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A design for manufacturing (DFM) of a well‐performing wideband coaxial filter line using direct metal laser sintering (DMLS) additive manufacturing is proposed. The demonstrated transmission line is an air‐filled coaxial line chosen for low loss and consistent group delay over the bandwidth. Transmission line theory is used first to account for the impact of the shorted stub needed to support the central conductor. Deviations due to parasitics are described to transition the design from an ideal model to a physical prototype. The constraints inherent in DMLS are discussed and accounted for throughout the DFM. This process is demonstrated with a prototype having return and insertion losses of greater than 10 dB and less than 1.64 dB, respectively, over a 5.3:1 bandwidth from 6.4 to 33.9 GHz with a flat group delay of 129 ps ± 7%. [ABSTRACT FROM AUTHOR]

Current physics is considered to be based on Newtonian mechanics. The existence of electromagnetic waves was demonstrated by the Maxwell equations. It is also possible to assume that the constitution of electromagnetic waves forms the fundamental principles of physics, including the composition of materials. To demonstrate this assumption, we introduced electromagnetic waves in coaxial cables and determined the propagation constant of these waves, as reported in this Session. The result showed that the real part of the propagation constant, known as the attenuation constant, can be set to zero. In this case, by expressing the variable of the electromagnetic waves as angular frequency («), it is possible to treat the variable of the function as an angle (in radians). As a consequence, we are able to introduce a mathematical representation of phase (neighborhood and metric) for electromagnetic waves. Thus, we demonstrate that the mathematical representation of electromagnetic waves is possible. [ABSTRACT FROM AUTHOR]

The empirical frequency variations of the complex dielectric permittivity of Rimamid 200, Ultem PEI 1000 and Rexolite 1422 polymer materials in the range from 0.1 to 32 GHz are presented. The feasibility of employing Rimamid 200 as a microwave material is confirmed by examining S-parameters of the in-series PK2-18-01R-01R and PK2-50-05R-05R-05R coaxial adapters having identical beads fabricated from Ultem PEI 1000 and Rimamid 200. A reflection coefficient of smaller than –24 dB and a loss factor of lower than –0.16 dB in the frequency range of 0.01–50 GHz are achieved using the adapters with Rimamid 200 beads. It is noted that Rimamide 200 is a promising material for manufacturing dielectric beads and other elements of microwave equipment. [ABSTRACT FROM AUTHOR]

In this study, we measured the shielding effectiveness (SE) of single-walled carbon nanotubes (SWCNTs), which have attracted interest as potential conductive materials. We studied the preparation of SWCNTs in the form of a film for measurement and the design of coaxial jigs. In addition, coaxial jigs with a maximum operating frequency of 8 GHz were designed and verified to overcome the maximum operating frequency limit of 1.5 GHz in the ASTM D4935 standard. A 3D electromagnetic simulation was used to design the coaxial jigs and a comparative test with the ASTM D4935 standard was performed to verify the proposed measurement jigs. Measurement samples were prepared for each SWCNT powder type, and the SE of the SWCNTs was measured using the proposed measurement jigs. [ABSTRACT FROM AUTHOR]

Heaviside reformulated the Maxwell equations because he considered that electromagnetic fields and waves have duality. As a result of the reformulation, the Poynting vector was obtained. When the variations of an electromagnetic field propagate in space as waves, this wave is referred to as an electromagnetic wave. The Poynting vector represents the traveling direction of the electromagnetic wave. In this Session, we reexamine electromagnetic fields and waves by focusing on the relationship between the Poynting vector and the duality. According to Wikipedia, no current flows in a vacuum because there are no electrons or electric charges. However, this seems to be incorrect, and the current I(x) given by rotH = I(x) flows in a vacuum. Moreover, a voltage V(x) given by rotE = -V(x) is generated because the magnetic field is the dual of the electric field and the current is the dual of the voltage. As a result, the presence of a coil in a vacuum is expressed by rotE = -V (x) = -∂B I ∂t = - pLI (x). Namely, the Maxwell equations indicate that "self-induction can occur everywhere in the atmosphere", as described by Heaviside in the book written by Nahin. Moreover, a capacitor in the atmosphere, including a vacuum, is also given by an equation because it is the dual of the coil. Thus, electromagnetic waves have physical properties of circuit elements including coils and capacitors, which are different from those of lines of forces, such as lines of electric and magnetic forces. The physics of electromagnetic waves is included in classical physics but is different from Newtonian mechanics and uses complex numbers. [ABSTRACT FROM AUTHOR]

In this session, we explain that Heaviside reformulated the Maxwell equations and showed by the vector analysis method that the direction of a flow of power of electromagnetic waves is given by the Poynting vector. Therefore, it was shown that the direction of the flow is perpendicular to the electric and magnetic flux lines. Namely, the direction of the interaction of electromagnetic waves is different from and perpendicular to the directions of the flux lines. Therefore, we examine the arrangement of the electric and magnetic fields of electromagnetic waves. As a result, it is shown that the arrangement of the electric and magnetic fields that form in coaxial transmission lines is highly effective for the transfer and work of electromagnetic waves. [ABSTRACT FROM AUTHOR]

The following study investigates the use of a coaxial transmission line for determining the properties of powdery dielectric materials (1–10 GHz). Four powdery materials with dielectric constants ranging from 3.5 to 70 (SiO2, Al2O3, CeO2, and TiO2) were experimentally investigated at varying volume loading fractions. Powder particles were mixed with a paraffin matrix and properties of the powder were analysed using ten mixing equations to verify their accuracy. These powder‐paraffin composites were also modelled at varying volume loadings for comparison with experimental data to gain a better understanding of the interactions between the different phases. The optimal volume loading fraction was determined to be 10% for all powders tested. A metric for selecting the most well‐suited mixing equation was proposed that involved taking the ratio of the particle dielectric to that of the matrix. This study ultimately provides guidance for experimentally measuring the dielectric properties of unknown powdery materials that have applications for new devices that utilised powder‐based dielectric materials. [ABSTRACT FROM AUTHOR]

Using CST Particle Studio, we simulate the evolution of the multipactor, beginning with a single seed electron inside a coaxial waveguide. Upon impact with either the outer or inner metallic wall, the primary electron is removed and the emitted secondary electrons are allowed to have a realistic 3-D velocity distribution. It is found that the single electron evolves very quickly into an axisymmetric distribution. The radial distribution of the multipactoring electrons is broad and very different from the infinitesimally thin multipactor electron sheet that was often assumed in previous models. The simulated threshold voltage for the onset of multipactor was compared with published experiments, and the level of agreement was found to depend on the secondary electron yield model chosen. [ABSTRACT FROM AUTHOR]

This work presents the results of our studies on the electromagnetic interference shielding effectiveness of small-in-size samples of ferrite composition microwave absorber prepared by using the ceramic method. The shielding effectiveness measurement was performed using the complex intrinsic parameters of the material. The coaxial holder method with the well-known test technique based on transmission/reflection measurements was used in the experimental setup. Complex intrinsic parameters were measured in the frequency range of 2-18 GHz by using the Nicholson-Ross- Weir (NRW) method with an automated test setup. First, the shielding effectiveness was measured by conventional test method and then it was calculated using complex intrinsic parameters with the NRW method. Comparison was made between measured and calculated SEs. By using a new method the SE was determined as a function of the complex intrinsic parameters of materials ϵ , μ, and frequency. This method is preferred in order to provide higher accuracy in determining material electromagnetic shielding effectiveness for small-in-size materials. For the first time, the shielding effectiveness of small-sized samples has been measured in the frequency range between 2 and 18 GHz by using the NRW method. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel approach to broadband model relative effective complex permittivity of soils (augmented broadband complex dielectric mixture model). The approach involves a combination of mixture equation and relaxation model. The mixture equation is an extension in frequency domain developed from a volume average approach. The relaxation model aims at integrating polarization effects that would occur over the frequency range under interest. In this framework, the relative effective complex permittivity is computed from a set of parameters including water saturation, porosity, cementation exponent, and relaxation parameters. The proposed model was tested and validated on a new set of data measured over the 1-MHz–3-GHz frequency range on compacted kaolin. The model was fit to the measured spectra with satisfactory agreement in terms of root-square-mean error. Furthermore, the comparison between estimated and experimentally measured water saturation and porosity has shown a good correlation. This indicates the great potential of this new model for monitoring state parameters for applications in geophysics and geotechnics. [ABSTRACT FROM AUTHOR]

A generator of high-power high-voltage nanosecond pulses is intended for electrical discharge disintegration of mineral quartz and other nonconducting minerals. It includes a 320 kV Marx pulsed voltage generator, a high-voltage glycerin-insulated coaxial peaking capacitor, and an output gas spark switch followed by a load, an electric discharge disintegration chamber. The main parameters of the generator are as follows: a voltage pulse amplitude of up to 300 kV, an output impedance of ≈10 Ω, a discharge current amplitude of up to 25 kA for a half-period of 80-90 ns, and a pulse repetition rate of up to 16 Hz. [ABSTRACT FROM AUTHOR]

This paper proposes an air-gap applied adiabatic line for a coaxial transmission line. The adiabatic characteristics with excellent microwave transmission were simulated in terms of the S-parameter and the heat transfer of coaxial lines with a finite-element-method-based tool for the adiabatic microwave design. The detailed design scheme of the air-gap adiabatic line is presented and its performance is evaluated. The adiabatic efficiency associated with microwave feature was analyzed by a resistive equivalent circuit model of the line. We made a stainless steel air-gap adiabatic line that had about 11 times greater thermal resistance than that of a gapless coaxial line, a beryllium copper line, with the increment of just 0.4-dB insertion loss. We also propose a solution to improve the low-frequency transmission of an air-gap adiabatic line with a tunable ground wire for broad-band feature. [ABSTRACT FROM PUBLISHER]

In this paper, it is found that the coaxial transmission line between the matching box and the plasma reactor plays an important role in impedance matching of atmospheric-pressure radio-frequency capacitively coupled microplasma discharge characterized by very low capacitance value. The high output voltage across reactor terminal is generated when the external circuit is operating in resonant state driven by power supply. The experimental results show that coaxial transmission line exhibits capacitive characteristics within the working frequency range and its capacitance increases linearly with the length of the transmission lines; the resonant frequency and voltage across the terminal reactor decrease with the length of coaxial transmission line. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the electromagnetic shielding effectiveness (EMSE) of thin and lightweight knitted fabrics that are suitable for casual wear like t-shirts. For the purpose of having a low production cost, metal/cotton conductive composite yarns are produced by a yarn doubling technique, involving stainless steel wires (35 μm, 50 μm) or copper wires (50 μm, 70 μm) and Ne30/1, Ne40/1, Ne60/2, Ne80/2 count cotton yarns. Single jersey fabrics are knitted on an E20 circular knitting machine with the same machine settings. Coaxial transmission line and free space measurement (by using an anechoic chamber) techniques are used for the EMSE measurements in the frequency range of 100 MHz–1.5 GHz and 1 GHz–18 GHz respectively. The free space measurement technique test results reveal that single jersey knitted fabrics have EMSE ability for the electric field polarization in the same direction as the main direction of the conductive metal wires in the fabric. It is observed that all single jersey fabric structures have more than 7 dB (80% or better) EMSE for GSM-850 and GSM-900 cellular phone communication bands according to coaxial transmission line equipment test results. SNK test results of both test methods reveal that, while 100% cotton fabrics do not have EMSE ability, cotton yarn count is highly significant on the EMSE of single jersey fabrics with conductive composite yarns. Fabrics with two-ply fine cotton yarns (Ne60/2 and Ne80/2) have higher EMSE values than the fabrics with one-ply cotton yarn of the same yarn count (Ne30/1 and Ne40/1). [ABSTRACT FROM PUBLISHER]

This paper describes the design process of a fast pulse generator, based on a transmission line (TL) system and a spark gap, including its experimental validation. Design criteria and expected parameters are described. Simulation results for the pulse generator obtained with a TL model are presented. This model is implemented using the software package Electromagnetic Transient Program—Alternative Transient program (EMTP-ATP). A constructed pulse generator [based on the mentioned design as well as the simulation results using EMTP-ATP and finite-element method (FEM)] is presented and laboratory test results are described. Simulations and experimental results fit well, except for a difference of 15% in the rise time. The proposed design procedure, which combines TL simulations, theoretical models, and FEM simulations, has been experimentally validated and it can be used to design pulse generator systems for different applications. [ABSTRACT FROM AUTHOR]

This article is a study of an empirical design of an open-ended coaxial cavity resonator. The coaxial cavity resonator can be designed using the coaxial transmission-line theory. It can be done by using the radius of the inner conductor, the inner radius, and the length of the resonator. However, the basic coaxial transmission-line theory can be seen that the characteristics of the resonant frequency and the Q value are varied by the change of length, regardless of the value of radius of the inner conductor and inner radius of the resonator. We find out the impact of radius of the inner conductor, inner radius of the resonator, and the length of the resonator parameter and propose the optimized empirical resonator design method by reducing the error between the theoretical value and the design value. High frequency structure simulator was used for simulation and the material of the resonator was designed with a copper. Based on the simulation, several resonators are fabricated by the size of 14 mm for the radius of inner conductor, 2, 5, and 10 mm, respectively, for the inner radius of resonator, and 8.5 mm for the length of the resonator. The resonant frequencies of the produced resonators were measured at 6.1, 5.7, and 6.5 GHz, respectively. According to the result of simulation and measurement, we know that we can design the relatively exact open-ended coaxial cavity resonator by applying the basic coaxial transmission-line theory directly when the length of the resonator is less than 10 mm, and adding the correction factor of 0.5 GHz to the calculated resonant frequency in case of more than 10 mm of the length of the resonator. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:606-610, 2014 [ABSTRACT FROM AUTHOR]

A molecule dynamics model and details of a large electrical volume coaxial spectrometer are presented in this paper. The molecule dynamics model gives successful molecular signal decay predictions in coaxial spectrometers and shows that our current design is beyond the wall collision limit. The dimensions of the large electrical volume coax and a solution for practical fabrication of the transmission line that avoids spurious mode coupling are also introduced in this paper. The measured spectrum has an 8-dB improvement in signal-to-noise ratio over previous techniques, and fast detection was achieved with 100 averages. The better performance of this coaxial transmission line spectrometer improves its potential in the application of microwave chemical sensing, and the molecule dynamics model is useful for future coaxial spectrometer designs for higher operation frequency where molecular signals are stronger. [ABSTRACT FROM AUTHOR]

We present the measurements performed with a custom coaxial-cage line designed to determine the complex dielectric permittivity of large samples, made of granular and/or liquid materials. The open structure of the cage facilitates the filling of the line, and allows the uniform compactness of the granular materials having large grain size. The electromagnetic parameters of the samples are retrieved using the line scattering coefficients (S-parameters), measured with a vector network analyzer in the frequency range 1 MHz to 3 GHz. The measurements are carried out on water, ethanol, and glass beads using the Boughriet method, which, for non magnetic materials, optimizes the Nicolson–Ross–Weir algorithm. The results confirm that such a device accurately estimates the material complex permittivity in a wide frequency band. However, at very low frequencies and at frequencies multiple of the line half-wavelength resonances, the accuracy significantly reduces. In particular, the accuracy gets worse for materials with high permittivity and low losses. Nevertheless, for natural geo-materials, usually characterized by appreciable losses, the coaxial-cage line can effectively be used to accurately estimate the material electromagnetic properties in a wide frequency band. [ABSTRACT FROM PUBLISHER]

In this article, we present a study dealing with the design, optimization, and manufacturing of different versions of a broadband monopole antenna with a convex conical reflector. These antennas are created by a wire monopole that is placed into the axis of a convex conical reflector. The principle of antennas is based on the transformation of the impedance of a coaxial transmission line to the open space impedance via a circular waveguide. The results of simulations performed in CST Microwave Studio are mutually compared. Then, the simulated versions of broadband monopole antennas were optimized with respect to specified objectives. According the available materials, we built selected versions of the antenna and experimentally verified their properties. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1243-1247, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27598 [ABSTRACT FROM AUTHOR]

In this article, we present a very simple toolkit for permittivity and permeability measurement in the microwave region in real time. This kit contains a coaxial cell and a dedicated software compatible with any Vector Network Analyzer (VNA) for the reconstruction of permittivity and permeability data. The customizing design of the coaxial cell depends on the applications and material forms. The dedicated software for overall cells reconstructs directly in real time the permittivity and the permeability from the S-parameters measured. The Nicolson & Ross-Weir algorithm is using after a de-embedding process done by modeling our cell with an identity card (IC). The novelty of our method is that, after calibration process of the VNA to remove the cable effect, the measurement of the permittivity and permeability were done directly after only one measurement in real time. To validate the accuracy of this new measurement process for new applications, we reconstruct the permittivity of two material forms (dielectric or/and magnetic solids, semisolid). This new toolkit is called EpsiMu (www.epsimu.fr). © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2643-2648, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25570 [ABSTRACT FROM AUTHOR]

Air-filled copper Ka-band resonators with heights between 250–700 μm are demonstrated with measured un-loaded Q factors between 440–829. The low-profile quasi-planar resonators are fabricated using a sequential metal deposition process. Miniaturization of up to 70% with respect to a TE101 quasi-planar resonator is accomplished by reducing the footprint of the resonator while maintaining the height. Finite-element simulations predict the measured resonant frequency within less than 1%. Due to fabrication imperfections, Qun is measured to be approximately 15% less than predicted. The resonators are compatible with air-filled rectangular microcoaxial feed lines fabricated in the same metal-deposition process. [ABSTRACT FROM AUTHOR]

Several low-profile 250-mum-high Ka-band cavity resonators are demonstrated with resonant frequencies near 26 GHz and unloaded quality (Q) factors greater than 400. The air-filled copper cavity resonators are fabricated on a silicon substrate using a photolithographic process. A microrectangular coaxial transmission-line feed is integrated in the same process. Four resonators with different mechanical support structures are demonstrated. The resonators are designed using the finite-element method and simulation of both the resonant frequency and Q factor agree well with measurements [ABSTRACT FROM PUBLISHER]

In this paper, we present a tool for permittivity re-construction. The tool consists of a coaxial transmission line and a novel analytical reconstruction technique. The line is designed for accurate permittivity measurements of soil samples. It allows for single or double phase flow. The full S-parameter matrix is modeled with transmission line theory. We show that for accurate measurements each component of the tool needs careful calibration. We give a method to compute the sensitivity of these measurements to different materials, and we show the accuracy in the determination of the sample permittivity from the measurements based on deviations of the forward model compared to measured results as a function of the error in the sample permittivity. We demonstrate that a maximum error of less than 1% is obtained for the possible permittivity reconstruction from these measurements for wavelengths less than five times the sample holder length. The novel reconstruction technique is based in the propagation matrices method. It consists in rewriting the transmission line model in matrix notation and relating the S-parameters to the total reflection and transmission of the line seen as a two-port network. Thanks to this novel approach, the reconstruction of both permittivity and permeability can be done directly from the measured S-parameters of the line. Due to experimental instabilities the errors are considerable, and we must restrict ourselves to the reconstruction of permittivity. Results on an air sample are within the predicted error of 1%. Computing relative errors for an ethanol sample is not possible due to temperature and purity difference between our experiment and published results; nevertheless, the reconstructed permittivity of ethanol follows the Debye model. [ABSTRACT FROM AUTHOR]

The main goal of this letter is the analysis of the multipactor effect within a coaxial waveguide structure when an external axial dc magnetic field is applied. We have designed and manufactured a coaxial waveguide sample that has been immersed within a long solenoid. Numerical and experimental results confirm a significant change in the RF breakdown behavior with regard to the case without the axial dc magnetic field, as well as the existence of single- and double-surface multipactor regimes. Good agreement between theory and experimental data has been found. [ABSTRACT FROM PUBLISHER]

In this article, we propose a new method to measure the complex relative permittivity (ℇr = ℇr′ - jℇr″) and permeability (μr = μr′ - jμr″) of liquid- or powder-type materials using a two-port probe which is constructed from coaxial transmission lines. The two-port probe is a simple structure that can be easily fabricated with low cost in comparison with conventional probes which are the type of the cavity and waveguide. And we have adopted the Cole–Cole equation and air-filled coaxial cable for calibrating the proposed probe. To verify the performance of the proposed probe, we measured the properties of materials in the form of liquids and powders and compared the results with those measured by the air-filled coaxial cable, which shows good agreement. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2977–2979, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24793 [ABSTRACT FROM AUTHOR]