Showing papers in "IEEE Transactions on Microwave Theory and Techniques in 1991"
TL;DR: The author presents a method for the calibration of network analyzers that uses multiple, redundant transmission line standards to minimize the effects of random errors, and exhibits improvements in both accuracy and bandwidth over conventional methods.
Abstract: The author presents a method for the calibration of network analyzers. The essential feature is the use of multiple, redundant transmission line standards. The additional information provided by the redundant standards is used to minimize the effects of random errors, such as those caused by imperfect connector repeatability. The resulting method exhibits improvements in both accuracy and bandwidth over conventional methods. The basis of the statistical treatment is a linearized error analysis of the TRL (thru-reflect-line) calibration method. The analysis presented is useful in the assessment of calibration accuracy. It also yields results relevant to the choice of standards. >
1,168 citations
TL;DR: In this paper, a closed-form spatial Green's function for the open microstrip structure, especially with a thick substrate, is represented in the time-consuming Sommerfield integrals.
Abstract: The spatial Green's function for the open microstrip structure, especially with a thick substrate, is generally represented in the time-consuming Sommerfield integrals. Through the Sommerfield identity, a closed-form spatial Green's function of a few terms is found from the quasi-dynamic images, the complex images, and the surface waves. With the numerical integration of the Sommerfeld integrals thus avoided, this closed-form Green's function is computationally very efficient. Numerical examples show that the closed-form Green's function gives less than 1% error for all substrates and source-to-field distances. >
684 citations
TL;DR: In this article, experimental verification of analytic formulas for the dispersion and attenuation of electrical transient signals propagating on coplanar transmission lines is performed in the frequency domain over a terahertz range although the experiments are in the time domain.
Abstract: Experimental verification of analytic formulas for the dispersion and the attenuation of electrical transient signals propagating on coplanar transmission lines is presented. The verification is done in the frequency domain over a terahertz range although the experiments are in the time domain. The analytic formulas are obtained from fits to the full-wave analysis results. It is quantitatively verified that the full-wave steady-state solutions can be directly applied to the transient time-domain propagation experiments. Subpicosecond electrical pulses and an external electrooptic sampling technique are used to obtain the time-domain propagation data. From the Fourier transforms of the time-domain data both the attenuation and the phase information as a function of frequency are extracted. The dispersion and the attenuation characteristics are investigated for both coplanar waveguide and coplanar strip transmission lines. The investigation is carried out on both semiinsulating semiconductor and dielectric substrate materials. No observable losses caused by the semiconductor material are indicated. >
354 citations
TL;DR: A general theory for performing network analyzer calibration is presented and novel calibration procedures are derived which allow for partly unknown standards.
Abstract: A general theory for performing network analyzer calibration is presented. Novel calibration procedures are derived which allow for partly unknown standards. The most general procedure derived is called TAN and allows for five unknown parameters in the three calibration standards. The values of the unknown parameters are determined during the calibration procedure via eigenvalue conditions. The good performance of all the procedures has been shown experimentally. This wide spectrum of procedures using different calibration standards makes it possible to choose an optimal algorithm for any environment. >
340 citations
TL;DR: In this article, the Lanczos algorithm is modified to solve the required eigenmatrix equation efficiently and the reaction principle is used to provide a posteriori error estimate for use in adaptive mesh refinement.
Abstract: A novel method is presented for the analysis of dielectric waveguides. This method provides four major new contributions: (1) a transformation of variables is introduced that allows propagation constants to be computed directly; (2) H/sub 1/ (curl) tangential vector finite elements are applied to dielectric waveguides to obtain reliable approximate electromagnetic fields; (3) the Lanczos algorithm is modified to solve the required eigenmatrix equation efficiently; and (4) the reaction principle is used to provide a posteriori error estimates for use in adaptive mesh refinement. The method produces reliable solutions and applies to structures that contain both electric and magnetic inhomogeneities. The answers are refined adaptively to generate waveguide eigenmodes to a specified accuracy. Numerical results of an image guide, a microstrip transmission line, and a pedestal-supported stripline are shown. Computed solutions agree very well with previously published results. >
337 citations
TL;DR: In this paper, a modification to the time-domain finite-difference method (TDFDM) that uses a variable step size is investigated, where the entire computational volume is divided into a coarse grid with a large step size.
Abstract: A modification to the time-domain finite-difference method (TDFDM) that uses a variable step size is investigated. The entire computational volume is divided into a coarse grid with a large step size. A fine grid with a small step size is introduced only around discontinuities. The corresponding time increments are related to the spatial increments with the same ratio in order to minimize the numerical dispersion. The fields within the coarse and fine grids are found using the TDFDM, while an interpolation in space and time is utilized to calculate the tangential electric field on the coarse-fine grid boundary. This subgridding decreases the required computer memory and therefore expands the capability of the TDFDM. The technique is shown to be numerically stable and does not entail any extra numerical error. The method is applied to the calculation of waveguides and microstrips. >
273 citations
TL;DR: In this article, a quasi-optical method for solid-state power combining with applications to high-power millimeter-wave generation is discussed, which uses two-dimensional planar arrays of weakly coupled oscillators.
Abstract: A quasi-optical method for solid-state power combining with applications to high-power millimeter-wave generation is discussed. The approach uses two-dimensional planar arrays of weakly coupled oscillators. Limiting the strength of the coupling avoids multifrequency moding problems and simplifies the design. A radiating element is embedded in each oscillator so that the power combining is accomplished in free space. The concept which has been demonstrated with two prototype arrays, one using Gunn diodes and the other using MESFETs is discussed. A theoretical description of the coupled-oscillator arrays is presented for design purposes, and is used to investigate phasing problems and stability. Experiments are discussed which indicate that in-phase operation is facilitated by using a quasi-optical reflector element. which influences the operating frequency and coupling between the elements. Equivalent isotropic radiated powers of 22 W at 1% efficiency for a 16-element Gunn array and 10 W at 26% efficiency for a 16-element MESFET array which have been obtained at X-band are discussed. >
265 citations
TL;DR: In this article, the design of functional monolithic GaAs nonlinear transmission line (NLTL) is considered and the circuit design and diode design requirements for picosecond NLTL shock-wave generators and NLTL-driven sampling circuits are discussed.
Abstract: The GaAs nonlinear transmission line (NLTL) is a monolithic millimeter-wave integrated circuit consisting of a high-impedance transmission line loaded by reverse-biased Schottky contacts. The engineering of functional monolithic NLTLs is considered. Through generation of shock waves on the NLTL, the authors have generated electrical step functions with approximately 5 V magnitude and less than 1.4 ps fall time. Diode sampling bridges strobed by NLTL shock-wave generators have attained bandwidths approaching 300 GHz and have applications in instruments for millimeter-wave waveform and network measurements. The authors discuss the circuit design and diode design requirements for picosecond NLTL shock-wave generators and NLTL-driven sampling circuits. >
232 citations
TL;DR: In this article, a fast method of determining the elements of the equivalent circuit at all bias points without frequency limitations is presented, which takes into account the gate current of positively biased transistors and the symmetrical nature of the devices at low drain voltages.
Abstract: The application of GaAs field effect transistors in digital circuits requires a valid description by an equivalent circuit at all possible gate and drain bias voltages for all frequencies from DC up to the gigahertz range. An equivalent circuit is presented which takes into account the gate current of positively biased transistors as well as the symmetrical nature of the devices at low drain voltages. A fast method of determining the elements of the equivalent circuit at all bias points without frequency limitations is presented. Direct computation from analytical expressions, without iteration, allows this parameter extraction procedure to be used for real-time on-wafer parameter extraction. Large-signal calculations are possible by inserting the voltage dependences evaluation for the elements into suitable simulation programs, such as SPICE. >
200 citations
TL;DR: In this paper, a planar grid structure periodically loaded with transistors is presented, where the grid radiates and the devices combine quasi-optically and lock to each other.
Abstract: A 100-MESFET oscillator which gives 21 W of CW effective radiated power (ERP) with a 16-dB directivity and a 20% DC-to-RF conversion efficiency at 5 GHz is presented. The oscillator is a planar grid structure periodically loaded with transistors. The grid radiates and the devices combine quasi-optically and lock to each other. The oscillator can also be quasi-optically injection-locked to an external signal. The planar grid structure is very simple. All of the devices share the same bias, and they can be power and frequency tuned with a mirror behind the grid or dielectric slabs in front of it. An equivalent circuit for an infinite grid predicts the mirror frequency tuning. The planar property of the oscillator offers the possibility of a wafer-scale monolithically integrated source. Thousands of active solid-state devices can potentially be integrated in a high-power source for microwave or millimeter-wave applications. >
195 citations
TL;DR: In this article, an overview of tunable microwave and millimeter-wave bandpass filters realized in different technologies is presented, including magnetically tunable filters, magnetostatic-wave filters, evanescent waveguide filters and E-plane printed circuit filters.
Abstract: The authors present an overview of tunable microwave and millimeter-wave bandpass filters realized in different technologies. Some general design principles are described. Recent progress in the performance of various tunable filters is reported. The authors survey magnetically tunable filters (ferrimagnetic resonance filters, magnetostatic-wave filters, evanescent waveguide filters, E-plane printed circuit filters), electronically tunable filters, and mechanically tunable filters. The typical performance parameters are summarized. This comparison shown that none of these devices can simultaneously satisfy all requirements for perfect tunable filters. For microwave systems where multioctave tuning is essential, a YIG filter is an obvious choice. In systems where the requirement of high power handling capability combined with low insertion loss, predominates, mechanically tunable filters and magnetically tunable E-plane filters are recommended. If the tuning speed is a crucial requirement, varactor-tuned filters or E-plane filters with ferrite toroids are devices of choice. For millimeter-wave design, the most promising structures are ferrimagnetic resonance filters utilizing hexagonal ferrite resonators or, up to 60 GHz, magnetically tunable E-plane printed circuit filters. >
TL;DR: In this paper, an approach for measuring the permittivity of dielectric materials by means of a microstrip ring resonator is presented, which is used in conjunction with the variational calculation of the line capacitance of a multilayer microstriplike transmission line.
Abstract: An approach for measuring the permittivity of dielectric materials by means of a microstrip ring resonator is presented. The method is used in conjunction with the variational calculation of the line capacitance of a multilayer microstriplike transmission line to compute the effective permittivity and hence the resonant frequency of the ring. The results are compared with measurements made in X-band waveguide cavity-by-cavity perturbation techniques and tend to confirm that microstrip resonators can be used for dielectric measurements. However, for materials having a large dielectric constant, comparative results seem to diverge rapidly. >
TL;DR: In this paper, the frequency-dependent resistance and inductance of uniform transmission lines are calculated with a hybrid technique that combines a cross-section coupled circuit method with a surface integral equation approach.
Abstract: The frequency-dependent resistance and inductance of uniform transmission lines are calculated with a hybrid technique that combines a cross-section coupled circuit method with a surface integral equation approach. The coupled circuit approach is most applicable for low-frequency calculations, while the integral equation approach is best for high frequencies. The low-frequency method consists in subdividing the cross section of each conductor into triangular filaments, each with an assumed uniform current distribution. The high-frequency method expresses the resistance and inductance of each conductor in terms of the current normal to the surface. An interpolation between the results of these two methods gives very good results over the entire frequency range, even when few basis functions are used. Results for a variety of configurations are shown and are compared with experimental data and other numerical techniques. >
TL;DR: In this article, a unified solution for full-wave computation of losses in a general multilayered planar transmission line is presented, which includes material losses (dielectric and conductor losses), losses due to radiation leakage, and losses caused by leakage of power to source-free characteristic modes (surface-wave or waveguide modes, for example) of the multilayer geometry.
Abstract: A unified solution for full-wave computation of losses in a general multilayered planar transmission line is presented. It includes material losses (dielectric and conductor losses), losses due to radiation leakage, and losses caused by leakage of power to source-free characteristic modes (surface-wave or waveguide modes, for example) of the multilayered geometry. A spectral-domain moment method is used with the Galerkin testing procedure. Significant modification of the conventional spectral-domain analysis of planar transmission lines is necessary in enforcing proper boundary conditions in the Galerkin testing procedure and, more importantly, in accounting for poles and branch cuts in the complex Fourier transform domain in order to rigorously account for the different loss mechanisms discussed. Results for a few representative geometries, namely, strip and/or material loss in a microstrip line and a slotline, surface parallel plate mode leakage loss in a conductor-backed slotline and a two-layer stripline, and radiation loss in a single and a coupled stripline at the interface between two infinite mediums, are presented to demonstrate these various loss effects. >
TL;DR: In this article, a modified parallel-coupled microstrip line filter structure is presented, which improves the filter upper stopband rejection by at least 15 dB and the filter response symmetry is also improved.
Abstract: A modified parallel-coupled microstrip line filter structure is presented. Using this new structure improves the filter upper stopband rejection by at least 15 dB, and the filter response symmetry is also improved. Compared with the traditional parallel-coupled filter, the modified filter used less space and is easy to lay out owing to its inline structure. Several examples show the performance improvement of the filters fabricated in both low-dielectric-constant (2.55) and high-dielectric-constant (10.2) substrates. >
TL;DR: In this article, a preliminary study of the application of simulated annealing (SA) to complex permittivity reconstruction in microwave tomography is presented, and the results show that SA can converge to an accurate solution in cases where the two deterministic methods fail.
Abstract: A preliminary study of the application of simulated annealing (SA) to complex permittivity reconstruction in microwave tomography is presented. Reconstructions of a simplified model of a human arm obtained with simulated noise-free data are presented for three different methods: SA, quenching, and a Newton-Kantorovich method. These results show that SA can converge to an accurate solution in cases where the two deterministic methods fail. For this reason SA can be used to get closer to the final solution before applying a faster deterministic method. >
TL;DR: In this paper, a full-wave analysis of shielded coplanar waveguide (CPW) two-port discontinuities based on the solution of an appropriate surface integral equation in the space domain is presented.
Abstract: A full-wave analysis of shielded coplanar waveguide (CPW) two-port discontinuities based on the solution of an appropriate surface integral equation in the space domain is presented. Frequency-dependent scattering parameters for open-end and short-end CPW stubs are computed using this method. The numerically derived results are compared with measurements performed in the frequency range 5-25 GHz and show very good agreement. From the scattering parameters, lumped-element equivalent circuits have been derived to model the discontinuities. The inductors and capacitors of these models have been represented by closed-form equations, as functions of the stub length, to compute the circuit element values for these discontinuities. >
TL;DR: In this article, Cauchy's technique for interpolating a rational function from samples of frequency responses and/or their derivatives is investigated, which can be used to speed up the numerical computations of parameters, including input impedance and RCS of any linear time-invariant electromagnetic system.
Abstract: Cauchy's technique for interpolating a rational function from samples of frequency responses and/or their derivatives is investigated. This technique can be used to speed up the numerical computations of parameters, including input impedance and RCS of any linear time-invariant electromagnetic system. This technique is utilized to find the far field of a slit conducting cylinder (TM incidence) over a bandwidth utilizing the information about the current and its derivatives at a few sample points. The numerical results are presented are in good agreement with exact computational data. This technique is a true interpolation/extrapolation technique as it provides the same defective result as the original electric field integral equation at a frequency which corresponds to the internal resonance of the closed structure. >
TL;DR: In this article, the surface impedance of YBa/sub 2/Cu/sub 3/O/sub 7-x/ thin films using a stripline resonator was measured.
Abstract: A report is presented on measurements of the surface impedance, Z/sub S/, of YBa/sub 2/Cu/sub 3/O/sub 7-x/ thin films using a stripline resonator. The films were deposited on LaAlO/sub 3/ substrates by off-axis magnetron sputtering. The authors obtained Z/sub S/ as a function of frequency from 1.5 to 20 GHz, as a function of temperature from 4 K to the transition temperature ( approximately 90 K), and as a function of the RF magnetic field from zero to 300 Oe. At low temperatures the surface resistance, R/sub S/, of the films shows a very weak dependence on the magnetic field up to 225 to 250 Oe. At 77 K, R/sub S/ is proportional to the square of the field. The penetration depth shows a much weaker dependence on the field than does R/sub S/. The origins of the magnetic field dependence of Z/sub S/ are also discussed. >
TL;DR: In this article, the vector parasite problem is studied in the context of finite-element solutions of Maxwell's equations for driven boundary-value problems, and an expanded weak form which combines the divergence equation with the conventional weak form of the double-curl equation is introduced.
Abstract: The vector parasite problem is studied in the context of finite-element solutions of Maxwell's equations for driven boundary-value problems. An expanded weak form which combines the divergence equation with the conventional weak form of the double-curl equation is introduced. This form is related to penalty methods where the penalty or weighting factor varies with the dielectric constant. The resulting algebraic system is identical to the Galerkin-Helmholtz operator on homogeneous subregions. Normal and tangential boundary conditions arise in terms of the divergence and curl of the field on the boundary which can be reexpressed as equivalent charges and currents. Computational results show the occurrence of two distinct types of parasitic modes in driven problems and their elimination with the formulation presented. Practical observations concerning the conditions which provoke spurious modes in these problems are reported. Spurious solutions arise from improper or unphysical boundary conditions, and the importance of careful specification of boundary-value problems is illustrated. Most conceptual difficulties with boundary conditions per se are removed when hybrid methods are used to couple the interior finite-element solution to the exterior problem. which focuses attention on the physics of the source distribution. >
TL;DR: In this paper, an improved interstitial microwave antenna design was investigated in static phantom experiments at 915 MHz and different insertion depths, and the presented dipole microwave antenna showed heating patterns which are concentrated on the dipole irrespective of the insertion depth.
Abstract: An improved interstitial microwave antenna design was investigated in static phantom experiments at 915 MHz and different insertion depths. Compared with conventional interstitial antennas, the presented dipole microwave antenna shows heating patterns which are concentrated on the dipole irrespective of the insertion depth. By analogy to interstitial radiotherapy, the microwave antenna allows a high concentration of energy in the target volume with as little damage as possible to the healthy surrounding tissue. The undesired heating of healthy tissue along the feeding line observed with conventional interstitial antennas is avoided. A lambda /4 sleeve on the feeding line (which does not radiate microwave energy itself to the surrounding tissue) transforms an open end, i.e. a high impedance at the generator end of the dipole antenna. The current flowing back along the outside of the outer conductor of the feeding line in the direction of the generator is zero at this point. Both dipole sections have the same terminating impedance. Since the lambda /4 sleeve is mounted outside the antenna, its mechanical length is not restricted by the mechanical length of the antenna. It can be charged with dielectric materials of low dielectricity constants. >
TL;DR: In this article, the physical basis of the cold-FET method for extracting parasitic resistances and inductances is examined, and a method to obtain the source resistance from the gate-current dependence of the FET Z parameters is used to analyze FETs with different gate lengths.
Abstract: The physical basis of the cold-FET method for extracting parasitic resistances and inductances is examined. A method to obtain the source resistance from the gate-current dependence of the FET Z parameters is used to analyze FETs with different gate lengths. Inductance results for FETs with different gate widths suggest that inductance extrinsic to the gate fingers is dominant, and models of the gate inductance support this. The effects that possible dependences of the parasitic-FET equivalent-circuit parameters (ECPs) on the gate and drain bias can have on the extracted intrinsic-FET parameters are discussed. >
TL;DR: In this paper, a summary of the results of a mainly experimental investigation into the development of wideband orthomode transducers (OMTs) is presented, showing that satisfactory performance for many applications is possible over bandwidths in excess of 2:1.
Abstract: A summary of the results of a mainly experimental investigation into the development of wideband orthomode transducers (OMTs) is presented. It is shown that satisfactory performance for many applications is possible over bandwidths in excess of 2:1. The wideband return loss and cross-polarization behavior are given where the OMT used is measured in conjunction with a wideband corrugated horn. Two types of OMT are considered: one based on a finline technique and the other on a quad-ridged waveguide geometry. Overall, the latter design gives superior performance. >
TL;DR: In this article, a prototype imaging system for active microwave tomography using cylindrical geometry has been developed, making it possible to obtain images of the dielectric properties of biological targets at 2.45 GHz.
Abstract: A prototype imaging system for active microwave tomography using cylindrical geometry has been developed, making it possible to obtain images of the dielectric properties of biological targets at 2.45 GHz. This configuration allows a fast exploration of body slices placed along the array axis, in a way similar to that of present X-ray scanners. The electromagnetic compatibility (EMC) of this approach is critical because the strongly attenuated received fields are measured on the same array which is being used to emit a high-level illuminating signal. Therefore, carefully designed high-frequency architectures and detection techniques are necessary. The system requires no mechanical movements to illuminate the body from multiple directions (views) and measure the scattered fields. In this way, a complete data set consisting of 64 views is acquired in 3 s using low-power illumination. The system is described, and images obtained with biological phantoms and actual bodies are presented. >
TL;DR: In this paper, the authors analyzed the T junction with an inductive post, taking its diameter into account for the case where the current distribution is assumed on the surface of the post.
Abstract: The authors analyze the T junction with an inductive post, taking its diameter into account for the case where the current distribution is assumed on the surface of the post. A single cylindrical post placed in a T junction improves the impedance matching and compensates the junction discontinuity in a wide frequency band. The effects of the design parameters, such as the diameter of the post and its location, are clarified. The measured return loss is accurately predicted. On the basis of this analysis, an effective design procedure for the T junction is proposed, and the reflection below -30 dB is realized over 4% bandwidth. >
TL;DR: In this paper, the microwave conductivity of a new material, the polymer poly-p-phenylene-benzobis-thiazole (PBT) made conductive by ion-implantation doping with iodine, is measured at 9.89 GHz as a function of temperature using the cavity perturbation technique applicable to thin films of arbitrary shape.
Abstract: The microwave conductivity of a new material, the polymer poly-p-phenylene-benzobis-thiazole (PBT) made conductive by ion-implantation doping with iodine, is measured at 9.89 GHz as a function of temperature using the cavity perturbation technique applicable to thin films of arbitrary shape. The DC and microwave conductivities of PBT are seen to approach asymptotically the low-temperature limit predicted by Mott's energy-dependent hopping model. The potential utilization of conductive polymers in microwave absorbers and electromagnetic interference (EMI) shielding is examined using layered media EM theory. >
TL;DR: In this article, a rapidly convergent algorithm to find the spatial simulated images of a point charge in multilayered media is presented, where the simulated images turn out to be complex; i.e. they have complex amplitudes and are located at complex positions.
Abstract: A rapidly convergent algorithm to find the spatial simulated images of a point charge in multilayered media is presented. The simulated images turn out to be complex; i.e. they have complex amplitudes and are located at complex positions. Surprisingly, these complex images give the static field in multilayered media very accurately (errors approximately 0.1%). The examples of two- and three-layered media are examined, together with the available exact image solutions of singly or doubly infinite series. >
TL;DR: In this article, it is shown that the finite-element method using edge elements succeeds in suppressing spurious solutions and that it succeeds in analyzing three-dimensional electromagnetic waveguide problems in the case of metal wedges.
Abstract: When three-dimensional electromagnetic problems are solved by the finite-element method based on a functional with three components of electric or magnetic field, spurious solutions appear if the traditional tetrahedral elements are used. It is shown in the present work that the finite-element method using edge elements succeeds in suppressing spurious solutions and that it succeeds in analyzing three-dimensional electromagnetic waveguide problems in the case of metal wedges. >
TL;DR: In this article, the authors derived dispersion relations for conventional finite element (FE) and finite-difference (FD) approximations for four versions of the Maxwell equations in the plane: the double-curl equation, the vector Helmholtz equation; the penalty equation; and the primitive, coupled Maxwell curl equations.
Abstract: Dispersion relations are derived for conventional finite-element (FE) and finite-difference (FD) approximations for four versions of the Maxwell equations in the plane: the double-curl equation; the vector Helmholtz equation; the penalty equation; and the primitive, coupled Maxwell curl equations. Comparison with their analytic counterparts reveals the presence and origin of vector parasites. For the double-curl and penalty methods, the dispersion relations are double-valued, admitting an extra, spurious dispersion surface of real-valued wavenumbers. As a result, low wavenumbers support well-resolved and poorly resolved vector parasites. The Helmholtz schemes have monotonic, single-valued dispersion relations for divergence-free physical modes. Specification of divergence-free boundary conditions is sufficient to guarantee the absence of parasites. The primitive schemes have single-valued but folded (nonmonotonic) dispersion relations, supporting poorly resolved vector parasites at low wavenumbers. Use of a staggered finite-difference grid eliminates these parasites and results in a dispersion relation identical to that for the Helmholtz scheme. In cases where vector parasites arise, the same essential weakness in the discretized form of either the first or cross-derivative is responsible. >
TL;DR: In this paper, a systematic method to obtain the bidimensional spectral dyadic Green's function of stratified planar structures with arbitrary complex bianisotropic layers is developed based on the uniqueness and equivalence electromagnetic theorems.
Abstract: A systematic method to obtain the bidimensional spectral dyadic Green's function of stratified planar structures with arbitrary complex bianisotropic layers is developed The method is based on the uniqueness and equivalence electromagnetic theorems A first-order partial differential formulation for the electromagnetic field inside each layer is used An explicit algorithm makes it possible to go from the single-layer formulas to the general multilayer matrix formulation The perturbative nature of the method provides good numerical efficiency and straightforward determination of asymptotic behavior >