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This letter proposes a high isolation two‐element multiple input multiple output (MIMO) antenna by using a wideband pixel neutralization line (NL). The design procedures are simplified as follows: (1) Obtaining the Y‐parameters of the original two‐element antenna with a grid of microstrip stubs, and discrete ports are inserted among microstrip stubs; (2) obtaining the binary codes of the optimum route. Importing Y‐parameters into MATLAB, and using a genetic algorithm to obtain the optimum connection route by design formulas upon scattering matrix which guarantees high isolation; (3) translating the binary codes into the actual connection metallic lines; (4) adding the designed pixel NL and appropriate matching branches into EM simulator to optimize the antenna; (5) obtaining a high isolation two‐element antenna. The original two‐element antenna has poor isolation with the main path coupling, and the pixel NL provides an auxiliary coupling path between two elements. By adjusting pixel NL, the magnitude strengths of two coupling signals realize the same, while the phases are exactly opposite. Therefore, the wideband high isolation between antenna elements is realized. To verify the practicability of the proposed pixel decoupling neutral line, a reference and proposed two‐element MIMO antennas are fabricated and measured. In the experiment, the isolation of the proposed two‐element antenna with an edge‐to‐edge distance of 0.0943λ0 (λ0 is the wavelength in free space at the center frequency) is enhanced by about 17 dB in the working frequency band from 0.975 to 1.025 GHz. Besides, an L‐typed feeding network is added to guarantee a good matching condition. The proposed two‐element antenna has a size of 0.617λ0 × 0.667λ0, and the dimension of each radiation patch is 0.3267λ0 × 0.0725λ0. The proposed GA algorithm‐based decoupling technique has a significant superiority over traditional ones. Efficient, simple, and one‐time EM simulation are its major advantages, which can liberate the RF engineer from the heavy debugging work. [ABSTRACT FROM AUTHOR]

An inclusive method is introduced for the analysis of different types of inductively loaded rectangular waveguides with dielectric and/or metallic obstacles. The proposed method utilizes the efficiency of the generalized scattering matrix (GSM) method on scattering analysis and the flexibility of the method of moments on problem configuration. The inductive metallic discontinuities are treated as a dielectric medium with high conductivity and the scattering analysis is accelerated by several cost reduction attempts in conjunction with GSM method and procedure of method of moments. The examined approach is tested against several structures including a metal insert filter, an H‐plane filter, and a dielectric‐metal obstacle‐loaded waveguide both for the dominant mode region and the double‐mode region. The convergence analyses on the number of calculated modes and the size of the discretized cells in the computational procedure are carried out for a comprehensive explanation of the numerical analysis. The accuracy of the method is compared to commercial software based on the finite element method. The proposed method is particularly competent for the frequency analysis of metallic and inhomogeneous dielectric discontinuities horizontally aligned in cuboid shapes. [ABSTRACT FROM AUTHOR]

In this letter, a passive ultra‐wideband balun with high balance performance is proposed. The balun is realized by using a pair of planar spiral coupled transmission lines and a capacitor which is responsible for the capacitive balance compensation. The straight‐forward scattering matrix derivation shows that the proposed structure can achieve full output balances both in amplitude and phase. For demonstration, two baluns with and without the compensating capacitor were designed and fabricated in a 65‐nm complementary metal‐oxide‐semiconductor (CMOS) process. The measured results show that the compensated balun features a measured insertion loss ≤5.2 dB and a return loss ≥10 dB from 3.6 to 8.1 GHz. Within such a wide frequency range, the measured amplitude and phase difference are ≤0.2 dB and 1.8°, respectively, which are much better than its uncompensated counterpart. [ABSTRACT FROM AUTHOR]

The well‐known symmetry property of the scattering matrix relative to propagating modes becomes tricky in the case of arbitrary polarization or arbitrary complex modal functions, as in the case of waveguide polarizers and ortho‐mode transducers. A straightforward transformation between different modal bases for the guided waves leads to a loss of symmetry. Only by gaining a deeper insight on the properties of the scattering matrices and with separate transformations for the incident and reflected waves is symmetry recovered. [ABSTRACT FROM AUTHOR]

ABSTRACT In this article, a novel approach based on differential transfer matrix method is proposed for fast analysis and optimization of wideband planar tapered directional couplers. In this method, both even and odd modes can be analyzed independently to obtain overall scattering matrix. The new method accelerates the optimization time considerably in planar structures. An 8.34 dB tapered coupler in the frequency band of 1-12 GHz is designed and optimized in the form of offset stripline structure. The experimental result shows good agreement with theory. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1795-1798, 2014 [ABSTRACT FROM AUTHOR]

ABSTRACT A comparative study of two techniques to analyze double screen frequency selective surface (FSS) is presented. The FSS are composed with perfectly conducting rectangular patch elements. Numerical and experimental results are presented. The two techniques are the scattering matrix (SM) and the spectral domain analysis. The study allowed us to set up main advantages and constraints of these techniques and define which one should be used for particular FSS geometries and conditions. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2206-2209, 2013 [ABSTRACT FROM AUTHOR]

A compact varactor-tuned planar inverted-F antenna is introduced for digital video broadcast-handheld (DVB-H) applications. The antenna size is 20 × 40 × 5 mm3, making it particularly suitable as an internal antenna. A full-wave simulator is used to calculate the scattering matrix of the antenna as a two port network. A circuit model including the two-port antenna and its tuning circuitry is simulated using a circuit simulator. The simulation results show that the antenna is continuously tunable within the entire frequency range of the DVB-H standard, 470-702 MHz. The antenna is prototyped and tested. The measured results are in agreement with the simulation data. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2635-2638, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.21728 [ABSTRACT FROM AUTHOR]

Compact rectangular waveguide 90° twist is studied. The twist transformer region is a square waveguide section with two stepped corner ridges. The twist can provide the 40-dB return-loss level over the rectangular waveguide operating band if the wide and narrow waveguide wall dimensions are in the ratio of 2:1. The twist lengths are less than the rectangular waveguide half-wavelength at the central frequency of the chosen operating band. The design results are confirmed by the results of real device measurements. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 851–854, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24161 [ABSTRACT FROM AUTHOR]

This paper describes investigations of the longitudinally ferrite circulator realized in slot-line technology. The proposed planar structure of circulator allowed to achieve small dimensions of the device. Also, the insertion losses comparable to ones actually published for microstrip structures were obtained. The basic steps of design procedure using scattering matrix of the circulator arrangement were presented. The S-parameters of circulator were simulated and next verified via experiment. The operation bandwidth from 12 to 19 GHz with reflection loss and isolation better than 10 dB and average insertion loss 2.5 dB were measured for fabricated model of circulator. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 692–696, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22246 [ABSTRACT FROM AUTHOR]

This paper provides a new step towards a mathematical foundation for S-matrices. It introduces a new operation, the S-matrix multiplication, and defines the mathematical group of S-matrices, allowing the power of Group Theory to be applied to S-parameter network analysis. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 179–183, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22070 [ABSTRACT FROM AUTHOR]

The authors propose to use microelectromechanical systems (MEMS) to produce novel phase shifters based on an electronically reconfigurable high-impedance surface (HIS). Typically, HIS is a textured metal surface with reactive impedance varying from an initial value to a very high value. Such phase shifters can be developed with introducing a surface with variable impedance in, e.g., a rectangular metal or dielectric rod waveguide. Placed along narrow walls of the rectangular metal waveguide or adjacent to the dielectric waveguide, the HIS affects the propagation constant, which results in changing the phase of the propagating wave. The authors manufactured a prototype of the microelectromechanical systems-based HIS consisting of a dielectric layer placed on a ground plane, and two arrays of metal patches. The gap between the upper and lower arrays of patches was fixed and filled with SiO2. The measured phase of the wave reflected from the prototype HIS varies in the range of 50°, and its insertion loss is below 0.5 dB (out of resonance). © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2570–2573, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21997 [ABSTRACT FROM AUTHOR]

Multivia interconnect structures for printed circuit boards (PCBs) have been analyzed by decomposing the geometry into exterior and interior structures. In this paper, we include the effects of dielectric substrates in the exterior structure. The exterior problem is solved by using the method of moments (MoM). The impedance-matrix elements are evaluated by using a fast method of calculating the layered-medium Green's function. The RWG basis functions are also utilized. Combined with the Foldy–Lax equation for solving the interior structure of a cylindrical vias problem, we analyze the transmission and scattering characteristics of interconnects with via structures. The numerical results of the scattering matrix are obtained for various via structures with a through-hole via and a single-layered via. The results obtained using commercial modeling tools such as HFSS and IE3D are also compared. The differential signaling of common and differential modes of coupled interconnects are illustrated. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 446–452, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21013 [ABSTRACT FROM AUTHOR]

A fast method for analyzing optical waveguides with the use of an improved Fourier series method and an absorbing boundary condition of perfectly matched layer (PML) is proposed. The numerical examples show that the computing cost, calculated accuracy, and convergent speed with the PML condition have been saliently improved, as compared to without the PML condition. The validity of the proposed method have been confirmed via comparison with other methods and measurements. The proposed method can be easily extended to 3D problems. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 263–268, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20961 [ABSTRACT FROM AUTHOR]

A high-order vector finite-element method (FEM) is presented for the analysis of 3D frequency-selective structures (FSSs). The asymptotic waveform evaluation (AWE) technique is combined with the FEM to perform fast frequency and angular sweeps. Reflection/transmission characteristics of several frequency-selective structures are calculated and compared with the existing results. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 259–263, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11032 [ABSTRACT FROM AUTHOR]

In this paper we present a computational electromagnetic model for tree scattering at VHF/UHF frequencies. A structure model with dielectric cylinders is being used to simulate trees with bare branches. The method of moments (MoM) solution of the volume integral equation is computed for the tree scattering signature. An efficient numerical algorithm based on the sparse matrix iterative approach (SMIA) is used to solve the matrix equation. The SMIA decomposes the impedance matrix into a sparse matrix for the near interactions, and a complementary matrix for the far interactions among the cylindrical sub-cells of the tree structure. Using a direct sparse solver to estimate the strong interaction part, we iteratively include the weak interaction contribution in order to update the solution. The key feature of the SMIA approach is that very little iteration is required to obtain convergent solutions. We have applied the SMIA tree scattering model to calculate scattering from various simulated trees with up to several hundreds of branches. Solutions obtained from the SMIA method agree very well with the solutions obtained using exact matrix inversion and the conjugate gradient method (CGM). Compared to the CGM, the SMIA approach reduces the number of iterations by a factor of more than a hundred and provides a much faster numerical solution scheme for computing tree scattering. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 198–202, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11014 [ABSTRACT FROM AUTHOR]

This Letter presents an efficient technique for analyzing multiple frequency-selective surfaces (FSSs) with noncommensurate periodicities based on the discrete plane-wave spectrum (DPWS) expansion method. In this method, the tangential electric fields at the interfaces of the screens are first expanded in a set of transverse electric and transverse magnetic waves, and the responses of the individual FSS screens are derived for each of these waves. The transmission and reflection characteristics of the composite structure are then computed in an iterative manner, circumventing the need for matrix inversions, which can be extremely expensive in terms of CPU time and memory for noncommensurate FSSs. Representative numerical examples are presented to illustrate the computational advantage gained by using the proposed approach as opposed to the conventional generalized scattering matrix technique. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 23–27, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10506 [ABSTRACT FROM AUTHOR]

In this Letter a hybrid approach combining the finite-element method and the method of lines is presented for solving the scattering problems of irregular geometry and inhomogeneity. In this approach, the FEM is used to treat the region with complicated geometry and inhomogeneous material profile, and the MoL acts as a radiation boundary condition for the FEM. The MoL can also treat layered regions. Because of the flexibility of the FEM and the semianalytical nature of the MoL, the flexibility, efficiency, and accuracy of these two methods are maintained. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 134–138, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10395 [ABSTRACT FROM AUTHOR]

A surface-based integral-equation formulation for coupled electromagnetic and circuit simulation is presented. The approach is sufficiently general to model arbitrarily shaped structures and high-frequency skin effects. The formulation is implemented in both an equivalent circuit form for spice compatibility, and in a more general form as a coupled-matrix system outside spice. The overall approach can be interpreted as either a modified surface-only partial element equivalent circuit approach, or as a circuit-coupled version of the surface-based method of moments. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 103–106, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10386 [ABSTRACT FROM AUTHOR]

An efficient method is presented for transforming the matrix of the method of moments obtained by the expansion of the unknown surface currents with pulse basis function and the use of point match testing to a matrix with wavelet basis and testing functions. When the electromagnetic scattering object is a dielectric or object under oblique plane-wave incidence, more than one equivalent surface current component exists at the object surface. When these currents are connected into one current vector in the method of moments, there must be some discontinuities between the current components. These discontinuities make the direct wavelet transform to the whole MoM matrix inefficient and not equivalent to the use of the wavelet functions in the expansion of the unknown currents and the testing. Therefore, the wavelet transform must be constructed in a different way to avoid these discontinuities. Here, the proper wavelet transform that is equivalent to the use of the wavelet functions in the MoM, which avoids such discontinuities, is presented. This transform is referred to as wavelet subtransform. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 130–134, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10394 [ABSTRACT FROM AUTHOR]

This paper investigates an electromagnetic preprocessing technique that transforms the voltages that are induced in a nonuniformly spaced array containing real antenna elements to a set of voltages that will be produced in a uniform linear virtual array (ULVA) containing omnidirectional isotropic point radiators. The objective here is that, in the processing methodology, we would like to include various electromagnetic effects like mutual coupling between the antenna elements, the presence of near-field scatterers, and the platform effects on which the antenna array is mounted. The preprocessing is carried out using a least squares method, which generates a transformation matrix for the set of induced voltages in the real array. This transformation matrix, when applied to the actual measured voltages, yields an equivalent set of voltages that will be induced in the ULVA. Then, a direct data domain superresolution technique like the matrix pencil method is applied to the processed voltages to yield the DOA for the various signals of interest. Numerical results are presented to illustrate the efficiency and accuracy of this method. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 335–340, 2002. [ABSTRACT FROM AUTHOR]

The face-centered node-point technique, developed earlier for scattering applications, is applied to the calculation of resonance frequencies of inhomogeneous dielectric resonators. The described method leads to a well-conditioned matrix system suitable for numerical solution, which is not the case when the permittivity is high and conventional solution techniques (e.g., pulse functions with cell-centered point matching) are employed. In this work, we concentrate on resonators having the shape of a parallelepiped, for which there are relatively few computational results in the literature, although the method can accommodate arbitrarily shaped structures. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 356–359, 2002. [ABSTRACT FROM AUTHOR]

A time-domain finite-element method (TDFEM) is presented for simulating the radiation and scattering from cavity-backed microstrip patch antennas. The perfectly matched layer (PML) is utilized to efficiently truncate the TDFEM solution domain. The higher order vector basis functions are adopted to accurately represent unknown fields. Numerical examples are given to demonstrate its efficacy. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 251–254, 2002. [ABSTRACT FROM AUTHOR]

An analytical technique, called the scattering matrix method, is developed to analyze the scattering of a plane wave from a nonuniform ferrite cylinder. It is proved that the derived formulas for nonuniform ferrite cylinders can be degenerated to the formulas for uniform ferrite cylinders published in the literature. The characteristics of scattering by ferrite cylinders with a linear profile are investigated versus applied magnetic fields and wave frequencies. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 268–272, 2002. [ABSTRACT FROM AUTHOR]

This paper presents numerical results for the dielectric polarizability of canonically shaped homogeneous scatterers: cube, tetrahedron, and octahedron. The method is based on solving the integral equation for the static scalar potential on the surface of the scatterer by the method of moments. Easy-to-use interpolation formulas are given for the polarizabilities as a function of the permittivity. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 60–64, 2002. [ABSTRACT FROM AUTHOR]

We discuss a general method for calculations of scattering matrices of coupled waveguiding structures using group theory. As an example, we present the calculated matrices for a structure consisting of two circular coupled waveguides with different symmetries and with coupling elements of different natures. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 446–449, 2001. [ABSTRACT FROM AUTHOR]

A sparse technique for the dense matrix of the method of moments (MoM) is implemented to the electromagnetic scattering of a 3-D arbitrary conducting object for the first time. The numerical examples for the plane-wave scattering of a conducting sphere with 0.2 and 0.4λ show that the surface current densities of OSMEI and MoM agree well. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 273–276, 2001. [ABSTRACT FROM AUTHOR]

When analyzing electromagnetic scattering by three-dimensional perfectly conducting bodies of arbitrary shape, the surface modeling is often affected by triangulation, and in turn, triangular-patch basis functions are used for expanding the unknown surface current. In this paper, we apply a wavelet transformation to transform the triangular-patch basis functions to a new set of basis functions, which can be interpreted as wavelet combinations of the original basis functions. The new basis functions can lead to a matrix representation of the operator equation that is more localized and which, by proper thresholding, can be rendered sparse. Alternatively, they can lead, via an impedance matrix compression (IMC) approach, to a matrix equation that is compressed (rank reduced). The solution of either the sparse or the compressed matrix equation can yield fairly accurate results with less computational effort. The dependence of the results on ordering of the original triangular-patch basis functions prior to the transformation is discussed. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 21: 359–365, 1999. [ABSTRACT FROM AUTHOR]

A dual-band circular waveguide polarizer for TTC (telemetry, tracking, and command) applications is presented. The structure is composed of two corrugated metal sheets inside a circular waveguide allowing easy manufacturing and low cost. A rigorous CAD which combines the mode-matching and the finite-element techniques (MM–FEM) permits us to obtain the generalized scattering matrix (GSM) and to take into account the higher order mode interaction between the step discontinuities. The experimental polarizer results show excellent agreement with theory. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 20: 99–103, 1999. [ABSTRACT FROM AUTHOR]

A rigorous method for analyzing axisymmetric radiating structures, using 2-D finite-element techniques and an expansion in spherical harmonics, is presented. The structure, represented by an equivalent multipole, is entirely characterized by its scattering matrix at the interfaces. The radiation patterns and input impedances obtained for several antennas are presented. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 20: 8–13, 1999. [ABSTRACT FROM AUTHOR]

A new wire-junction node for modeling a junction with two wires of different radius using the TLM method is presented. The scattering matrix of the node is provided, and the numerical results are compared with the moment method solutions traditionally used for modeling wires and wirelike structures. © 1998 John Wiley & Sons, Inc. Microwave Opt Technol Lett 19: 103–107, 1998. [ABSTRACT FROM AUTHOR]

A method for the calculation of the generalized scattering matrix (GSM) of an arbitrarily shaped discontinuity on a rectangular waveguide with 2-D TLM is presented. The calculation procedure is based on the expansion of the TLM voltage impulses in the amplitudes of the modes supported by the waveguide. Results of the analysis of inductive irises on a rectangular waveguide are presented. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 15: 392–395, 1997. [ABSTRACT FROM AUTHOR]

A clever way to simulate Numerically Matched Loads is presented and applied in the mathematical framework of 3-D spectral domain analysis. The numerically matched loads already have been developed in the particular case of the spectral domain approach using a set of subsectional rooftop expansion and testing functions in the moment method. In order to properly model more complicated structures, we propose in this letter an extension of the NML simulation where triangular subdomain functions are used as both expansion and testing functions in the moment method. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 15: 373–377, 1997. [ABSTRACT FROM AUTHOR]

We present a new application of the recursive T-matrix algorithm to calculate the scattered field from a single or multiple metallic cylinders of arbitrary shapes. Using the equivalence theorem, each metallic object is replaced with small metallic cylinders along its perimeter; then scattered fields are calculated using the recursive T-matrix algorithm. Results are verified by those in the literature and by analytical calculations. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 15: 360–363, 1997. [ABSTRACT FROM AUTHOR]

In order to obtain a more accurate, efficient representation of scattering behavior for radar targets and to allow better extrapolation of scattering data from the sampled frequency band to a wide range, a modeling procedure is presented for processing scattering data containing high-order diffraction terms. In this procedure, a more realistic fα model for scattering and the maximum-likelihood algorithm are employed. In the model, the restriction of α being an integer multiple of ½ has been removed, which results in highly accurate estimates. In addition, the genetic algorithm is used to overcome the issue of converging to local minima. An iterative simplex downhill minimization method is used to accelerate the optimization process. Computer simulation shows superior noise performance of this modeling procedure. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 15: 36–39, 1997. [ABSTRACT FROM AUTHOR]

A hybrid method that combines the finite-element method (FEM) and the shooting-and-bouncing-ray (SBR) method is presented to compute scattering by large bodies with small protruding scatterers. In the method, the field equivalence principle is employed to replace the protruding scatterers by a set of equivalent electric and magnetic currents. The total scattered field then becomes the superposition of the field scattered by the large body without protrusions, which is calculated with the use of the SBR method, and the field radiated by the equivalent currents in the presence of the large body, which is also calculated with the use of the SBR method with the aid of the reciprocity theorem. The required equivalent currents are computed with the use of the FEM, which permits the handling of complex material composition of the protrusions. Two-dimensional examples are presented to demonstrate the feasibility of the proposed method. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 14: 78–84, 1997. [ABSTRACT FROM AUTHOR]

An alternative technique that combines the matrix pencil (MP) method and the GTD-based model is presented to estimate scattering center parameters including frequency dependence, down range, and amplitude from computed and measured scattering field data. The technique does not employ the time-consuming iterative approach to estimate frequency dependence, so it has high computational effectiveness. Numerical results show the validity of the method presented in this Letter. If higher accuracy is required, one may take the results from this technique as initial estimates, then use the maximum-likelihood algorithm to improve the accuracy. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 14, 244–247, 1997. [ABSTRACT FROM AUTHOR]

In this article die boundary value technique for the. electromagnetic analysis employed to investigate the features of the Mueller scattering matrix for two parallel büsotropic chiral circular cylinders. and the multiple scattering effect between these two different cylinders is also taken into consideration. Numerical results are presented to show the influences of chirality as well as the incident wave direction on all the elements of the Mueller matrix in detail. [ABSTRACT FROM AUTHOR]

There is no rigorous definition of the S matrix for the electro-optic components. This article proposes such a characterization, based on usual microwave theory. Transmission-line models, reflection coefficient, and available gain definitions are also proposed. [ABSTRACT FROM AUTHOR]

Four scalar complex parameters (dieletric permittivity, magnetic permeability, chirality parameter, and nonreciprocity parameter) characterize general biisotropic materials. In this communication. possible techniques for material parameter measurement are addressed. Procedures are based on free-space measurements of planewave reflection from the transmission through a biisotropic slab. Explicit formulas expressing the material parameters in terms of scattering matrix coefficients are given for measurements at normal incidence. [ABSTRACT FROM AUTHOR]

The main problem in polarimetric measurement is to retrieve all the properties (phase and magnitude) of the scattering matrix of the studied object. In most cases the proposed techniques [1-3] are very complicated and are not adaptable to intensive application, as in the industrial domain. The development of an original technique is proposed here. The technique is very efficient and simple to use. It is based on a modification of an existing technique developed in Reference [1]. The main advantage, are the facility of placement of the targets and the fact that there is no need to know the distances between the calibration targets and the emission/reception system. [ABSTRACT FROM AUTHOR]

In this work, a new property for the generalized scattering matrix of microwave networks is derived and numerically verified. Apart from its theoretical significance, this property can be very useful for rapid verification of numerical methods such as Mode Matching among others. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 356–358, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23085 [ABSTRACT FROM AUTHOR]

In this Letter a new type of combined field integral equation (CFIE) is proposed and applied for electromagnetic scattering by three-dimensional dielectric objects of arbitrary shape. In this formulation, traditional CFIE is applied outside the object, and inside the object the electric and magnetic field integral equations are combined by changing their roles. This formulation gives a more stable solution than the traditional CFIE when the method of moments with Galerkin's type testing and RWG functions is applied. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 3–5, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10500 [ABSTRACT FROM AUTHOR]

TEM-wave scattering from a coaxial line with a material-filled cavity is studied to obtain the reflection and transmission coefficients in a rapidly convergent series. Their behaviors are studied in terms of medium permittivity, coaxial geometric structure, and frequency. The measurement is performed with a water-filled cavity at 1–3 GHz, and is compared with the theory. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 25: 285–287, 2000. [ABSTRACT FROM AUTHOR]

The perfectly matched layer (PML) absorbing boundary condition has been used for a wide range of applications since its introduction in 1994. Most of these applications have used the PML in a uniform air-filled zone around a nonair scatterer. This paper describes the application of the PML to a geophysical prospecting problem where the PML is applied in a conductive host material containing the scatterer. The conductivity profile is optimized using parameter estimation. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 25: 253–255, 2000. [ABSTRACT FROM AUTHOR]

Two test procedures (based either on principal minors or on singular values) have previously been proposed for detecting the presence of any 180° phase discrepancies in the transmission-coefficient measurements obtained by automatic network analyzers for multiport rectangular-waveguide components. The additional studies conducted in the present paper have confirmed that the test procedure based on principal minors tends to yield low reliability, and is thus not suitable for general application. Yet another test procedure (based on determinant magnitudes) has been proposed as well; not only is it simple to implement and use, but it has also been found to be more reliable than the test procedure based on singular values. ©2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 24: 91–93, 2000. [ABSTRACT FROM AUTHOR]

An original procedure is proposed for the experimental determination of the characteristic impedance matrices of multiconductor waveguides. Experiments are based on multiport S-parameter measurements and multimode TRL calibration involving symmetrical as well as asymmetrical coupled-strip lines. Measured results are compared to theoretical ones. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 22: 429–431, 1999 [ABSTRACT FROM AUTHOR]

An asymmetric and very compact orthomode transducer for dual-frequency-band applications with a high polarization purity is proposed and analyzed by means of a hybrid full-wave characterization based on the generalized admittance matrix (GAM) and the generalized scattering matrix (GSM) obtained with mode matching. An accurate, robust, and efficient computer code based on this procedure has been developed and used for the design of a dual-frequency OMT in the Ku-band. The numerical/experimental results for the structure confirm its excellent performance, i.e., low return and insertion losses, high isolation, and, especially, high polarization purity. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 21: 265–267, 1999. [ABSTRACT FROM AUTHOR]

The exact analytical solutions of lossless nonuniform transmission lines (NTLs) with a characteristic impedance function Zc(x)=Z0(1+kx)-ν are obtained. The two-port ABCD matrix and several numerical examples of the scattering matrix S of the NTLs are given. © 1998 John Wiley & Sons, Inc. Microwave Opt Technol Lett 17: 195–197, 1998. [ABSTRACT FROM AUTHOR]

The recent application of wavelet transforms in method-of-moments solutions for scattering problems is extended to cases involving metallic cylinders whose periphery contain a variety of length scale features ranging from smoothly varying large-scale features to rapidly varying small-scale ones. The basic idea is to first consider a periodic extension of the equivalent current in the arc-length variable with a period identical to the scatterer circumference, and then to expand this representation, using a set of periodic wavelets derived from a conventional basis of wavelets by a periodic extension. Using a Galerkin method and subsequently applying a threshold procedure, a substantial reduction in the number of elements of the moment-method matrix is attained without virtually affecting the solution accuracy. The proposed extension is illustrated by a numerical study of TM (transverse magnetic) scattering from a cylinder of elliptic cross section. [ABSTRACT FROM AUTHOR]

This article examines the polarimetric method of identification of a target in the presence of ground clutter. The clutter is modeled as a two-layer random medium. The complex scattering matrix for the clutter is obtained by using Born approximations carried to the second order to extract the crosspolarized scattered fields. The test target used is a loop of conducting wire oriented arbitrarily. It is found that the choice of polarization is one of the key factors if one has to identify targets in presence of clutter. This work does not take into account the mutual coupling between the target and the clutter sources. The important results are analyzed and discussed. [ABSTRACT FROM AUTHOR]