Electromagnetic Waveguide Research Articles

Robust and Tunable One-Way Magnetic Surface Plasmon Waveguide: An Experimental Demonstration

We have demonstrated experimentally a one-way magnetic surface plasmon (MSP) electromagnetic (EM) waveguide in the microwave range based on the magnetic photonic crystals (MPCs). The waveguide exhibits asymmetric transmission of EM waves in the frequency range near the MSP resonance for an MPC, such that a significant one-way propagation can be observed in the channel between the two MPC slabs, each in an external static magnetic field (ESMF) of opposite directions. The one-way waveguide is not only immune to interstitial metal defects but also robust against the disorder of rod position. Furthermore, its working frequency can be flexibly tuned by an ESMF, which makes it more favorable for the design of EM devices. The physics is related to the broken time-reversal symmetry of the MSP band states and the excitation of a giant circulation of the energy flow, similar to the case in the quantized Hall effect.

Calculation of the frequency characteristics of the electromagnetic radiation of waveguide-horn antennas

A method for calculation of the frequency characteristics of the electromagnetic radiation of waveguide-horn antennas is proposed. The method is based of frequency expansions of the field of the electromagnetic radiation of the antenna excited by auxiliary finite pulses. This radiation is calculated with the use of the method of nonstationary waveguide equations and the concept of a virtual electromagnetic waveguide. Examples of calculation of the amplitude-phase characteristics of the circuit and radiation patterns at fixed frequencies are presented. It is shown that a high accuracy of determination of frequency characteristics is attainable in rather wide frequency band.

Calculation of the radiation of a waveguide-horn antenna excited by short electromagnetic pulses

A method for the numerical calculation of the electromagnetic field radiated into free space by a waveguide-horn antenna excited by short ultra-wideband electromagnetic pulses (UWB EMPs) is described. Calculations are based on the method of nonstationary waveguide equations, which was proposed earlier, and the concept of a virtual electromagnetic waveguide. It is shown that the proposed approach allows calculation of the “forward radiation field” with control of the error in the obtained results and ensures a high accuracy of calculations.

On the completeness of the system of eigenvectors of electromagnetic waveguides

Several statements of the spectral problem in the theory of regular waveguides are considered. The completeness of the system of eigenvectors of these problems, which is a consequence of the earlier established completeness property of a certain system of eigenvectors, is proved.

Self-adaptive fast frequency sweep for the finite element analysis of waveguide modes

[1] This paper presents a self-adaptive frequency sweep technique for the modal analysis of inhomogeneous electromagnetic waveguides over wide frequency bands. It rests on a multipoint order reduction approach for the finite element method and employs an adaptive scheme based on successive bisection to control the error in the propagation constants of the considered modes. The suggested approach is highly accurate and significantly faster than full finite element computations. Numerical examples are presented to validate the new method and to demonstrate the exponential convergence rate of the reduced-order model.

Benefits of on-wafer calibration standards fabricated in membrane technology

Abstract. In this work we compare on-wafer calibration standards fabricated in membrane technology with standards built in conventional thin-film technology. We perform this comparison by investigating the propagation of uncertainties in the geometry and material properties to the broadband electrical properties of the standards. For coplanar waveguides used as line standards the analysis based on Monte Carlo simulations demonstrates an up to tenfold reduction in uncertainty depending on the electromagnetic waveguide property we look at.

Molding reflection from metamaterials based on magnetic surface plasmons

We demonstrate a dramatically molded reflection of an electromagnetic (EM) wave from the magnetic metamaterial (MM) surface occurring near the magnetic surface plasmon (MSP) resonance. It is found that on one side of the source the reflected field nearly cancels the incoming field, giving rise to a shadowy region near the MM surface, while on the other side the reflected field considerably enhances the incoming field, resulting in a brightened region. Our analysis indicates that this effect arises from the coupling of the EM wave to the MSP band states which exhibit giant circulations going only in one direction due to the broken time reversal symmetry in MMs. Possible applications based on this effect are manifested in designing a robust one-way EM waveguide (OEMW), a ${90}^{\ifmmode^\circ\else\textdegree\fi{}}$ beam bender, and a beam splitter, which are shown to work even in deep subwavelength lateral scale ($~\ensuremath{\lambda}/10$), with $\ensuremath{\lambda}$ the wavelength of the propagating EM wave. Furthermore, the dependence of the OEMW on the channel width, the robustness of the OEMW against the defect and disorder, and the tunability of the working frequency by an external magnetic field are also studied.

Modal formation of electromagnetic fields in a geological stratum with loss tangent greater than unity

Recent research into very large, regularly shaped, geological structures has shown that in the 100kHz to 10MHz frequency range electromagnetic waveguide behaviour is observed when the material forming the structure is not too lossy (conductivity σ < 0.0001). While mode formation and modal behaviour in electromagnetic waveguides is very well understood, much of the literature describes high frequency structures for which it can generally be assumed that the loss tangent of the wave guiding medium (tanδ) is very much less than unity. In this case wave attenuation is small and can generally be considered to be insignificant. This is not true for large low frequency waveguides, such as those formed by geological strata, and little seems to have been reported in the literature on the nature of modes in waveguides of this description. The paper takes the form of a parametric study aimed at ascertaining the limitations to modal formation in waveguides, for which tanδ is greater than unity, by revisiting the basic equations describing electromagnetic wave propagation in lossy media. The theoretical predictions are supported by modelling studies on large waveguide strata formed from material layers with dimensions typical of a geological structure such as a coal seam or oil-wet, strata-bound, petroleum reservoir.

Completeness of a system of eigenvectors of quadratic operator sheaf in waveguide theory

The completeness of the system of eigenvectors Hn of a quadratic operator sheaf that occurs in the theory of electromagnetic waveguides is proven. The completeness of another system of eigenvectors of the spectral problem of waveguide theory that was considered in another formulation that was established earlier is used in the proof.

Fundamental behavior of electric field enhancements in the gaps between closely spaced nanostructures

We demonstrate that the electric field enhancement that occurs in a gap between two closely spaced nanostructures, such as metallic nanoparticles, is the result of a transverse electromagnetic waveguide mode. We derive an explicit semianalytic equation for the enhancement as a function of gap size, which we show has a universal qualitative behavior in that it applies irrespective of the material or geometry of the nanostructures and even in the presence of surface plasmons. Examples of perfect electrically conducting and Ag thin-wire antennas and a dimer of Ag spheres are presented and discussed.

Terahertz electromagnetic crystal waveguide fabricated by polymer jetting rapid prototyping

An all-dielectric THz waveguide has been designed, fabricated and characterized. The design is based on a hollow-core electromagnetic crystal waveguide, and the fabrication is implemented via polymer-jetting rapid prototyping. Measurements of the waveguide power loss factor show good agreement with simulation. As an initial example, a waveguide with propagation loss of 0.03 dB/mm at 105 GHz is demonstrated.

Transverse Vibrations of Viscoelastic Bars Subjected to an Asymmetric Temperature Distribution Induced by a Microwave Source

This paper studies the effects of a microwave excitation on the transverse vibrations of viscoelastic bars placed inside unconventional electromagnetic waveguides. Its purpose is to present a general approach that can be applied to analyze and to interpret the physical phenomena risen during the heating process. These phenomena were not predicted either by conventional experiments or by existing theoretical models. To measure the bar transverse deformations, an opening line and a hole have been made respectively on one of the small transverse sides of the waveguides. The comparison between the spectra of the experimental transverse velocities measured with these two waveguides has pointed out some differences. Theoretical and finite element (FE) simulations of the experiments have been firstly applied to figure out the nature of these variations. The analysis is conducted by a parameterized approach that takes into account the effects of the opening line made along the waveguide on both the propagation of the electromagnetic power density and the temperature rise distribution inside the sample. Good agreements between the models and the experimental data are demonstrated. Furthermore, the method has also shown a sudden asymmetric temperature distribution that leads to the generation of new flexural modes. These last modes are specific to the experiment used to apply the microwave induce acoustic technique.

A quasi transverse electromagnetic mode waveguide developed by using metal-patch electromagnetic bandgap structure

To solve the narrow operation-band of the electromagnetic bandgap (EBG) waveguide, a quasi transverse electromagnetic (TEM) mode waveguide using the metal-patch EBG structure as sidewall is proposed in this paper. Theoretical analysis and numerical calculation show that broader bandwidth, better transportation property, and more uniform electric field distribution of the quasi-TEM mode can be reached. Simulation results using Ansoft HFSS indicate that the metal-patch EBG structure can convert TE10 mode into quasi-TEM mode in the central frequency of 14 GHz with a bandwidth of 1.7 GHz and the uniformity of electric field distribution reaches 84.7% in 83.9% cross section area.

ELECTROMAGNETIC MODING IN LOSSY GEOLOGICAL STRATA

Recent research into very large, regularly shaped, geological structures has shown that in the 100kHz to 10MHz frequency range electromagnetic waveguide behaviour is observed when the material forming the structure is not too lossy (conductivity ae < 0:0001). While mode formation and modal behaviour in electromagnetic waveguides is very well understood, much of the literature describes high frequency structures for which it can generally be assumed that the loss tangent of the wave guiding medium (tan-) is very much less than unity. In this case, wave attenuation is small and can generally be considered to be insigniflcant. This is not true for large low frequency waveguides, such as those formed by geological strata, and little seems to have been reported in the literature on the nature of modes in waveguides of this description. The paper takes the form of a parametric study aimed at ascertaining the limitations to modal formation in waveguides, for which tan- is greater than unity, by revisiting the basic equations describing electromagnetic wave propagation in lossy media. The theoretical predictions are supported by modelling studies on large waveguide strata formed from material layers with dimensions typical of a geological structure such as a coal seam or oil-wet, strata-bound, petroleum reservoir.

OS0319 電磁波を用いた金属配管変形検出(OS3-4 電磁気,OS-3 非破壊評価と構造モニタリング2)

Metallic piping in chemical plants has been used for a long term. In order to prevent serious accident, inspection techniques for maintenance are very important. This report presents a new technique to detect deformation of metallic piping using characteristics of electromagnetic wave propagation. In this method, metallic piping is considered as a electromagnetic circular waveguide, then characteristics of electromagnetic wave propagation through the piping under test is measured. Propagation characteristics depend on a shape of circular waveguide, therefore the deformation part in piping under test affects the characteristics as the transfer and reflection parameters (S-parameters). In order to perform the measurements of these characteristics, Vector Network Analyzer (VNA) which is usually used for measurement of electronic circuits is applied to fault detection on metallic piping. Measuring ports on the VNA are connected to both sides of piping, then transfer and reflection characteristics of the piping are measured as S-parameters using the VNA. In order to verify this method, we performed experiments on a metallic circular waveguide with a local deformation as piping under test. As a result, propagation characteristics of electromagnetic wave through the piping indicate the existence of deformation in piping under test.

USING NANOPARTICLES FOR ENHANCING THE FOCUSING HEATING EFFECT OF AN EXTERNAL WAVEGUIDE APPLICATOR FOR ONCOLOGY HYPERTHERMIA: EVALUATION IN MUSCLE AND TUMOR PHANTOMS

A technical challenge in hyperthermia therapy is to locally heat the tumor region up to an appropriate temperature to destroy cancerous cells, without damaging the surrounding healthy tissue. Magnetic fluid hyperthermia (MFH) is a novel, minimally invasive therapy aiming at concentrating heat inside cancerous tissues. This therapy is based on the injection of different superparamagnetic nanoparticles inside the tumor. In our study, superparamagnetic nanoparticles, which we developed and characterized, consisted of iron oxide nanoparticles stabilized with polyethylene glycol. Moreover, a new technique for MFH using a specially designed external electromagnetic waveguide as applicator is presented. Three magnetite concentrations were used for making the tumor phantoms, which were embedded in muscle phantoms. The phantoms were radiated and located at three different distances from the applicator. Furthermore, two volumes of tumor (2.5mL and 5.0mL) were assayed. Heating curves, as a function of time, allowed the establishment of a more appropriate nanoparticle concentration for obtaining the temperature increase suitable for hyperthermia therapy. The results shown in this Received 29 September 2011, Accepted 19 October 2011, Scheduled 1 November 2011 * Corresponding author: Citlalli Jessica Trujillo-Romero (ctrujillo@cinvestav.mx). The technical contribution of the second author to this work was as significant as the first

On the theory of a virtual electromagnetic waveguide with a guide metallic conductor

On the theory of a virtual electromagnetic waveguide with a guide metallic conductor

Calculation of the field distribution of an ultrawideband short electromagnetic pulse in the radiating aperture of an open-ended irregular waveguide

A new approach to the numerical calculation of the field of ultrawideband electromagnetic pulses in the radiating aperture of a horn antenna is studied. The approach is based on application of the concept of virtual electromagnetic waveguide and the method of nonstationary waveguide equations. It is shown that the proposed approach enables the control of the error in the obtained results and ensures a high accuracy of these results.

Magnetically controllable unidirectional electromagnetic waveguiding devices designed with metamaterials

We demonstrate a sharply asymmetric reflection in a geometrically symmetric magnetic metamaterial (MM) system, which originates from the coupling of electromagnetic (EM) wave to magnetic surface plasmon resonance states and the broken time reversal symmetry in MM. Based on this effect, we have designed unidirectional EM waveguide, wave bender, and beam splitter. Our simulations indicate that the designs possess the merits of robustness against strong defect and disorder, controllability with an external magnetic field, in addition to the finite working bandwidth and the high transmission efficiency.

Arbitrary Electromagnetic Conductor Boundaries Using Faraday Rotation in a Grounded Ferrite Slab

The realization of arbitrary perfect electromagnetic conductor boundaries by a grounded ferrite slab using Faraday rotation is proposed. This is the first practical realization of a perfect electromagnetic conductor boundary to the authors' knowledge. The key principle of the grounded ferrite perfect electromagnetic conductor boundary is the combination of Faraday rotation and reflection from the perfect electric conductor of the ground plane. From this combined effect, arbitrary angles between the incident and reflected fields can be obtained at the surface of the slab, so as to achieve arbitrary perfect electromagnetic conductor conditions by superposition with the incident field. An exact electromagnetic analysis of the structure is performed based on the generalized scattering matrix method and an in-depth description of its operation phenomenology is provided. As an illustration, a tunable transverse electromagnetic (TEM) waveguide with grounded ferrite PMC lateral walls is demonstrated experimentally. Due to its flexibility in the control of the polarization of the reflected field, the proposed grounded ferrite perfect electromagnetic conductor may find applications in various types of reflectors and polarization-based radio frequency identifiers.