Analysis Of Microwave Devices Research Articles

Trends of Microwave Devices Design Based on Artificial Neural Networks: A Review

The usage of techniques of the artificial neural networks (ANNs) in the field of microwave devices has recently increased. The advantages of ANNs in comparison with traditional full-wave methods are that the prediction speed when the traditional time-consuming iterative calculations are not required and also the complex mathematical model of the microwave device is no longer needed. Therefore, the design of microwave device could be repeated many times in real time. However, methods of artificial neural networks still lag behind traditional full-wave methods in terms of accuracy. The prediction accuracy depends on the structure of the selected neural network and also on the obtained dataset for the training of the network. Therefore, the paper presents a systematic review of the implementation of ANNs in the field of the design and analysis of microwave devices. The guidelines for the systematic literature review and the systematic mapping research procedure, as well as the Preferred Report Items for Systematic Reviews and Meta-Analysis statements (PRISMA) are used to conduct literature search and report the results. The goal of the paper is to summarize the application areas of usage of ANNs in the field of microwave devices, the type and structure of the used artificial neural networks, the type and size of the dataset, the interpolation and the augmentation of the training dataset, the training algorithm and training errors and also to discuss the future perspectives of the usage of ANNs in the field of microwave devices.

SIMULATION OF COMPACT POLARIZERS FOR SATELLITE TELECOMMUNICATION SYSTEMS WITH THE ACCOUNT OF THICKNESS OF IRISES

Background. One of the main problems in modern satellite telecommunication systems is to increase the volume of information transmission with simultaneous preservation of its quality. Key element of such systems is antenna systems with polarization processing, which is carried out using polarizers. Therefore, development of new polarizers and simple techniques for their analysis and optimization are important problems. The most simple, effective, technological and actual for analysis are polarizers based on waveguides with irises. Objective. The purpose of the paper is to create a mathematical model of the polarizer based on a square waveguide with irises, which allows analyzing the influence of polarizer’s design parameters on its electromagnetic characteristics. Methods. A mathematical model of the waveguide polarizer with irises is created by decomposition technique using transfer and scattering wave matrices. To take into account the irises’ thickness their equivalent T- and Π-shaped circuits were used. Results. We have developed mathematical model of the waveguide polarizer with irises, which takes into account their thickness and is based on the complete scattering wave matrix of the waveguide polarizer. The matrix has been obtained using the microwave circuit theory. The main characteristics of the waveguide polarizer were defined using matrix elements. The optimization of characteristics of a polarizer was carried out in the operating Ku-band 10.7–12.8 GHz. Conclusions. Suggested mathematical model of a waveguide polarizer with irises provides the account of heights of irises, distances between them and their thickness. The results obtained show that this model is simpler and faster for the calculation of electromagnetic characteristics compared to finite elements method, which is often used for analysis of microwave devices for various applications.

An Efficient Perturbative Approach for Finite-Element Analysis of Microwave Devices Exhibiting Small Geometrical Variations

An innovative method for fast analysis of geometrical variations in electromagnetic wave problems is proposed. The method is based on a perturbative approach applied to the solution of the linear integro-differential operator of the electromagnetic problem in presence of small domain modifications. This approach has been embedded in a classical finite-element framework to achieve a very fast technique for field evaluation in synthesis or tolerance investigation of microwave passive devices. The proposed technique can handle geometrical variations without the need of re-meshing the domain and without any deformation of the original mesh of the problem.

A fast analysis of microwave devices by the combined unifrontal/multifrontal solver for unsymmetric sparse matrices

AbstractThe multifrontal method is applied for solving a large, sparse, and unsymmetric system of linear equations resulting from the use of the edge‐based finite‐element method (FEM). The finite‐element method combined with perfectly matched layers (PML) is given for simulation of microwave devices, and the combined algorithm of the multifrontal method is described. The electrical characteristics of typical waveguide devices such as the ferrite phase shifter and circulator are analyzed, and the calculated results are compared with those obtained from the literature. In order to demonstrate the efficiency of the multifrontal method, the computational time is compared with that of both successive overrelaxation (SOR) preconditioned conjugate‐gradient (PCG) and conjugate‐gradient methods (CG) for the phase shifter. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 76–81, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10521

Hierarchical multilevel potential preconditioner for fast finite-element analysis of microwave devices

A robust hierarchical multilevel preconditioning technique is presented for the fast finite-element analysis of microwave devices. The proposed preconditioner is based on a hierarchical multilevel scheme for the vector-scalar potential finite-element formulation of electromagnetic problems. Numerical experiments from the application of the new preconditioner to the finite-element analysis of microwave devices are used to demonstrate its superior numerical convergence and efficient memory usage.

Hybrid multilevel/multigrid potential preconditioner for fast finite element modeling

A robust hybrid multilevel/multigrid potential preconditioner is introduced for the fast and robust finite-element modeling of electromagnetic structures. The proposed preconditioning process combines the advantages of the hierarchical multilevel preconditioner and the nested multigrid potential preconditioner into a novel preconditioner with superior computational versatility. Numerical experiments from the application of the new preconditioner to the finite-element analysis of microwave devices demonstrate its superior numerical convergence and efficient memory usage.

An Error Estimator for Design Sensitivities of Microwave Device Parameters

A new error estimator for design sensitivities is proposed for finite-element analysis of microwave devices. A function of scattering parameters, C, varies with parameter g. By the adjoint method, the sensitivity dC/dg can be found. A new estimate of the error in dC/dg is based on derivatives of C with respect to position for internal nodes in the mesh (not on any parameterized boundaries or interfaces). It is shown that these estimates of the error are close to the actual errors for a variety of test cases. The estimator is tested using a p-adaptive finite-element method.

Robust multigrid preconditioner for fast finite element modeling of microwave devices

A robust preconditioning technique is presented for the fast finite element modeling of microwave devices. The proposed preconditioner is based on a multigrid scheme for the vector-scalar potential finite element formulation of electromagnetic problems. Numerical experiments from the application of the new preconditioner to the finite element analysis of microwave devices are used to demonstrate its superior numerical convergence and efficient memory usage.

Iterative solvers for hierarchal vector finite element analysis of microwave problems

The finite element analysis of microwave devices reduces to the solution of a large, sparse matrix equation. Several iterative solution methods were tested on the matrices arising when high-order, hierarchical edge elements are used. The best algorithm tested was the conjugate gradient method, with a preconditioner based on symmetric successive overrelaxation. The number of iterations needed was found to increase only slowly with element order for the first three orders, despite the corresponding large increase in the matrix dimension. In all cases there was a rapid deterioration in performance when the element size exceeded about a tenth of a wavelength.

Energy model for optically controlled MESFETs

An energy-based transport model for the analysis of illuminated microwave active devices is presented. The model is based on the Boltzmann's transport equation, with optical carrier generation and carrier recombination accounted for. The simulation results are compared with the conventional local-field mobility models based on drift-diffusion formulations. It is shown that the drift-diffusion models lose their applicability in submicrometer gate-length devices. The presented time-domain model has a great potential in the analysis of microwave devices under ac and pulsed illumination conditions.

Energy model for optically controlled MESFETs

An energy-based transport model for the analysis of illuminated microwave active devices is presented. The model is based on the Boltzmann's transport equation, with optical carrier generation and carrier recombination accounted for. The simulation results are compared with the conventional local-field mobility models based on drift-diffusion formulations. It is shown that the drift-diffusion models lose their applicability in submicrometer gate-length devices. The presented time-domain model has a great potential in the analysis of microwave devices under ac and pulsed illumination conditions. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 26: 48–52, 2000.

A port element for p-adaptive S-parameter calculation

A new element is proposed for the treatment of ports in p-adaptive finite-element analysis of microwave devices. The element consists of a number of segments, on each of which the field is represented by high-order, hierarchical polynomials that match those used in the interior. As the p-adaption proceeds, the number of waveguide modes taken into account on the port increases, and so does the accuracy of the port boundary condition. Results for several H-plane problems in rectangular waveguide demonstrate that, with the new element, adaptive convergence to the same scattering parameters can be achieved no matter how closely the ports are placed.

Analysis of passive microwave devices by using three‐dimensional tangential vector finite elements

AbstractThere are two major difficulties in applying the finite element method to the analysis of microwave devices in three dimensions. One is to obtain a stable vector finite element which does not generate spurious modes, or non‐physical solutions, in the numerical analysis. The other is to model efficiently the coupling of port regions and the discontinuity region. In this paper, we describe the application of two new finite element techniques, the tangential vector finite element method and the transfinite element method, for modelling three‐dimensional microwave devices. The tangential vector finite element method, unlike the conventional nodal finite element methods, imposes only the tangential continuity of the vector unknown across elements' boundaries. As a result, there would be no spurious modes, and reliable solutions are obtained. The transfinite element method, which combines the modal basis functions and the finite element basis functions through the variational technique, provides an efficient way to model the open boundary nature of the device. To validate the current analysis, a low VSWR waveguide connector and two microstrip low‐pass filters are analysed. Numerical results agree very well with the measurements or those obtained by other methods.