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Additively manufactured rectangular waveguides for the electromagnetic characterization of materials using the transmission/reflection line method

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RAPID PROTOTYPING JOURNAL 2024年第2期30卷 270-276页

作者： Smith, Connor Shane Julius, Alanna Arbeeny, Christian Stevens, John Davenport United States Naval Acad Dept Elect & Comp Engn Annapolis MD 21402 USA

PurposeRadio frequency (RF) technology relies on the electromagnetic properties of the materials used, which includes their complex permittivities and loss tangents. To measure these properties, techniques for material characterization such as the transmission/reflection method are used in conjunction with conversion techniques to calculate these values from scattering parameters. Unfortunately, these techniques rely on relatively expensive rectangular waveguide adaptors and components, especially if testing over large frequency ranges. This paper aims to overcome this challenge by developing a more affordable test equipment solution based on additively manufactured waveguide ***/methodology/approachTo evaluate the effectiveness of using additively manufactured waveguides to perform electromagnetic characterization with the transmission/reflection method, samples of PLA Tough with varying infill percentages and samples made from several Formlabs photopolymer resins are fabricated and *** show that the method yielded permittivity and loss tangent values for the measured materials that generally agree with those found in the literature, supporting its ***/valueThe accessibility of this measurement technique will ideally allow for more electromagnetic material characterization to occur and expand the possible use of additive manufacturing in future RF designs. This work also provides characterization of several Formlabs photopolymer resins, which have not been widely analyzed in the current literature.

关键词： Additive manufacturing rectangular waveguides Electromagnetic materials

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CAD-oriented equivalent circuit modeling of step discontinuities in rectangular waveguides

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IEEE MICROWAVE AND GUIDED WAVE LETTERS 1996年第4期6卷 171-173页

作者： Weisshaar, A Mongiardo, M Tripathi, VK Department of Electrical and Computer Engineering Oregon State University Corvallis OR USA Istituto di Elettronica Universiti di Perugia Perugia Italy

A novel equivalent circuit model for step discontinuities in rectangular waveguides is presented, The equivalent circuit model is based on a modal analysis and enables full-wave characterization of the step-discontinuity by circuit analysis on commercial simulators, The equivalent circuit model of the H-plane step has been implemented on Libra to demonstrate its accuracy. Results of the circuit analysis were found to be in virtually perfect agreement with the conventional mode-matching solution based on incident and reflected wave amplitudes.

关键词： Equivalent circuits rectangular waveguides Waveguide discontinuities Modal analysis Circuit analysis Transmission line matrix methods Voltage Circuit simulation Magnetic fields Convergence

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Near-field microwave model of multilayered structures illuminated by open-ended rectangular waveguides

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IET MICROWAVES ANTENNAS & PROPAGATION 2012年第1期6卷 100-107页

作者： Jundi, A. J. Qaddoumi, N. N. Amer Univ Sharjah Dept Elect Engn Sharjah U Arab Emirates

Near-field microwave non-destructive evaluation and inspection of structures and materials is widely used in various applications. Single-frequency measurements were found to be effective in detecting defects and abrupt changes, such as cracks and air voids, within homogeneous structures. However, in some complex structures with many variables, multiple-frequency measurements were utilised to solve problems associated with more unknown parameters. Those problems involved layered structures with more diversity in terms of number of factors that define the structure, namely, the thicknesses and relative complex permittivities (epsilon(r)) of the layers. Later on, more systematic broadband techniques, such as frequency-modulated continuous wave, proved to be effective in measuring thicknesses of layers in a multilayered structure. However, obtaining permittivity information was still a big challenge. This study presents a novel analytical near-field model that relates the radiation of a rectangular waveguide with the reflection when applied to a dielectric multilayered structure. The input-output relation is characterised by the frequency response of the structure which was analytically derived. As a side result the distribution of the reflection coefficient over the aperture was also analysed and the expression was derived. The main goal is to define the relationship between the structure layers, in terms of thicknesses and relative permittivities and the aperture's complex reflection coefficient (Gamma) for all frequencies of operation. This model can be used in developing new microwave non-destructive evaluation techniques for inspecting the integrity of layered structures with potentially high resolution.

关键词： single-frequency measurements Dielectric materials and properties permittivity aperture-S complex reflection coefficient waveguides and microwave transmission lines homogeneous structures open-ended rectangular waveguides systematic broadband techniques relative complex permittivity frequency-modulated continuous wave rectangular waveguides frequency response multilayered structure inspection near-field microwave model air voids multilayers variable multiple-frequency measurements microwave nondestructive evaluation techniques dielectric multilayered structure

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Dyadic Green's Function of Perfect Electromagnetic Conductor rectangular waveguides and Cavities

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IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION 2023年第1期71卷 902-909页

作者： Sahafi, Seyyed Abbas Ghaffari-Miab, Mohsen Tarbiat Modares Univ Dept Elect & Comp Engn Tehran 13116 Iran

In this article, we present the dyadic Green's functions (DGFs) for electric dipole excitation of perfect electromagnetic conductor (PEMC) rectangular waveguides and cavities. To derive the DGFs of a PEMC rectangular waveguide, we define two sets of orthogonal vector wave functions, that satisfy the boundary conditions at the waveguide walls. The theory of finding the DGF of this waveguide is based on the Ohm-Rayleigh method and orthogonal properties of the rectangular vector wave functions. By having the DGFs of this waveguide, one can derive the DGFs of a PEMC rectangular cavity using the scattering superposition (SSP) principle. The derived electric DGF of this waveguide is used to obtain the electric field propagated inside the waveguide due to an arbitrary current distribution. The distribution of the electric field inside the PEC, PMC, and PEMC waveguides will be obtained and compared with each other.

关键词： Manganese rectangular waveguides Electromagnetic waveguides Boundary conditions Wave functions Electromagnetic scattering Electromagnetics Dyadic Green's function (DGF) Ohm-Rayleigh method perfect electromagnetic conductor (PEMC) rectangular cavity rectangular waveguide

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Analysis of rectangular waveguides and thick windows as EMI sensors - Abstract

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JOURNAL OF ELECTROMAGNETIC WAVES AND APPLICATIONS 1999年第7期13卷 981-982页

作者： Bhattacharya, A Gupta, S Chakraborty, A Indian Inst Technol Dept Elect & Elect Commun Engn Kharagpur 721302 W Bengal India

Open-end of a waveguide or a window backed by a wave-guide can be used as an EMI sensor. A Moment Method analysis of such sensors, illuminated by an uniform plane wave incident from any direction in space is presented. The antenna factor of the sensor i.e., the incident electric field required to generate an input voltage at the measuring port of the sensor, is derived. Numerical and experimental data are presented for open-ended waveguide sensor, thick window sensor and dielectric backed waveguide sensor. The results are also compared with an empirical antenna factor formula used by EMC practitioners. The experimental results show a very good agreement with the theoretically predicted data. (Author abstract)

关键词： Electromagnetic interference rectangular waveguides Sensors

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CHARACTERISTICS OF LOADED rectangular waveguides

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IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES 1965年第4期MT13卷 451-&页

作者： MUSHIAKE, Y ISHIDA, T Department of Electrical Communications Faculty of Engineering University of Tohoku Sendai Japan Department of Electronic Engineering Faculty of Engineering Yamanashi University Kofu Japan

Electromagnetic fields of a rectangular waveguide with an arbitrarily loaded slab are theoretically analyzed. Eigenvalues for the transmission modes are presented in the form of universal eigenvalue charts. Electric field distributions in the loaded waveguide are obtained theoretically, and they are compared with the results of measurements. Power attenuation is also discussed, and attenuation charts that give the lowest limitation for the attenuation are shown. As an example of application the attenuation characteristic of waveguide resistance attenuators are investigated, and a new interpretation is derived for the phenomena where the curves of attenuation characteristic have sharp peak points.

关键词： Loaded waveguides rectangular waveguides Electromagnetic waveguides Attenuation Waveguide theory Eigenvalues and eigenfunctions Electromagnetic fields Slabs Electromagnetic analysis Electrical resistance measurement

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Short-circuit equivalence between rectangular waveguides of regular sidewalls (rectangular waveguide) and sidewalls of cylinders (substrate-integrated rectangular waveguides), plus its extension to cavity

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IET MICROWAVES ANTENNAS & PROPAGATION 2007年第3期1卷 639-644页

作者： Che, W. Xu, L. Wang, D. Deng, K. Chow, Y. L. Nanjing Univ Sci & Technol Dept Elect Engn Nanjing 210094 Peoples R China Univ Waterloo Waterloo ON N2L 3G1 Canada

Substrate-integrated rectangular waveguide (SIW) is a rectangular waveguide (RW) with two sidewalls of cylinders (vias) instead of solid walls connecting the solid wall of the top and bottom plates. An equivalence formula between their widths has been derived based on the work by Che et al., 2005 [2005 Asia-Pacific Microwave Conference, Suzhou, China, December 4-7, 2005, pp. 296-299]. The authors have derived the equivalence formula between the locations of the corresponding short circuits by cylinder walls and by the solid wall. An extension of latter is the equivalence between resonance cavities of SIW and RW. Such equivalences are convenient for the design of small waveguides, of millimeter wave, in a multilayer circuit structure, such as the low-temperature co-fired ceramic. Some numerical simulations and experiments have been carried out to demonstrate the validity of the proposed approaches.

关键词： short-circuit equivalence LTCC cavity resonators low-temperature co-fired ceramic substrate-integrated rectangular waveguides cavity waveguides and microwave transmission lines regular sidewalls rectangular waveguides Waveguide and microwave transmission line components multilayer circuit structure SIW cylinders solid walls millimeter wave

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WAVES AND EVESCENT FIELDS IN rectangular waveguides FILLED WITH A TRANSVERSELY INHOMOGENEOUS DIELECTRIC

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IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES 1970年第10期MT18卷 696-+页

作者： BAIER, W Institute of High-Frequency Techniques Technical University Munich Germany

A numerical-calculation method for rectangular waveguides containing a transversely inhomogeneous dielectric is presented. The method is not restricted to the cutoff case or to special inhomogeneities. The relative permittivity of the dielectric can be an arbitrary function of the cross-sectional coordinates. The electric-and magnetic-field strengths, the dispersion characteristics of the propagating modes, and the attenuation constants of the evanescent modes result from the solution of a matrix eigenvalue problem with typically 8000 matrix elements. Propagating and evanescent modes in a waveguide containing a longitudinal semicircular dielectric rod are calculated as examples. The accuracy of the calculation method is confirmed by measurements and by calculating a special example with an exactly known solution. The error of the field intensities is typically 5 percent; the error of the dispersion characteristics and of the attenuation constants is typically 0.5 percent.

关键词： rectangular waveguides Electromagnetic waveguides Nonuniform electric fields Dispersion Nonhomogeneous media Permittivity Attenuation Transmission line matrix methods Dielectric losses Perturbation methods

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Characterization of complex permittivity properties of materials in rectangular waveguides using a hybrid iterative method

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IEEE MICROWAVE AND GUIDED WAVE LETTERS 2000年第5期10卷 186-188页

作者： Esteban, H Catala-Civera, JM Cogollos, S Boria, VE Univ Politecn Valencia Dept Commun Valencia 46022 Spain

In many microwave applications, an accurate knowledge of the complex permittivity properties of materials is usually required. A new procedure for the accurate determination of these properties is presented, based tn an optimization algorithm that makes use of measured scattering parameters and simulated results of a cylindrical rod of dielectric material passing completely through a rectangular waveguide. The simulation tool employed consists of a very accurate hybrid iterative method, Results for the permittivity properties of ethanol (high-loss liquid material) are presented and validated with results from the literature.

关键词： dielectric materials optimization methods parameter estimation rectangular waveguides spectral domain analysis

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Simple and accurate solutions of the scattering coefficients of E-plane junctions in rectangular waveguides

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IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES 1995年第12期43卷 2716-2718页

作者： Widarta, A Kuwano, S Kokubun, K Department of Electrical Engineenng College of Engineering Nihon University Fukushima Japan Nihon Daigaku Chiyoda-ku Tokyo JP Dept. of Electr. Eng. Nihon Univ. Fukushima Japan

Simple and accurate solution of the scattering coefficients of the E-plane right-angle bend in rectangular waveguide is presented. The solution is obtained by the mode-matching method in which the electromagnetic fields in waveguides are matched with those in junction section formed by a sectoral region. In the same procedure, the solutions of the scattering coefficients of the E-plane T-junction and the cross junction can be also obtained easily. By using the numerical results, the scattering properties of the dominant modes and higher-order modes in the E-plane right-angle bend are examined in detail.

关键词： Electromagnetic waveguides Waveguide junctions Electromagnetic scattering rectangular waveguides Equivalent circuits Mode matching methods Electromagnetic fields Transmission line matrix methods Frequency Waveguide theory

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