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A ring resonator used to study the effective permittivity and the loss of substrate integrated suspended line (SISL) is presented in this article. The effective permittivity is obtained by calculating resonant frequency and the relative value of loss is calculated by comparing unloaded quality factor (Q factor). For the four cases of uniform ring resonators, their S‐parameter, effective permittivity, unloaded Q factors are simulated, measured and investigated. The effect caused by the height of air cavity, the material of dielectric substrate, dielectric loss tangent is also investigated. Finally, the calculated results indicate that the effective permittivity of SISL structure at operating frequency is very closed to 1, which manifests that within a certain substrate‐material range the relative permittivity of substrate has little influence on SISL platform that is instructive for SISL circuits design. And the use of metalized via‐hole connection with dielectric removal can reduce the circuit loss dramatically. [ABSTRACT FROM AUTHOR]

ABSTRACT This letter describes a size-independent effective permittivity of biological tissues, using microstrip ring resonator (MRR), to evaluate the moisture content more effectively. As permittivity is depends on material density, the optimum sample size where further size variations will not change the effective permittivity are identified. Using simulation and experimental results it is found that, a sample having thickness more than 9% of substrate height (tsub) and width greater than 18.3% of guided wavelength (λg) shows size-independent effective permittivity. Both simulation and experimental results are in good agreement (within 3%). These findings allow more effective characterization of muscles according to their moisture content. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:4-9, 2016 [ABSTRACT FROM AUTHOR]

In this work, computer-aided design models based on adaptive-network-based fuzzy inference system (ANFIS) for the quasistatic analysis of three different coplanar strip line structures are presented. These strip line structures are conventional coplanar strip lines, asymmetrical coplanar strip lines with infinitely wide strip, and asymmetrical coplanar strip lines with infinitely thick dielectric substrate. The design parameters of the proposed ANFIS models are optimally determined by using four different optimization algorithms, hybrid learning, simulated annealing, least-squares, and genetic algorithm. When the performances of ANFIS models are compared with each other, the best results for training and test are obtained from the models trained with hybrid learning algorithm. There is a good agreement among the results of ANFIS models, quasistatic analysis, a full-wave electromagnetic simulator IE3D, and experimental works realized in this study. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1990–1996, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25372 [ABSTRACT FROM AUTHOR]

We examine the accuracy of metamaterial effective parameters extraction from the reflection and transmission data and show that this procedure could lead to significant errors in the effective permittivity and permeability values near frequencies where the reflection coefficient has low magnitudes, while the refractive index can still be accurately extracted. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1013–1017, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24267 [ABSTRACT FROM AUTHOR]

A method based on adaptive-network-based fuzzy inference system (ANFIS) is presented for the quasi-static analysis of conductor-backed coplanar waveguides. The ANFIS is a class of adaptive networks which are functionally equivalent to fuzzy inference systems. Four optimization algorithms, hybrid learning, genetic, simulated annealing, and least-squares, are used to determine optimally the design parameters of the ANFIS. The results of ANFIS are compared with the results of experimental works, quasi-static and full-wave spectral domain approaches, conformal mapping technique, and a commercial electromagnetic simulator IE3D. The results of ANFIS models are in very good agreement with the results of other methods and experimental works. When the performances of ANFIS models are compared with each other, the best result is obtained from the ANFIS model trained by the hybrid learning algorithm. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 439–445, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24059 [ABSTRACT FROM AUTHOR]

This article presents a new method based on adaptive neuro-fuzzy inference system (ANFIS) to calculate the effective permittivities and characteristic impedances of microstrip lines. The ANFIS is a fuzzy inference system (FIS) implemented in the framework of an adaptive fuzzy neural network. It has the advantages of expert knowledge of FISs and learning capability of artificial neural networks. A hybrid learning algorithm, which combines the least square method and the back propagation algorithm, is used to identify the parameters of ANFIS. The results of ANFIS are compared with the results of the experimental works, quasi-static methods, and a commercial electromagnetic simulator IE3D. There is very good agreement among the results of ANFIS models and quasi-static methods, IE3D, and experimental works. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1191–1196, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23322 [ABSTRACT FROM AUTHOR]

The rigorous second-order accurate finite-difference time-domain method equations at dielectric interfaces are straightforwardly derived though the discretization of the integral forms of Maxwell's curl equations on the nonuniform Yee's lattice and Taylor series extending of continuous field components over finite volumes including the interfaces. It is shown that to obtain second-order accuracy, we not only require to construct proper effective permittivities in the grids containing the dielectric interfaces, but also to choose nonuniform Yee's grids available in the vicinity of the interface. The attempts in the past are not appropriate for this purpose based on the uniform Yee's lattice. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 3007–3011, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22912 [ABSTRACT FROM AUTHOR]

In this article, a design of Lüneberg lens with slices made from low loss dielectric material with hemispherical air-holes drilled appropriately on the top and bottom surface of each of them is presented. A formula to estimate the values of radial dependent effective dielectric constant of air-holes dielectric composite material is suggested. The estimated values are compared with the ones calculated from finite difference time domain method electromagnetic simulations of a periodic lattice of spherical and cylindrical air-holes embedded in a dielectric slab using Nicolson–Ross method. Calculation of S-parameters and near field of lens with hemispherical air-holes under an incident plane wave, using estimated effective constants by the suggested formula are compared with ones using precise theoretical values of dielectric constants. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2332–2337, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22751 [ABSTRACT FROM AUTHOR]

Neural models based on the artificial neural networks (ANNs) for computing the effective permittivities and characteristic impedances of V-shaped conductor-backed coplanar waveguides are presented. The proposed neural models can also be used for calculating the characteristic parameters of conductor-backed coplanar waveguides. Six learning algorithms, Levenberg–Marquardt, bayesian regularization, quasi–Newton, scaled conjugate gradient, conjugate gradient of Fletcher-Reeves, and resilient propagation, are used to train the ANNs. The neural results are in very good agreement with the results available in the literature. When the performances of neural models are compared with each other, the best result is obtained from the ANNs trained by the LM algorithm. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1294–1299, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22473 [ABSTRACT FROM AUTHOR]

This paper presents new and simple models based on artificial neural networks (ANNs) to determine the effective permittivities of suspended microstrip (SM) and inverted microstrip (IM) lines. The neural results are in very good agreement with the theoretical and experimental results available in the literature for both SM and IM lines. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 39: 383–389, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11225 [ABSTRACT FROM AUTHOR]

The dispersion characteristics of the dominant mode in V-shaped microstrip lines are investigated using the finite-difference time-domain (FDTD) method. Such V-shaped microstrip lines are assumed to be fabricated on a single-layer isotropic substrate. The hybrid effects of the inclined angle of the metal wall and the permittivity of the filling material on the effective permittivity and characteristic impedance are examined and compared. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 320–323, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11049 [ABSTRACT FROM AUTHOR]

In this Letter artificial media formed by dense arrays of parallel conducting wires are considered. A simple analytical model for the effective permittivity is derived from quasi-static considerations. The result gives a formula for the permittivity in terms of the geometrical parameters and the frequency. The analysis covers lossy and loaded wires as well. The phenomena that lead to negative permittivity values are discussed. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 47–51, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10512 [ABSTRACT FROM AUTHOR]

Employing the strong fluctuation theory for random media, this article presents numerical results for the effective permittivity and conductivity transition for composite material of dense, nonspherical particles. It shows the functional dependence of anisotropic properties of composite material upon the particle shape and fraction. [ABSTRACT FROM AUTHOR]

A new expression has been developed far calculating the effective permittivity of rectangular microstrip antenna elements with various thicknesses of substrates. This technique is original, simple, and easily adaptable to a wide variety of dielectric materials, scalable over wide frequency ranges, and included in a CAD system. The results obtained from this technique confirm those calculated from formulas reported elsewhere. [ABSTRACT FROM AUTHOR]