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The purpose of this study is to develop and investigate a fast and accurate algorithm for the modeling of characteristic impedance of double-layer coaxial waveguides.

This paper presents the newly developed numerically stable analytical formula for calculation of the characteristic impedance of double-layer coaxial conductor and its elements such as resistance, inductance, capacitance and conductance per unit length. The formula contains modified scaled Bessel functions. The results of the developed analytical formula were compared with results obtained from the axis-symmetric 2D and 3D finite element method (FEM) simulations, using three different solvers.

The proposed method shows a good agreement between results obtained with the new fast and stable analytical model and particular FEM models, selected depending on frequency range. The relative difference between characteristic impedance calculated using the new analytical method and obtained from chosen FEM method for discussed frequency range is less than 0.1 per cent which proves the correctness of the new analytical formula. Noteworthy is the fact that the relative difference of the resistance computed using the developed analytical method and obtained with Maxwell FEM solver for the frequency in range from 1 Hz to 10 MHz is less than 0.01 per cent. The presented work shows that when the calculations are performed over wide frequency range, it is necessary to use more than one solver, especially when the wavelength is comparable with dimensions of the conductor. The computation time of the new analytical model is much shorter than the computation time of FEM.

An efficient, numerically stable algorithm for computation of characteristic impedance of a double-layer coaxial conductor (waveguide).

Gives introductory remarks about chapter 1 of this group of 31 papers, from ISEF 1999 Proceedings, in the methodologies for field analysis, in the electromagnetic community. Observes that computer package implementation theory contributes to clarification. Discusses the areas covered by some of the papers ‐ such as artificial intelligence using fuzzy logic. Includes applications such as permanent magnets and looks at eddy current problems. States the finite element method is currently the most popular method used for field computation. Closes by pointing out the amalgam of topics.

Convergence rates for high‐order finite‐element polynomials are discussed in the context of problems arising in cylindrical co‐ordinate systems with azimuthal symmetry. It is shown that expected rates of convergence can only be obtained by the proper choice of interpolation function.

This paper aims to present the design development and measurement of two aerodynamic slotted X-bands back-to-back planer substrate-integrated rectangular waveguide (SIRWG/SIW) to Microstrip (MS) line transition for satellite and RADAR applications. It facilitates the realization of nonplanar (waveguide-based) circuits into planar form for easy integration with other planar (microstrip) devices, circuits and systems. This paper describes the design of a SIW to microstrip transition. The transition is broadband covering the frequency range of 8–12 GHz. The design and interconnection of microwave components like filters, power dividers, resonators, satellite dishes, sensors, transmitters and transponders are further aided by these transitions. A common planar interconnect is designed with better reflection coefficient/return loss (RL) (S₁₁/S₂₂ ≤ 10 dB), transmission coefficient/insertion loss (IL) (S₁₂/S₂₁: 0–3.0 dB) and ultra-wideband bandwidth on low profile FR-4 substrate for X-band and Ku-band functioning to interconnect modern era MIC/MMIC circuits, components and devices.

Two series of metal via (6 via/row) have been used so that all surface current and electric field vectors are confined within the metallic via-wall in SIW length. Introduced aerodynamic slots in tapered portions achieve excellent impedance matching and tapered junctions with SIW are mitered for fine tuning to achieve minimum reflections and improved transmissions at X-band center frequency.

Using this method, the measured IL and RLs are found in concord with simulated results in full X-band (8.22–12.4 GHz). RLC T-equivalent and p-equivalent electrical circuits of the proposed design are presented at the end.

The measurement of the prototype has been carried out by an available low-cost X-band microwave bench and with a Keysight E4416A power meter in the microwave laboratory.

The transition is fabricated on FR-4 substrate with compact size 14 mm × 21.35 mm × 1.6 mm and hence economical with IL lie within limits 0.6–1 dB and RL is lower than −10 dB in bandwidth 7.05–17.10 GHz. Because of such outstanding fractional bandwidth (FBW: 100.5%), the transition could also be useful for Ku-band with IL close to 1.6 dB.

The assessing of the specific absorption rate (SAR) of living organisms or phantoms is difficult to realize and this paper seeks to do this. SAR much more precisely describes the energy absorbed by biological objects than values of electric field strength (E [V/m]) or power density (S [W/m²]) measured at the point of exposition. However, for living objects the assessing of SAR is not an easy task by measuring methods or even in calculation evaluations. Numerical techniques, especially the finite‐difference time‐domain method (FDTD), offer different possibilities of calculations. The important problem with FDTD method introduced to lossy objects with complex shapes is that this method is not verified with the measuring data.

In this work the results of calculations and measuring data of ellipsoidal phantoms filled with specimen of electrical parameters like muscle tissue are presented. The calculations of SAR have been realized for two cases, e.g. for plane wave incident and for waveguide condition. Measurements for verifying the obtained data were done by waveguide method. The comparison of numerical (the package CONCERTO (Vector Fields Ltd)) and measurement methods were done at frequencies 900 and 1,800 MHz.

Calculations of SAR of lossy objects by FDTD method have been confirmed by measurements and analytical method of calculations. This documents that the package CONCERTO (Vector Fields Ltd) (Concerto User Guide) can be used for such calculations.

This paper presents the results of calculations of SAR of ellipsoidal phantoms filled with specimens of electrical parameters of equivalent muscle tissue.

The principle of microwave characterization of dielectric materials using open-ended coaxial line probe is to link the dielectric properties of the sample under test to the measurements of the probe admittance (Y(f) = G(f)+ jB(f )). The purpose of this paper is to develop an alternative inversion tool able to predict the evolution of the complex permittivity (ε = ε′ – jε″) on a broad band frequency (f from 1 MHz to 1.8 GHz).

The inverse problem is solved using adaptive network based fuzzy inference system (ANFIS) which needs the creation of a database for its learning. Unfortunately, train ANFIS using f, G and B as inputs has given unsatisfying results. Therefore, an inputs selection procedure is used to select the three optimal inputs from new inputs, created mathematically from original ones, using the Jang method.

Inversion results of measurements give, after training, in real time the complex permittivity of solid and liquid samples with a very good accuracy which prove the applicability of ANFIS to solve inverse problems in microwave characterization.

The originality of this paper consists on the use of ANFIS with input selection procedure based on the Jang method to solve the inverse problem where the three optimal inputs are selected from 26 new inputs created mathematically from original ones (f, G and B).

A review of the dielectric measurement techniques that are currently available for the characterization of thick film and LTCC materials at microwave and millimeter wave frequencies is presented. The intention is to show the relative advantages and limitations of the various methods, and to provide some practical guide to the particular technique that is most suitable for a given type of material, for use in a particular application. In addition, a novel slit cavity resonator method is proposed to enable substrate parameters to be more easily measured, whilst retaining high measurement accuracy. Measured data on materials from a variety of manufacturers are presented to show the validity and usefulness of this method.

The dielectric properties of materials (complex permittivity) can be deduced from the admittance measured at the discontinuity plane of a coaxial open‐ended probe. This implies the implementation of an inversion procedure. The purpose of this paper is to develop a new non‐iterative inversion methodology in the field of microwave characterization allowing reducing the computation cost comparatively to iterative procedures.

The inversion methodology combines the support vector machine (SVM) technique and the finite element method (FEM). The SVM are used as inverse models. They show good approximation and generalization capabilities. FEM allows the generation of the data sets required by the SVM parameter adjustment. A data set is constituted of input (complex admittance and frequency) and output (complex permittivity) pairs.

The results show the applicability of SVM to solve microwave inverse problems instead of using traditional iterative inversion methods which can be very time‐consuming. The experimental results demonstrate the accuracy which can be provided by the SVM technique.

The paper allows extending the capability of microwave characterization cells developed at Laboratoire de Génie Électrique de Paris.

A new inversion method is developed and applied to microwave characterization. This new concept introduces SVM in the context of microwave characterization. SVM results and iterative inversion procedure results are compared in order to evaluate the effectiveness of the developed technique.

To outline different versions of a novel method for accurate and efficient determining the dielectric properties of arbitrarily shaped materials.

Complex permittivity is found using an artificial neural network procedure designed to control a 3D FDTD computation of S‐parameters and to process their measurements. Network architectures are based on multilayer perceptron and radial basis function nets. The one‐port solution deals with the simulated and measured frequency responses of the reflection coefficient while the two‐port approach exploits the real and imaginary parts of the reflection and transmission coefficients at the frequency of interest.

High accuracy of permittivity reconstruction is demonstrated by numerical and experimental testing for dielectric samples of different configuration.

Dielectric constant and the loss factor of the studied material should be within the ranges of corresponding parameters associated with the database used for the network training. The computer model must be highly adequate to the employed experimental fixture.

The method is cavity‐independent and applicable to the sample/fixture of arbitrary configuration provided that the geometry is adequately represented in the model. The two‐port version is capable of handling frequency‐dependent media parameters. For materials which can take some predefined form computational cost of the method is very insignificant.

A full‐wave 3D FDTD modeling tool and the controlling neural network procedure involved in the proposed approach allow for much flexibility in practical implementation of the method.

With the drastically changed pattern of the retail food trade in recent years in which the retailer's role has become little more than that of a provider of shelves for commodities, processed, prepared, packed and weighed by manufacturers, the defence afforded by the provisions of Section 113, Food and Drugs Act, 1955 has really come into its own. Nowadays it is undoubtedly the most commonly pleaded statutory defence. Because this pattern of trade would seem to offer scope for the use of the warranty defence (Sect. 115) in food prosecutions it is a little strange that this defence is not used more often.