb(110).

Relaxation simulation of transverse electromagnetic wave propagation in coupled transmission lines

An efficient method for computing the transient response of an n-conductor coupled transmission line system that supports transverse electromagnetic waves propagating at different velocities is presented. The method consists of iterative generations of travelling voltage waveforms by the method of characteristics and the waveform relaxation technique. It is shown that the spatial and temporal variations of conductor voltages and currents can be derived from the linear combinations of traveling waves and initial potential and current distributions. Closed-form analytical solutions and experimental data are given to substantiate the accuracy and efficiency of the relaxation technique. >

Propagation of transverse electromagnetic waves with gravitational perturbations in an isotropic universe

The combined behavior of gravitational and electromagnetic perturbations in the radiation-dominated plasma of an isotropic universe is considered. It is shown that transverse electromagnetic waves and vector and tensor gravitational perturbations are independent of one another. The propagation of transverse electromagnetic waves during the lepton and radiation-dominated phases is determined. It is shown that the gravitational perturbations help to excite longitudinal electromagnetic fields in the radiation-dominated plasma.

Dispersion characteristics of 'warm' and 'hot' plasmas

view Abstract Citations (1) References (4) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Dispersion characteristics of 'warm' and 'hot' plasmas Buneman, O. Abstract The range of applicability of the approximate dispersion formula for a warm plasma presented by Ginzburg (1970) and corresponding to the warm (nonrelativistic) plasma limit of an exact fully relativistic dispersion formula for an isotropic hot plasma derived by Buneman (1958) is discussed. It is pointed out that the warm plasma dispersion approximation cannot be used to deduce instabilities or resonances in the range of small phase velocities, nor does it satisfy the Kramers-Kronig relations, while the exact formula does, and can also be easily converted to the cold plasma relativistic dispersion formula. Due to the fact that the exact formula cannot be made explicit for the plasma frequency as a function of the wave number only, nor vice versa, it is recommended that practical calculations of the propagation of transverse electromagnetic waves start with the approximation and estimate relativistic effects by iteration with the exact formula. Publication: The Astrophysical Journal Pub Date: January 1980 DOI: 10.1086/157666 Bibcode: 1980ApJ...235..616B Keywords: High Temperature Plasmas; Plasma Diagnostics; Plasma Diffusion; Relativistic Plasmas; Electromagnetic Radiation; Isotropic Media; Plasma Temperature; Transverse Waves; Plasma Physics full text sources ADS |

Wave Propagation in Negative Differential Conductivity Media: n-Ge

A study has been made of transverse electromagnetic wave propagation in the negative differential resistance medium provided by suitably oriented n-type germanium at 77°K. The wave frequency is cho...

Exact solutions for transverse electromagnetic wave propagation in a cylindrically stratified axially magnetized plasma

AbstractThe equations describing transverse propagation of electromagnetic waves in a cylindrically stratified plasma, in which a static magnetic field is imposed parallel to the axis of cylindrical symmetry, are examined. A systematic method developed previously for isotropic media, Heading (3), Westcott (6) is adapted to yield generalized proffles relating to the plasma properties. These proffles are capable of producing exact solutions for the field distribution in terms of standard transcendental functions. Previously known proffles appear as special cases of the analysis.