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Extraordinary optical transmission of light or electromagnetic waves through metal plates periodically perforated with subwavelength holes has been exhaustively analyzed in the last ten years. The study of this phenomenon has attracted the attention of many scientists working in the fields of optics and condensed matter physics. This confluence of scientists has given rise to different theories, some of them controversial. The first theoretical explanation was based on the excitation of surface plasmons along the metal-air interfaces. However, since periodically perforated dielectric (and perfect conductor) slabs also exhibit extraordinary transmission, diffraction by a periodic array of scatterers was later considered as the underlying physical phenomenon. From a microwave engineering point of view, periodic structures exhibiting extraordinary optical transmission are very closely related to frequency-selective surfaces. In this paper, we use simple concepts from the theory of frequency-selective surfaces, waveguides, and transmission lines to explain extraordinary transmission for both thin and thick periodically perforated perfect conductor screens. It will be shown that a simple transmission-line equivalent circuit satisfactorily accounts for extraordinary transmission, explaining all of the details of the observed transmission spectra, and easily gives predictions on many features of the phenomenon. Although the equivalent circuit is developed for perfect conductor screens, its extension to dielectric perforated slabs and/or penetrable conductors at optical frequencies is almost straightforward. Our circuit model also predicts extraordinary transmission in nonperiodic systems for which this phenomenon has not yet been reported. Index Terms--Extraordinary transmission, frequency-selective surfaces (FSSs), surface plasmon polaritons.

The finite-element method (FEM) enables the use of 'adapted' meshes. The simultaneous combination of h (local variations in element size) and p (local variations in the polynomial order of approximation) refinements, i.e., hp-adaptivity, is the most powerful and flexible type of adaptivity. In this paper, two versions of a fully automatic hp-adaptive FEM for electromagnetics are presented. The first version is based on minimizing the energy-norm of the error. The second, namely the goal oriented strategy, is based on minimizing the error of a given (user-prescribed) quantity of interest. The adaptive strategy delivers exponential convergence rates for the error, even in the presence of singularities. The hp adaptivity is presented in the context of 2-D analysis of H-plane rectangular waveguide discontinuities. Stabilized variational formulations and H(curl) FEM discretizations in terms of quadrilaterals of variable order of approximation supporting anisotropy and hanging nodes are used. Comparison of energy-norm and goal-oriented hp-adaptive strategies in the context of waveguiding problems is provided. Specifically, the scattering parameters of the discontinuity are used as goal. Index Terms--Finite-element methods (FEMs), rectangular waveguides, waveguide discontinuities.

This paper provides extensive dosimetry data for in vitro experiments regarding the biological effects of millimeter waves. Two particular frequency ranges have been considered, which are: 1) the 57-64-GHz frequency range dedicated to near-future applications in high-speed wireless communication systems and 2) the discrete frequencies used in millimeter-wave therapy, namely, 42.25, 53.57, and 61.22 GHz. The dielectric properties of keratinocyte cells and culture media were determined using permittivity data of free water and Maxwell's mixture equation. The local specific absorption rate (SAR) distribution within the cell monolayer located in a standard tissue culture plate was computed using the finite-element method and the finite-integration technique. The averaged near-surface SAR for the cell monolayer was determined using both numerical electric-field-based and experimental temperature-based approaches. The SAR was computed taking into account physiological variations of the water content in the keratinocyte cells, as well as variations in the cell monolayer thickness. Experimental and computational results are shown to be in very good agreement. Index Terms--Biological effects of electromagnetic (EM) radiation, finite-element method (FEM), infrared radiometry, specific absorption rate (SAR).

In this study, a novel ten-port waveguide microwave sensor is designed, implemented, calibrated and tested in order to obtain the reflection coefficient magnitude and phase. This reflectometer is based on the well known six-port structure but the number of detectors has been increased to eight in order to improve the sampling procedure of the standing wave present within the waveguide. In addition, a learning method based on neural networks' usage has been implemented for autonomous calibration from the data collected by a vector network analyzer. An automated procedure consisting of a moving sample within a multimode cavity has enabled different reflection coefficients to be obtained. Neural networks have been employed in order to learn the relationship between the actual reflection parameter and the acquired signals from eight power detectors. This novel device has been calibrated with a neural architecture based on radial basis functions and the error of device measurements has been analyzed. This new design and the incorporated neural network calibration allow one to avoid problems caused by fault or nonlinearity of the detectors, and to get robustness, flexibility and adaptability characteristics for the presented device. Index Terms--Autonomous calibration, neural networks, scattering parameters, six-port, ten-port microwave reflectometer.

A unified approach for determining the lossy resonance (hot-spot) conditions in a lossy stratified biological tissue model is proposed. These conditions may lead to a significant enhancement of local electromagnetic power deposition in a single layer as compared to the power dissipated in the background. Rigorous analysis of electromagnetic wave power absorption in a planar stratified tissue model renders a closed-form characterization of six possible asymptotic cases and the associated conditions and bounds on the optimal absorption in the particular layer as a function of its normalized thickness and parameters of the surrounding layers. It is shown that, even very thin and low attenuating layers (sites) of biological tissue, are capable of dissipating a very substantial amount of the incident power, subject to specific lossy resonance conditions. From a dosimetric point of view, the results obtained allow for prediction of naturally occurring spatial resonances in biological tissues on both macroscopic and microscopic scales. On the other hand, they also provide an effective mean for design and synthesis of optimally absorbing materials and tissues in therapeutic applications. Index Terms--Electromagnetic dosimetry, lossy biological tissues, resonant absorption.

We propose a generalized S-parameter analysis for transmission lines (TLs) with linear/nonlinear load terminations subject to arbitrary plane-wave and port excitations. S-parameters are prevalently used to model TLs such as cable bundles and interconnects on printed circuit boards (PCBs) subject to port excitations. The conventional S-parameter approach is well suited to characterize interactions among ports. However, nontraditional port excitations associated with plane-wave coupling to physical ports at TL terminals lead to forced, as well as propagating, modal waves, necessitating a modification of the standard S-parameter characterization. In this paper, we consider external plane-wave excitations, as well as port (internal) sources, and propose a hybrid S-parameter matrix for characterization of the associated microwave network and systems. A key aspect of the approach is to treat the forced waves at the ports as constant voltage sources and induced propagating modal waves as additional entries (hybrid S-parameters) in the S-parameter matrix. The resulting hybrid S-matrix and voltage sources can be subsequently exported to any circuit solver such as HSPICE and Agilent's Advanced Design System for the analysis of combined linear and nonlinear circuit terminations at ports. The proposed method is particularly suited for susceptibility analysis of cable bundles and PCBs for electromagnetic interference evaluations. It also exploits numerical techniques for structural and circuit domain characterization and allows for circuit design optimization without a need to perform any further computational electromagnetic analysis. Index Terms--Distal simulation, electromagnetic compatibility (EMC), electromagnetic coupling, electromagnetic fields, electromagnetic interference (EMI), multiconductor transmission lines, port analysis, printed circuit board (PCB), scattering matrix, scattering parameters, S-parameters, transmission lines (TLs), transmission line theory. Digital Object Identifier 10.1109/TMTT.2007.895642

Vector fitting is a robust macromodeling tool for rational approximation of spectral data obtained by full-wave electromagnetic simulators or high-frequency measurements. The technique iteratively calculates a suitable set of poles, and solves the residues of the transfer function in a two-step procedure. If poles with a higher order multiplicity occur during the pole-identification step, numerical problems and inaccuracies can result, especially if the normal equations are solved. This problem is illustrated on an RLC filter, and a generalization of the basis functions is proposed to resolve the issue. Index Terms--Macromodeling, rational approximation, vector fitting.

A modal analysis based on the coupled mode method is performed for the resolution of partially filled waveguides with a general bianisotropic medium. The calculation of the generalized telegraphist's equations can be made by using two different strategies: direct and indirect formulations. In this paper, the indirect formulation of the method is extended to bianisotropic materials and exposed in detail. The convergence of both formulations is compared and it is demonstrated that the indirect formulation converges much faster than the direct formulation, which means that fewer modes are required for a given precision. Results of some particular cases of the constitutive relationships, like dielectric, magnetic, ferrites, and omega materials are shown and compared with the bibliography or commercial electromagnetic simulators. Good agreement is found, which demonstrates the validity and reliability of the method. Index Terms--Coupled mode analysis, nonhomogeneous media, scattering matrices, waveguide discontinuities.

This paper describes a technique for reconstructing one-dimensional stratified permittivity profiles. The proposed technique is based on the inversion of the measured frequency-domain reflection coefficient of the profile into a virtual time domain. The inversion of the reflection coefficient is based on the super-resolution technique root multiple-signal classification. The advantage of using this technique is its ability to remove the sidelobe effect caused by the limited measurement bandwidth. Measurements using different materials have been carried out to validate the quality of the proposed technique. Index Terms--Electromagnetic scattering, inverse problems, microwave imaging, permittivity, super resolution.

A modal analysis of transverse electromagnetic (TEM) mode in a circular-rectangular coaxial waveguide is presented in this paper. The analysis is based on the modal-expansion technique. Analytic expressions for the characteristic impedance and attenuation coefficient are derived from the solution of the TEM mode. The calculated results are compared with those of the finite-element method, as well as published data. Excellent agreement is observed. Index Terms - Coaxial waveguides, modal analysis, TEM mode.

An analytic solution of electromagnetic-wave propagation in a rectangular chirowaveguide is represented in this paper in terms of spectral-domain dyadic Green's functions (DGF's) in a general form. The method used here is a combination of a wavefield decomposition method and DGF eigenfunction expansion technique. This DGF decomposition method avoids having to use the modified and normalized vector wave functions, which are found difficult to satisfy the boundary conditions of chirowaveguides in which the reconciliation of Dirichlet and Neumann conditions is impossible. On the other hand, this method can be generalized to chirowaveguide of arbitrary cross section and is found reducible to a nonchiral case. It is observed that in a similar fashion to the conventional rectangular waveguide, the duality between the electric and magnetic types of DGF's in the rectangular chirowaveguide does not exist. To show the reducibility of the generalized DGF's for bi-isotropic media, we summarized the procedure of utilizing the formulas and proved in detail that the form of the DGF's can be reduced to that for chiral media and achiral (isotropic) media. Exactly the same DGF's are obtainable for the isotropic media by reducing the general formulas. In Part II of this paper, a practical application of the DGF's will be presented. The electric and magnetic fields in the rectangular chirowaveguide due to a point dipole excitation oriented in the [Mathematical Expression Omitted]-direction will be derived. The detailed numerical analysis will include the novel features of the dispersion relations, the effects of chirality on the novel features of the rectangular chirowaveguides, some newly discovered features, and vector field plots and contour plots of higher order modes of electric and magnetic fields. Index Terms - Dyadic Green's functions, electromagnetic-wave theory, microwave propagation, rectangular waveguide, vector wave functions.

A general expression of spectral-domain dyadic Green's function (DGF) in a rectangular chirowaveguide has been represented in Part 1 of this paper. As an application of the theory developed, this paper represents an analytic solution of electromagnetic (EM) wave propagation in the rectangular chirowaveguide. Firstly, the results of EM fields in closed form are obtained by using the DGF decomposition method, which is essentially a combination of the wavefield decomposition method followed by eigenfunction expansion of DGF. Secondly, the novel features of the analytically derived dispersion relations are analyzed and the effects of chirality on the novel features of the dispersion relations and propagation constant are discussed. Distributions of magnetic and electric fields of different order of modes are derived analytically and are then represented in vector field plots and contour plots. Also, the effects of chirality responsible for both plots are discussed. Finally, comparisons between part of the current results and those available in the literature are made. It is observed that this analysis encompasses all the published novel features for a rectangular chirowaveguide, in addition to some newly observed features. The analysis in this part of the paper confirms the applicability of the theoretical analysis given in Part I. Index Terms - Dyadic Green's functions, electromagnetic-wave theory, microwave propagation, rectangular waveguide, vector wave functions.

The propagation characteristics of the slotline first higher order mode are presented in detail in this paper. It is found that the attenuation constants and the radiation band of this first higher order mode are larger than those of the microstrip-line first higher order mode. Dependence of the propagation characteristics on structural parameters and the effect of finite-conductor planes are analyzed. The propagation characteristics of the surface-wave-like modes are also discussed. In order to avoid inadvertent excitation of these surface-wave-like modes in antenna applications, the current and field distributions of the slotline first higher order mode and the surface-wave-like modes are compared and discussed. Excitation of the slotline first higher order mode was conducted by feeding the slotline with a coplanar waveguide and microstrip line. Experimental results show good agreement with our numerical results, and also confirm the existence of the slotline first higher order mode. Index Terms - Higher order mode, leaky-wave antenna, slotline.

There have been several algorithms which extend the finite-difference time-domain (FDTD) solution of Maxwell's equations to nonlinear electromagnetic problems. Relative to other methods, FDTD achieves robustness by directly solving for the fundamental quantifies, electric field E, and magnetic field H in space and time, rather than performing asymptotic analyses or assuming paraxial propagation and nonphysical envelope functions. As a result, the FDTD method is almost completely general and can account for any type of electromagnetic problems. As in linear cases, for a practical simulation, nonlinear FDTD modeling also requires the development of absorbing boundary conditions (ABC's) to effectively absorb the nonlinear electromagnetic waves for open nonlinear structures. In this paper, based on the Berenger's perfectly matched layer (PML), a nonlinear PML (nPML) absorbing scheme is presented and then implemented in the transmission-line matrix (TLM)-based FDTD method. Numerical results are given to demonstrate the effectiveness of the nPML proposed. Index Terms - Absorbing boundary, absorption, FDTD, nonlinear PML, TLM.

TE wave properties of slab dielectric waveguides with nonlinear non-Kerr-like substrate and cladding are presented. The guide can support even- and odd-symmetric modes in asymmetrical substrate and asymmetrical modes in completely symmetrical substrate. Dispersion relations and electric field profiles are illustrated and analytically discussed in detail.

The approximations involved in the effective-index method for analyzing the vector modes of rectangular-core dielectric waveguides are examined in detail. It is shown that the effective-index method does not solve the full vector-wave equation that governs the modes. Instead, it solves the reduced vector-wave equation, which is accurate only for approximately linearly polarized waves. Furthermore, in solving the reduced vector-wave equation, the method of separation of variables is used, which leads to additional errors as the waveguide being analyzed is a mathematically nonseparable structure. To characterize the performance of the effective-index method, asymptotic expressions are derived for the errors in the calculation of propagation constants. Apart from separating the effects of different approximations involved, these expressions show explicitly how the accuracy of the method depends on the mode type, the normalized frequency, the mode orders, the dimensions of the waveguide, and the relative refractive-index differences between the core and the surrounding media. With the help of these expressions, it is demonstrated that more accurate results can be obtained by combining various effective-index solutions.

This paper describes a new method for the analysis of modes propagating in shielded waveguides consisting of many dielectric and perfectly conducting layers of different widths. The eigenvalue problem inherent to the mode determination is formulated subdividing the structure into layered elementary waveguides (EWG's) and matching the fields generated in adjacent EWG's by unknown equivalent sources placed at the interfaces. The special representation of the EWG field, consisting of boundary integrals and mode expansions, leads to a linear matrix eigenvalue problem involving a limited number of variables. Thanks to this peculiarity the method permits to determine many modes in short computing times. The method was implemented in a flexible and fully automatic computer code, whose reliability and efficiency has been confirmed by many tests.

By analyzing the vector and scalar equations for chirowaveguides, two forms of mode orthogonality relations are obtained: the vector formulated orthogonality and the scalar formulated orthogonality. The first one is applicable to the general case of open chiroplasma or chiroferrite waveguides. It is shown that for two parallel-plate isotropic chirowaveguides, these two forms of orthogonality relations differ. Based on mode orthogonality relations, it is shown that in chirowaveguides the polarization of so-called complex modes differs from that of propagating or evanescent modes. The correlation between field components of two complex modes that transfer active power flow in chirowaveguides is obtained.

This paper introduces and analyzes a rectangular resonant structure that provides an alternative to the multimode resonant cavity in applications requiring enhanced field uniformity. The resonant cavity contains four dielectric loading slabs placed along the cavity walls. Its first resonant mode is related to the uniform field distribution supported in a rectangular TEM waveguide. The electromagnetic fields within the cavity are described using a closed-form approach, with approximations taken to account for the presence of two of the loading slabs. Application of the boundary conditions leads to an eigenvalue formulation, which is used to determine resonant frequencies and electromagnetic field distributions within the cavity. Measurements of both resonant frequencies and electric field magnitudes confirm the analysis. This work provides the basis for future analyses and implementation of slab-loaded cavities in both scientific and industrial settings.

Electromagnetic fields in structures composed of inhomogeneous cylindrical layers are analyzed using a propagator matrix approach. The presented formulation is capable of analyzing fully bianisotropic media, where the involved propagator matrix for bianisotropic media is derived in cylindrical coordinates. The applicability of the method is demonstrated by calculating the dispersion characteristics of surface waves as well as fundamental and higher order modes on cylindrical microstrip lines on top of an inhomogeneous bianisotropic substrate.

In this paper a finite element formulation in terms of the magnetic field is presented for the analysis of waveguides with bianisotropic media. Such a formulation can deal with lossy inhomogeneous materials characterized by simultaneous permittivity, permeability, and cross-coupling (as in optical activity) arbitrary full tensors. The analysis takes into account arbitrary cross sections, and results in spurious-mode suppression, complex-mode computation, and the possibility of alternatively specifying the frequency or the complex propagation constant as an input parameter. In this way, many novel classes of waveguides with promising applications, such as chirowaveguides and chiroferrite-waveguides, can be analyzed. The formulation leads to a quadratic sparse eigenvalue problem which is transformed into a sparse generalized eigenvalue problem. This eigensystem is solved by the subspace method, the sparsity of the matrices being fully utilized. The proposed method has been validated by analyzing waveguides with biisotropic and bianisotropic materials. The agreement with previously published data is found to be excellent.

The propagation characteristics of hybrid modes in the circular cylindrical and coaxial line gyrotropic chirowaveguides are studied using the technique of separation variables. First, the transverse components of electric and magnetic fields are expressed in terms of the longitudinal components of [Mathematical Expression Omitted] and [Mathematical Expression Omitted]. Then, numerical results are presented for the dispersion behavior and cut-off frequencies as well as the field distributions of hybrid E[H.sub.0,1] and H [E.sub.n,1], with the effects of different electromagnetic parameters of gyrotropic chiral material taken into consideration. It is shown that the process of mode bifurcation also takes place in the gyrotropic chirowaveguides; this is similar to the cases of reciprocal chirowaveguides. But, gyrotropic chirowaveguides are nonreciprocal bianisotropic devices.

It is well known that transient electromagnetic waves in waveguides exhibit dispersion. Exact, closed-form expressions, which involve Bessel functions of the first kind, have been derived for the impulse response of a waveguide, but exact, closed-form expressions for more complex pulses are absent from the literature. In this paper, it is demonstrated that incomplete Lipschitz-Hankel integrals can be used to represent transient pulses in homogeneously filled waveguides. A continuous wave pulse is investigated in this paper, however, this technique can also be applied to a number of other transient waveforms. The resulting expressions are verified by numerically integrating the pulse distribution multiplied by the known impulse response.

The stationary phase Monte Carlo (SPMC) path integral method is applied to analyze electromagnetic wave propagation in transversely inhomogeneous media. A filter, which gives a stable result with respect to various Monte Carlo parameters and thus overcomes the difficulties previously associated with the multi-dimensional SPMC technique, is constructed to evaluate the propagation field. Numerical results are presented for a graded-index waveguide, and are in good agreement with those obtained by another independent path integral approach, viz., the split-step method.

In modes excitation problem of anisotropic waveguides it should be paid attention to the case of excitation sources with longitudinal components. In such case the usage of the basis of membrane functions of normal modes for the solution of the excitation problem may not lead us to unequivocal results because only transverse components of modes fields form a complete set of orthonormal basis on the waveguide cross section. In this paper it is shown tha in the presence of longitudinal currents it appears the additional terms in the excitation integral caused with as anisotropy of medium as the transversal derivatives of longitudinal currents.

In this paper we set out the bases of the near-complete analytical methodology that now exists for the design of long-wave optical systems. We follow the Gaussian beam-mode treatment of free-space propagation, extend it to cover the transformations produced by conic-section reflectors or lenses, and incorporate both the propagation steps and the lens transformations into a matrix formulation readily applicable to networks of such reflectors or lenses. We demonstrate in the process the theorems of Fourier Optics and keep explicit the vectorial properties of the beam-fields. We show how recent formulations of partial coherence have made it possible to include partially-coherent beams in the same methodology. For the design of high-performance systems, the inclusion of higher-order mode-dispersion must be fully understood, the vector properties must be recoverable, and the paraxiality on which the methodology rests must be critically assessed. This paper gives emphasis to these aspects and presents a single systematic formulation embracing all the elements.

For the first time, a study is made of leaky waves in anisotropic circular channel waveguides consisting of uniaxial crystalline material, in which the optical axis is on the plane which is defined by the propagation axis and one of the transverse coordinates axes. The analysis is based on the theory of coupled modes. Mathematical discretization of the continuum of radiation modes offers satisfactorily accurate solutions of the coupled-mode equations. The characteristics of leakage losses and the field distributions of leaky waves in a LiNbO3 waveguide are discussed on the basis of the numerical results.

This paper presents a study of both magnetostatic surface wave (MSSW) and magnetostatic volume wave (MSVW) propagation in multilayered magnetic thin films with noncollinear magnetizations. YIG/GGG/YIG structure is used, where YIG and GGG are the abbreviations for yttrium iron garnet and gadolinium gallium garnet, respectively. The layered film is in the (110) plane. Due to the existence of both cubic and induced in-plane uniaxial anisotropy fields in the two YIG films, the two magnetizations (M(sub 1) arrow to the right and M(sub 2) arrow to the right) are not aligned with the applied dc field. Since there is an arbitrary angle between M(sub 1) arrow to the right and M(sub 2) arrow to the right, there is a new configuration to study both MSSW and MSVW propagations. The interested MSVW propagation in the plane formed by M(sub 1) arrow to the right and M(sub 2) arrow to the right shows a different dispersion relationship from that in the direction perpendicular to the plane formed by M(sub 1) arrow to the right and M(sub 2) arrow to the right. For a given applied dc field normal to the film plane, MSVW is excited in the M(sub 2) arrow to the right layer, while MSSW is excited in the M(sub 1) arrow to the right layer. We have found that the angle between the two static magnetizations strongly affects the dispersion relationship. In addition, the effect of the separation between the two magnetic layers on the dispersion and time delay has been studied.

We study the accuracy and convergence of the method of moments for numerical scattering computations for an important benchmark geometry: the infinite circular cylinder. From the spectral decomposition of the electric-field integral equation for this scatterer, we determine the condition number of the moment matrix and the dependence of solution error on the choice of basis functions, discretization density, polarization of the incident field, and the numerical quadrature rule used to evaluate moment-matrix elements. The analysis is carried out for both the TM polarization (weakly singular kernel) and TE polarization (hypersingular kernel). These results provide insights into empirical observations of the convergence behavior of numerical methods in computational electromagnetics. Index Terms--Boundary integral equations, electromagnetic scattering, error analysis, moment methods, numerical analysis.

Some new ideas for reconstructing permittivity profiles in planar and cylindrical objects illuminated by TEM-, TE- or TM-polarized waves are presented in this paper. For a planar medium, an improved renormalization technique along with a revised version of the nonlinear Riccati differential equation describing the direct problem are introduced. A nonlinear Riccati-similar differential equation for the cylindrical case has also been derived here for the first time, which helps reconstructing radially varying permittivity profiles in a way parallel to that of the planar case. The above-mentioned renormalization technique has been used for the cylindrical case as well to solve the inverse problem making use of a Hankel transform. The method represents fundamental bases for a three-dimensional generalization, which is essential for microwave imaging used, e.g., in biomedical applications and for the diagnostic of diseases in trees and vegetation. A known permittivity profile has been taken to generate synthetic reflection-coefficient data by solving the nonlinear equations describing the direct problems using MATLAB. These data have been used in conjunction with the proposed technique to reconstruct the permittivity profile. About 50-100 data points over the wavelength range from a minimum value (ranging from one-tenth to one-fifth of a typical length in the structure) to infinity have been used for the reconstruction. Reconstructed profiles have been compared to the original ones for a number of cases. Deviations of less than 2% have been achieved. Index Terms--Electromagnetic scattering, inverse problems, microwave imaging, permittivity, remote sensing.

A three-dimensional (3-D) multiresolution analysis procedure similar to the finite-difference time-domain (FDTD) method is derived using a complete set of three-dimensional orthonormal bases of Haar scaling and wavelet functions. The expansion of the electric and the magnetic fields in these basis functions leads to the time iterative difference approximation of Maxwell's equations that is similar to the FDTD method. This technique effectively models realistic microwave passive components by virtue of its multiresolution property; the computational time is reduced approximately by half compared to the FDTD method. The proposed technique is validated by analyzing several 3-D rectangular resonators with inhomogeneous dielectric loading. It is also applied to the analyses of microwave passive devices with open boundaries such as micrstrip low-pass filters and spiral inductors to extract their S-parameters and field distributions. The results of the proposed technique agree well with those of the traditional FDTD method. Index Terms - FDTD method, Haar wavelets, multiresolution analysis.

Printed-circuit lines exhibit interesting behavior due to leakage of power. We have attempted to work toward a more profound understanding of uniplanar circuit properties when it comprehends planar transmission lines. Our work has focused on the slotline. We realized that the solution of its dispersion equation is multivalued. This enabled us to identify and report a new leaky wave on the slotline. The leaky wave brings down the upper cutoff frequency of the bound wave propagating over the slotline due to overlapping of the bound- and leaky-mode regions. For this case, we present some simple closed-form formulas providing this frequency limit when there is a frequency gap or when simultaneous propagation of the bound and the first or second leaky wave occurs. Propagation of the bound and leaky wave at the same time is a straightforward consequence of the multivalued nature of the solution of the dispersion equation. Evolution of the real and complex improper solutions of the equation in dependence on slotline dimensions demonstrates this clearly. We believe that conclusions drawn for the slotline also hold generally for other printed-circuit lines. Index Terms--Cutoff frequencies, electromagnetic surface waves, leaky waves, operation modes on slotlines, printed-circuit lines, slotlines.