Showing papers in "Journal of Electromagnetic Waves and Applications in 2005"
TL;DR: In this article, the authors interpreted the PEMC medium in terms of the classical Gibbsian vectors as a bi-isotropic medium with infinite values for its four medium parameters.
Abstract: In differential-form representation, the Maxwell equations are represented by simple differential relations between the electromagnetic two-forms and source three-forms while the electromagnetic medium is defined through a constitutive relation between the two-forms. The simplest of such relations expresses the electromagnetic two-forms as scalar multiples of one another. Because of its strange properties, the corresponding medium has been considered as nonphysical. In this study such a medium is interpreted in terms of the classical Gibbsian vectors as a bi-isotropic medium with infinite values for its four medium parameters. It is shown that the medium is a generalization of both PEC (perfect electric conductor) and PMC (perfect magnetic conductor) media, with similar properties. This is why the medium is labeled as PEMC (perfect electromagnetic conductor). Defining a certain class of duality transformations, PEMC medium can be transformed to PEC or PMC media. As an application, plane-wave reflection fr...
306 citations
TL;DR: In this article, a square slot antenna fed by two orthogonal feedlines is designed for dual polarized applications, which can simultaneously serve most of the modern wireless communication applications that operate at 1.8, 1.9, 2.4, 5.2 and 5.8 GHz.
Abstract: A square slot antenna fed by two orthogonal feedlines is designed for dual polarized applications. The presented antenna has not only a dual operating band, but also a very wide bandwidth. The bandwidth is 91% in the first band and 40% in the second one. It can simultaneously serve most of the modern wireless communication applications that operate at 1.8, 1.9, 2.4, 5.2 and 5.8 GHz and require wideband characteristics. The antenna can also produce circular polarization with wideband characteristics.
66 citations
TL;DR: In this article, the double negative material was applied in some basic applications, including waveguide, rectangular patch antenna and disc patch antenna, and it was shown that the sizes of these equipments can be greatly reduced by using multi-block (which may include both double positive and double negative materials) dielectric materials.
Abstract: In this paper, we apply the Double Negative Material in some basic applications, including waveguide, rectangular patch antenna and disc patch antenna. By analyzing theoretically we find that the sizes of these equipments can be greatly reduced by using multi-block (which may include both double positive and double negative material) dielectric materials. In addition, the sizes of patch antennas are no longer proportional to the working frequency but roughly to the ratio of the thicknesses of dielectric slabs. Still some new modes in both waveguide and patch antennas are found, and by working at the new modes the bandwidth of the patch antenna can be dramatically increased.
42 citations
TL;DR: In this article, the microwave transmission and reflection in a periodic superconductor/dielectric film multilayer structure in the mixed state are theoretically calculated based on the model of vortex dynamics of a type-II superconductuctor in the mix state as well as the transfer matrix method in a stratified medium.
Abstract: Microwave transmission and reflection in a periodic superconductor/dielectric film multilayer structure in the mixed state are theoretically calculated. It is based on the model of vortex dynamics of a type-II superconductor in the mixed state as well as the transfer matrix method in a stratified medium. We have made some numerical analyses in the microwave transmission and reflection as functions of temperature, dielectric thickness, and number of periodicity as well. The results indicate that the temperature-dependent reflection can be enhanced by increasing the number of periodicity. In addition, both microwave reflection and transmission will be reduced if the thickness of dielectric film is increased.
42 citations
Abstract: Electromagnetic material characterization measurements are an important aspect of modern design. Rectangular waveguides are often used in the material characterization process to facilitate measurement since they are readily available and because rectangular samples can be easily machined and placed in the cross-sectional plane of the waveguide for reflection and transmission testing and subsequently analyzed using a simple theory [1, 2]. However, this technique can produce unacceptably large errors for high loss or highly reflecting samples due to a poor signal-to-noise ratio (SNR) for the transmission measurement.In this paper, a partially-filled waveguide method is presented that enhances transmission quality and accuracy in electromagnetic material characterization measurements. The partially-filled waveguide geometry improves transmission but leads to the excitation of higher-order modes. A mode-matching technique is developed here to accommodate the resulting waveguide discontinuity and a Newton roo...
40 citations
TL;DR: In this paper, the intra-channel collision of optical solitons, with Kerr law nonlinearity, is studied by the aid of quasi-particle theory, and the suppression of soliton-soliton interaction, in presence of these perturbation terms, is acheived.
Abstract: The intra-channel collision of optical solitons, with Kerr law nonlinearity, is studied in this paper by the aid of quasi-particle theory. The perturbation terms that are considered in this paper are all of Hamiltonian type. The suppression of soliton-soliton interaction, in presence of these perturbation terms, is acheived. The numerical simulations support the theory.
36 citations
TL;DR: In this paper, the authors considered the case of rectangular and circular shaped tunnels excited by high frequency electromagnetic fields and derived closed form expressions for the modal attenuation rates of the dominant modes.
Abstract: Modal propagation in tunnels within the earth environment is considered for the case of rectangular and circular shaped tunnels excited by high frequency electromagnetic fields. It is shown that when the applied frequency is sufficiently high, simple forms of the modal fields exist for tunnels with rectangular cross section. The dominant modes in a circular tunnel are hybrid balanced modes in the high frequency limit. Closed form expressions for the modal attenuation rates of the dominant modes in rectangular and circular tunnels are derived and assessed against numerical solutions of the modal equations based on constant surface impedance wall assumption. The case of a curved rectangular tunnel is studied using the Airy function representation of the modal fields. Modal propagation constants in curved tunnels for different polarizations are obtained and it is shown that the tunnel curvature can drastically increase the modal attenuation. Numerical results show that the modes having perpendicular electric...
36 citations
TL;DR: In this paper, the Sinc-collocation method is presented for solving Hallen's integral equations, and properties of Sinc functions are first presented, these properties are then utilized to reduce the computation of Hallen integral equations to some linear algebraic equations.
Abstract: The Sinc-collocation method is presented for solving Hallen's integral equations. Properties of Sinc functions are first presented, these properties are then utilized to reduce the computation of Hallen's integral equations to some linear algebraic equations. The method is computationally attractive, and applications are demonstrated through an illustrative example.
31 citations
TL;DR: In this paper, the authors presented a new set of formulas to compute the field distribution near an electrically large conductor modeled by non-uniform rational B-spline (NURBS) surfaces using physical optics (PO) method.
Abstract: This paper presents a new set of formulas to compute the field distribution near an electrically large conductor modeled by non-uniform rational B-spline (NURBS) surfaces using physical optics (PO) method. Stationary phase method is applied to calculate the PO integral on the rational Bezier Surface. Results obtained by these formulas and by traditional PO method using triangle-modeling technique agree well, which show the accuracy and efficiency of this method.
30 citations
TL;DR: In this article, the surface plasmon resonance (SPR) of a single metallic nanoparticle is analyzed and simulated via multi-multipole method for 3D problems.
Abstract: Surface plasmon resonance (SPR) of a single metallic nanoparticle is analyzed and simulated via multi-multipole method for 3D problems. The excitation, at optical frequencies, of the SPR leads to an extremely strong field in the vicinity of the nanoparticle. Numerical results indicate that a red shift of SPR is induced for an ellipsoidal nanoparticle, compared to a spherical one. Two structures of core-shelled spherical nanoparticles are also studied; one is a nanosphere of Ag shell with an oxide core, and the other one is Ag core with an oxide shell (ZrO2 or SiO2). Numerical results illustrate the SPR of these two core-shelled structures are quite different from each other and different from that of a solid one. It suggests that one can manipulate the optical response on demand by tuning the core/shell ratio and the permittivity of shell or core.
30 citations
TL;DR: In this article, the authors analyzed the broadband properties of the sleeve antenna using the Method of Moments (MOMA) method for three frequency bands: the first and third operating bands come from the driven dipole, while the second operating band is due to the height of the SFA and the distance between the driven Dipole and the sleeve.
Abstract: In this paper broadband characteristics of sleeve antenna are analyzed using the Method of Moments. The sleeve antenna's property of three frequency bands is investigated. The first and third operating bands come from the driven dipole, while the second operating band is due to the height of the sleeve and the distance between the driven dipole and the sleeve. Some numerical results are presented and discussed.
TL;DR: In this paper, a microstrip patch antenna array was developed for a C-band airborne Synthetic Aperture Radar (SAR) using a cost effective substrate with low dielectric constant and moderate loss.
Abstract: A microstrip patch antenna array has been developed for a C-band airborne Synthetic Aperture Radar. The antenna operates at 6 GHz with a bandwidth of 168 MHz (SWR<1.5). It is a rectangular patch fed by a probe from a feed network placed behind the ground plane. A cost effective substrate with low dielectric constant and moderate loss is used for the patch and feed network. The antenna has an optimally shaped beam pattern (with a beamwidth of 24°) in the E-plane with the sidelobe suppressed by 15 dB. In the H-plane, a narrow beamwidth of 3° is designed with the sidelobes suppressed by 30 dB. The antenna achieved a gain of 21.2 dBi. A practical method to compensate for the losses in the feed distribution network is introduced.
TL;DR: The multistatic radar proposed in this paper is composed of a transmitter, placed in a high altitude site, at least four receivers distributed in a low altitude area and a central processing station, to increase the probability of detection of targets with very low monostatic RCS.
Abstract: The multistatic radar proposed in this paper is composed of a transmitter, placed in a high altitude site, at least four receivers distributed in a low altitude area and a central processing station. The transmitter emits a FMCW signal in the air which is reflected by the natural environment and the targets inside the radar's coverage area. The line of sight signal and the collected signal scattered from the surrounding objects are collected from each receiver and a processing algorithm is applied to measure range/doppler and separate the moving air vehicles from the stationary targets (clutter). The targets' range/doppler measurements from every receiver are sent to a central processing station where data fusion of the distributed measurements is performed. A list of the existing tracks is maintained, updated and managed, while deghosting is also applied to remove the pseudo-targets generated from geometrical ambiguities. The main goal of this multistatic radar system is to take advantage of the bistatic...
TL;DR: In this article, a new pattern reconfigurable microstrip antenna is presented to demonstrate the capability of beam steering by controlling MEMS switches on/off, and two sets of connection states and four switchable directional quasi-conical beams in different quadrants can be obtained at 8 GHz and the return losses are less than −10 dB.
Abstract: A new pattern reconfigurable microstrip antenna is presented to demonstrate the capability of beam steering by controlling MEMS switches on/off. Simulated and measured results show that two sets of connection states and four switchable directional quasi-conical beams in different quadrants can be obtained at 8 GHz and the return losses are less than –10 dB. One set of connections provides two quasi-conical half power beams in the first and third quadrants of the upper half space. The second set of connections provides two quasi-conical half power beams in the second and fourth quadrants of the upper half space.
TL;DR: This work uses the M-SVMs to classify an ERS-1 SAR multi-frequency survey of Torre de Hercules coast, Spain (December 13, 1992) and provides interesting results with respect to Neural Networks and Fuzzy classifiers.
Abstract: In this paper, we present the application to SAR imagery classification of a novel pattern recognition technique named Multi-class Support Vector Machines (M-SVMs). M-SVMs are a n-ary extension of Support Vector Machines (SVM), introduced by Vapnik within the framework of the Statistical Learning Theory. In this article we use the M-SVMs in order to classify an ERS-1 SAR multi-frequency survey of Torre de Hercules coast, Spain (December 13, 1992). The main objective of this work is to evaluate the classification performances of M-SVMs in comparison with the most frequently employed Neural Networks and Fuzzy classifiers. M-SVMs provided interesting results with respect to Neural Networks and Fuzzy classifiers, having a reliability factor around to 94%.
TL;DR: In this paper, it was shown that it is possible to reduce Luneburg lens size and weight while retaining at least a vestige of its focusing power, which is a natural generalization of Luneberg's canonical Canonical focusing power.
Abstract: The focusing attributes of spherical Luneburg lenses, quite apart from their inherent physical fascination, offer the practical possibility of transforming low-gain feed patterns into equiphase aperture distributions of appreciable size. These latter yield, in their turn, considerable gain amplification for the far-field beams which they radiate. Such benefit is coupled moreover with an option, at least in principle, to scan beams without restriction on angular amplitude and without any gain/definition degradation penalty whatsoever. Attractive features of this sort notwithstanding, both their bulk and weight militate against widespread Luneburg lens application, and most certainly so in a satellite, size- and weight-averse setting. The question thus naturally arises whether it might be possible somehow to reduce Luneburg lens size and weight while retaining at least a vestige of its focusing power.We answer this question affirmatively by offering, as a most natural generalization of Luneburg's canonical ...
TL;DR: In this paper, a dual-polarized frequency-tunable composite left-handed slab (CLS) is proposed, which consists of periodic split-ring resonators (SRRs) along with thin wires.
Abstract: A dual-polarized frequency-tunable composite left-handed slab (CLS) is proposed. The CLS consists of periodic split-ring resonators (SRRs) along with thin wires. Two orthogonal SRR/wire arrays are ...
TL;DR: In this paper, the natural frequencies of probable targets in a large signal-to-noise ratio (SNR) environment are extracted beforehand and stored, and a correlation factor is defined to quantify the similarity between two responses.
Abstract: A newscheme for radar target discrimination is proposed in this paper. The natural frequencies of probable targets in a large signal-to-noise ratio (SNR) environment are extracted beforehand and stored. The response of an unknown target in low SNR environment is reconstructed using the stored natural frequencies of a particular target, and the coincidence of an unknown target and the particular target is checked by comparing the response of an unknown target with the reconstructed response. A correlation factor is defined to quantify the similarity between two responses. This method is applied to wire targets, and the validity of the method is shown using simulation results.
TL;DR: In this paper, the higher-order resonant modes of a metasolenoid were characterized and the dependency of the resonant frequencies on the dimensions of the metasoleod was studied both analytically and numerically.
Abstract: The higher-order resonant modes of a new artificial magnetic particle — metasolenoid — are characterized and the dependency of the resonant frequencies on the dimensions of the metasolenod are studied both analytically and numerically. The study is relevant to the design of new artificial magnetic materials, slow-wave structures, and filters.
TL;DR: In this article, simultaneous measurements of Ku-band attenuation and rain-rate give A 0.1 and R 0.01 as 9.7 dB and 54 mm/hr respectively, unlike the monotonous variation predicted by the ITU-R model.
Abstract: Simultaneous measurements of Ku-band attenuation and rain-rate give A 0.01 and R 0.01 as 9.7 dB and 54 mm/hr respectively, Unlike the monotonous variation predicted by the ITU-R model, breakpoints ...
TL;DR: In this article, the authors summarize and systematize the mathematical tools used in free-space electromagnetic wave scattering problems and present a package of various representations for the scattered wave by moving objects and the associated scattering amplitude.
Abstract: This study attempts to summarize and systematize the mathematical tools used in free-space electromagnetic wave scattering problems. The elements of Relativistic Electrodynamics relevant to the subject are reviewed. Then, various two- and three-dimensional representations for waves scattered by objects at rest are summarized. Finally the two aspects are combined into a package of various representations for the scattered wave by moving objects and the associated scattering amplitude.
TL;DR: In this article, a hybrid finite element-boundary integral (FEM-BI) method was proposed to transform the original chiral target in half space into two chiral targets with the same permittivity and permeability yet conjugate chirality parameters.
Abstract: Electromagnetic scattering from three-dimensional chiral objects above a perfectly electric or magnetic conducting plane (PEC and PMC) is analyzed by the hybrid finite element-boundary integral (FEM-BI) method. The chiral image principle is used to transform the original single chiral target in half space into two chiral targets with the same permittivity and permeability yet conjugate chirality parameters. Numerical examples demonstrate that the FEM-BI method provides a flexible and powerful solution of multiple scattering from inhomogeneous chiral objects. Both near field distribution and radar cross section (RCS) of chiral objects illuminated by plane waves are provided to demonstrate the effectiveness of the hybrid method.
TL;DR: In this paper, a wideband microstrip circular patch antenna with two short circuiting pin loading is proposed for wireless communications over the broad band 1.8-3.0 GHz.
Abstract: A wide-band microstrip circular patch antenna with two short circuiting pin loading is proposed for wireless communications. By using rigorous theory the dominant cavity modes of the patch are studied and it is found that the first four modes of the patch can act as good radiators. Numerical results show that by a proper choice of the pins and feed locations, one can achieve wide band operation with bandwidth as high as 45%. Design examples are presented as wideband patch antennas for wireless communications over the broad band 1.8–3.0 GHz.
TL;DR: In this paper, the human head modeling for the design of handset antennas at 5GHz band is investigated thoroughly, and the effect of the head heterogeneity and shape on the antenna characteristics is investigated.
Abstract: This paper discusses the human head modeling for the design of handset antennas at 5GHz band. The effect of the human head heterogeneity and shape on the antenna characteristics is investigated thoroughly. In addition, an attempt is also made to realize a compact structure for the human head model. For this purpose, the radiation characteristics of a dipole antenna in the presence of several head models are compared. The numerical investigations reveal that the effect of the heterogeneity and shape of the human head model on the antenna characteristics at 5GHz band is marginal. Particularly, reasonable result can be obtained even for a model of rectangular parallelepiped with the dimensions (24 mm thickness × 120 mm × 120 mm). This volume is 96% smaller than the original realistic model.
TL;DR: In this article, the raised cosine (RC) function used in digital communications is proposed as a new interpolation kernel for SAR interferometry, which shows the best result in interpolation accuracy even with much smaller window sizes.
Abstract: Interpolation is necessary for image registration in interferometric synthetic aperture radar (InSAR). In this letter, the raised cosine (RC) function used in digital communications is proposed as a new interpolation kernel for SAR interferometry. Theoretical and simulation results are compared for the new interpolation kernel and the classical ones, and the proposed kernel shows the best result in interpolation accuracy even with much smaller window sizes.
TL;DR: In this paper, a sparse direct solution algorithm for discrete representations of boundary integral operators is proposed, which relies on an expansion of unknown surface currents in a numerically determined basis of functions that are simultaneously localized to small regions on a larger target while also satisfying global boundary conditions.
Abstract: A sparse direct solution algorithm is reported for discrete representations of boundary integral operators. The algorithm relies on an expansion of the unknown surface currents in a numerically determined basis of functions that are simultaneously localized to small regions on a larger target while also satisfying global boundary conditions. It is shown that the QR factorization of the impedance matrix is sparse in this basis at low to moderate frequencies.
TL;DR: In this article, the Galerkin's method of moments (MoM) with the electric field integral equation (EFIE) applied to the metallic surfaces of the waveguide structure is analyzed.
Abstract: Slotted waveguide array is analyzed using the Galerkin's method of moments (MoM) with the electric field integral equation (EFIE) applied to the metallic surfaces of the waveguide structure. The approach differs from existing methods that utilizes asymptotic method, MoM with the magnetic field integral equation (MFIE), or hybrid methods of MoM and boundary element method. Since no ideal assumptions are made, the analysis and computation are considered to be theoretically and numerically rigorous. The method is verified for its accuracy and applicability through comparisons of its numerical results with existing data. New results for arrays with narrow-wall slots cut at various angles of inclination are obtained and discussed.
TL;DR: In this paper, a new T-shaped microstrip (TSM) feeding technique was proposed to improve the impedance bandwidth of an eccentric dual annular slot antenna (EDASA) based on the parametric study, an optimized prototype was fabricated and tested.
Abstract: A new T-shaped microstrip (TSM) feeding technique is proposed to improve the impedance bandwidth of an eccentric dual annular slot antenna (EDASA). Based on the parametric study, an optimized prototype was fabricated and tested. The obtained results show that the proposed optimized structure can achieve a substantially bandwidth improvement compared to a corresponding straight shape microstrip (SSM) fed EDASA. Moreover, with this design, the radiation performance is also improved in term of crosspolarization level. The proposed structure can find its application in wireless local area networks at 5.8 GHz.
TL;DR: In this article, the sensitivity of the open cavity method and the interferometer method to a small disturbance of permittivity is simulated and compared, and based on the simulation a new approach combining merits of the Open Cavity Method and the Interferometer Method is proposed, and its advantages are described.
Abstract: It is a difficulty problem to measure permittivity of a dielectric material accurately whose permittivity is very close to unit. Open cavity method and interferometer method have been used in the past. In this paper, the sensitivity of these two methods to a small disturbance of permittivity is simulated and compared. Based on the simulation a new approach combining merits of the open cavity method and the interferometer method is proposed, and its advantages are described.
TL;DR: In this article, the optical transmission properties of planar metallic films closely coupled to diffraction gratings were studied and it was shown that the coupling between two optically excited surface plasmon (SP) modes on opposite interfaces of the metal film gives rise to a high transmission feature in the spectral transmittance.
Abstract: We have studied the optical transmission properties of planar metallic films closely coupled to diffraction gratings and we show here that this can give rise to plasmon-enhanced transmission. The coupling between two optically excited surface plasmon (SP) modes on opposite interfaces of the metal film gives rise to a high-transmission feature in the spectral transmittance. The overall transmission is a result of the coupling between the incident light and the SP modes, as well as waveguide modes in the dielectric spacer between the diffraction grating and the planar metal film. The spectral locations of the transmission peaks agree well with rigorous coupled wave analysis (RCWA) calculations.