Periodic Guided-wave Structures Research Articles

A Short–Open Calibration Method for Accurate De-Embedding of 3-D Nonplanar Microstrip Line Structures in Finite-Element Method

This paper presents the numerical short–open calibration (SOC) method in the full-wave finite-element method (FEM) algorithm for accurate de-embedding of equivalent circuit parameters of a variety of 3-D nonplanar periodic guided-wave and discontinuity structures. It holds its attractive features in high efficiency and good accuracy as demonstrated in the method of moments algorithm, and further allows itself to be capable of characterization of 3-D nonplanar structures. By setting the reference plane along each feeding line as the perfect electric and magnetic conductors, i.e., PEC and PMC, the entire error box involved in each feeding line and impressed source can be characterized by using these two calibration standards, namely, short- and open-ended circuits. Formulation of ABCD matrix of this error box is described under the introduction of an impressed voltage at each port. Then, ABCD matrix of the core circuit structure can be effectively de-embedded or extracted. Finally, a few numerical examples are given to demonstrate the efficiency and accuracy of our proposed full-wave 3-D FEM-SOC approach in numerical de-embedding of 3-D nonplaner structures.

Numerical Modeling and De-Embedding of Non-Planar Periodic Guided-Wave Structures via Short-Open Calibration in 3-D FEM Algorithm

In this paper, a numerical short-open calibration (SOC) technique is presented to numerically model and de-embed a variety of non-planar periodic guided-wave structures based on the 3-D full-wave finite element method (FEM). A simple current source or lumped-port model is introduced in formulation of a determinant FEM algorithm. By incorporating the SOC in the FEM solver, the intrinsic port discontinuity caused by this port model is then fully removed or calibrated out of the core non-planar periodic guided-wave structure during the calibration process. Because of the 3-D nature of FEM, the effective per-unit-length parameters of the core periodic guided-wave structure, i.e., effective propagation constant and effective characteristic impedance, are extracted successfully. Two numerical examples, including microstrip line with periodical loading of shorting pins and metal–insulator–metal composite right/left handed structure, are numerically modeled for demonstration and verification. Extracted results have validated the feasibility and accuracy of the presented FEM-SOC, thereby exhibiting its advanced capability in numerical modeling and de-embedding of non-planar structures with complicated configurations.

FDFD Method Based on Refined Shift-and-Invert Arnoldi Technique for Periodic Leaky-Wave Antennas

The finite difference frequency domain (FDFD) method can be used to analyze the properties of arbitrary complex close/open periodic guided-wave structures. For the open problem, it probably results in a large scale nonsymmetrical generalized eigenvalue problem. In the analysis of the leaky-wave antennas, because the leakage constant (attenuation constant) increases a lot in the working frequency range, the extraction process of the eigenvalues (complex propagation constants) is difficult to converge when the shift-and-invert Arnoldi technique is used to resolve this large scale nonsymmetrical generalized eigenvalue problem. In this paper, a refined shift-and-invert Arnoldi algorithm is adopted to speed the convergence rate by using refined Ritz vectors to approximate the desired eigenvectors. Since the refined method always converges, a simple FDFD method with six field components can be used. The difference equations of this method are much simpler than those of the previous method because the longitudinal field components don't have to be eliminated in order to approximately transform the generalized eigenvalue problem to a standard eigenvalue problem. Consequently, the accuracy of the method can be improved and the boundary conditions can be implemented easily.

Periodic Leaky-Wave Antenna for Millimeter Wave Applications Based on Substrate Integrated Waveguide

Substrate integrated waveguides (SIW) are built up of periodically arranged metallic via-holes or via-slots. The leakage loss of SIW structures increases with the distance between the via-holes or via-slots. An open periodic waveguide with a large via distance supports the propagation of leaky-wave modes and can thus be used for the design of a leaky-wave antenna. In this paper, this leakage loss is studied in detail and used to design a periodic leaky-wave antenna. The proposed concept represents an excellent choice for applications in the millimeter-wave band. Due to its versatility, the finite difference frequency domain method for periodic guided-wave or leaky-wave structures is used to analyze the characteristics of the proposed periodic leaky-wave antenna. Two modes (TE10 and TE20) are investigated and their different leaky-wave properties are analyzed. Based on the proposed leaky-mode analysis method, a novel periodic leaky-wave antenna at 28-34 GHz is designed and fabricated.

Parameter extraction of interdigital slow-wave coplanar waveguide circuits using finite difference frequency domain algorithm

The slow wave effect can be obtained by a capacitively loaded structure with a symmetrical interdigital line connected on both sides of the coplanar waveguide (CPW) central line. The ferroelectric thin film with high dielectric constant can reduce the size of circuit and make it possible to realize tunable devices such as filter by applying voltage on it. Actually, this kind of slow wave structure is a periodic guided-wave structure and can be analyzed by using classic finite difference frequency domain (FDFD) method for periodic guided-wave structures. However, the very compact slow-wave structures will usually result in simulation errors when the classic FDFD method is adopted, which will lead to a nonsymmetrical generalized eigenvalue problem. In this article, the shift-and-invert (SI) Arnoldi method is used to directly resolve this nonsymmetrical generalized eigenvalue problem. As a result, the accuracy of FDFD algorithm is improved. Especially for the large scale eigenvalue problem, SI method can also have a very fast speed of calculation. By means of its complex propagation constant obtained from simulation, one can extract circuit parameters of the interdigital capacitor. Consequently, one can analyze and design relevant resonators and filters in a quick and accurate manner, which are constructed with such interdigital slow wave structures. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.

Finite-Difference Time-Domain Modeling of Periodic Guided-Wave Structures and Its Application to the Analysis of Substrate Integrated Nonradiative Dielectric Waveguide

The finite-difference time-domain (FDTD) method incorporating an equivalent resonant cavity model is presented for the modeling and analysis of guided-wave propagation characteristics of complex periodic structures. By transforming electromagnetic field variables into a new set of periodic variables, which can also be resolved from the Maxwell's equations, one can convert a periodic guided-wave problem into an equivalent resonator problem. Thus, the FDTD method used for a resonant cavity problem can be adopted to simulate periodic guided-wave structures. In addition, the proposed FDTD algorithm can be extended to model lossy periodic propagation problems. In this study, the substrate integrated nonradiative dielectric waveguide, which is a special type of periodic guided-wave structure subject to a potential leakage loss due to its periodic gaps, is investigated as a showcase. The proposed method is first validated and is then used to analyze the guided-wave characteristics of substrate integrated nonradiative dielectric waveguides. It is shown that the substrate integrated nonradiative dielectric waveguide structure, which can easily be fabricated in planar form, has a well-behaved propagation property suitable for high-performance millimeter-wave circuit design.

Equivalent Resonant Cavity Model of Arbitrary Periodic Guided-Wave Structures and Its Application to Finite-Difference Frequency-Domain Algorithm

An equivalent resonant cavity model is proposed and developed for efficiently and accurately extracting the complex propagation constant of any arbitrary bounded and unbounded periodic guided-wave structures, which is known as a difficult eigenvalue problem with respect to a deterministic or S-parameter-based field solver. In this study, this problem is formulated as a standard eigenvalue one, which is made possible by effectively translating the transmission distance-related attenuation part of complex propagation constant into a time-dependent damping factor. This allows the development of an equivalent resonant cavity model to substitute or replace the periodic guided-wave model, leading to a complex frequency simulation model. As a result, the simulation time and storage requirement are then reduced significantly with this complex frequency approach. A finite-difference frequency-domain algorithm combined with this model is used to demonstrate the concept, and the properties of arbitrary complex closed/open periodic guided-wave structures are rigorously investigated. The proposed algorithm has been validated by both simulations and experiments

Versatile bistable gate based on quadratic cascading in a Bragg periodic structure

A periodic guided-wave grating structure, with a Bragg-induced forbidden gap at the fundamental frequency, is numerically investigated in the presence of nonlinear cascading through second-harmonic generation. A variety of nonlinear responses are obtained for this eight-port device, including switching, limiting, and multistability. We illustrate the device’s operating principles and some of its most interesting features, with emphasis on single-frequency input and outputs and also in the presence of a seed at the second harmonic.