Three-dimensional Electromagnetic Field Research Articles

Printable Planar Dielectric Antennas

Thick film screen-printing technology is employed to introduce planar dielectric antennas. The micron-size-thick film is made from high-permittivity dielectric paste, which is printed on a low-loss low-permittivity microwave substrate to operate as a magnetic wall boundary. A simplified theoretical model is developed to analyze the antenna structure. The accuracy of this model is evaluated by the results of a commercial three-dimensional (3-D) electromagnetic field solver. The model works well with less than 5% deviation from time-consuming simulations, providing the permittivity contrast between the film and substrate is kept high (e.g., > 30). The impact of dielectric loss of the film in antenna performance is significantly less than that of the substrate, allowing medium-loss films (e.g., ε"= 3) results in highly efficient antennas with over 95% radiation efficiency. A prototype was made using screen printing and experimentally characterized at Ku-band. The experimental results confirm the theoretical achievements. The measured -10 dB impedance bandwidth of the printable planar dielectric antenna having dimensions of 0.2 λ0× 0.2 λ0 is over 10% with a measured gain ranging from 4.5 to 5.5 dBi. Broadside radiation patterns with cross polarization levels of lower than -20 dB are achieved. This process is compatible with low-temperature cofired ceramic (LTCC) technology where similar idea can be applied to other passive microwave components.

Particle accelerations in two colliding plasma shock waves

A kinetic model of the head-on collision of two magnetized plasma shocks is analyzed theoretically and with numerical calculations. Three-dimensional electromagnetic fields can be modeled as two magnetic fields that intersect at an arbitrary angle; such interaction plays an important role as the asymmetric collision of two shocks. The rate of increase of the attainable energy gain and the aspect ratio of an accelerating test particle are derived from theoretical analysis of the relativistic equations of motion. If the magnetic field has any curvature, a transverse magnetic field is generated that crosses the magnetic reconnection layer. The trajectory of the accelerating particle is bent by this magnetic field, producing the reduction of energy gain as a result.

Design of a sector bowtie nano-rectenna for optical power and infrared detection

We designed a sector bowtie nanoantenna integrated with a rectifier (Au–TiO x –Ti diode) for collecting infrared energy. The optical performance of the metallic bowtie nanoantenna was numerically investigated at infrared frequencies (5–30 μm) using three-dimensional frequency-domain electromagnetic field calculation software based on the finite element method. The simulation results indicate that the resonance wavelength and local field enhancement are greatly affected by the shape and size of the bowtie nanoantenna, as well as the relative permittivity and conductivity of the dielectric layer. The output current of the rectified nano-rectenna is substantially at nanoampere magnitude with an electric field intensity of 1 V/m. Moreover, the power conversion efficiency for devices with three different substrates illustrates that a substrate with a larger refractive index yields a higher efficiency and longer infrared response wavelength. Consequently, the optimized structure can provide theoretical support for the design of novel optical rectennas and fabrication of optoelectronic devices.

Investigation of a circular TE11-TE01-mode converter in stepped waveguide technique

A compact and broadband TE11-TE01-mode converter, suitable for various industrial applications like bypass level measurements, is presented in this contribution. Based on stepped waveguide technique, the main advantages of the recommended converter design and the specific field distribution of the TE01-mode are discussed in detail. The converter is presented exemplary for a frequency range from 23 to 28 GHz, which corresponds to a bandwidth of approximately 20 % of the center frequency. Numerous three-dimensional electromagnetic field simulations are performed to optimize the converter and to investigate its reflection and transmission behavior. Realized by six different single elements and 11 parts in total, fast and effective simulations can be performed with CST Microwave Studio. Considering realistic production process parameters, like fillets or tolerances, a good return loss better 17 dB, an insertion loss of 0.1 dB, and an excellent mode purity are achieved. Compared with back-to-back, realistic disturber scenario, and far-field measurements with a first prototype, the expected excellent converter behavior can be validated without limitations. Hence, the suitability of the presented converter design is proven and the feasibility is demonstrated.

Noise coupling between through-silicon vias and active devices for 20/14-nm technology nodes

Although a through-silicon via (TSV) is widely used in three-dimensional integrated circuit systems, one of its major design challenges is noise coupling between TSVs and active devices. This paper investigates noise coupling between TSVs and active devices for 20/14-nm technology nodes. The effect of variations of structural parameters on noise coupling was examined using a three-dimensional full-wave electromagnetic field solver and its result was explained. Additionally, transient analysis on coupling noise was conducted with Synopsys TCAD. Furthermore, a combined strategy employing doped signal TSVs and ‘bare’ ground TSVs was proposed and compared with conventional signal/ground schemes. Demonstrated to improve noise isolation effectively, the proposed strategy is inherently advantageous to circuits of advanced technology nodes compared with other noise isolation schemes, for it demands no modification of the original circuit design, placement and routing.

On specific features of modeling electromagnetic field in the connection area of side busbar packages to graphitization furnace current leads

This paper describes methods for intensification of the electrical parameters and calculation of the effective cross sections of the end busbars, the current leads of the graphitization furnaces, and the sections of the side busbar packages on the side of an ac graphitization furnace rear end, as well as increasing the energy efficiency of both the furnace equipment and the graphitization electrical system as a whole developed to produce marketable and competitive products. The existing models and calculation methods are inadequate, significantly distort the actual picture of the electromagnetic processes in a complex spatial system of the current leads in a graphitization furnace and the busbar packages of the furnace loop, and do not meet current accuracy standards. In this work, conjugate three-dimensional electromagnetic and thermal fields in the connection area of the side busbar packages to the current leads of an ac graphitization furnace have been numerically simulated by finite element methods and on the basis of the theories of electromagnetic fields and of heat and mass transfer. This paper presents theoretical studies and a simulation of the electromagnetic, electrothermal, and heat-and-mass transfer processes in the connection areas of the side busbar packages to the current leads of the graphitization furnace based on numerical implementation by a finite element method of a generalized 3D model of dc and ac graphitization that considers the temperature dependences of the electrophysical and thermophysical properties of the materials of the busbars and the current leads. A technique for calculation of the effective cross sections of the end busbars according to the equal load criteria has been proposed, which ensures reductions in the weight and the electrical losses in the end busbars. The pattern and regularities of distribution of the current densities and the specific electric losses in the end busbar packages and the current leads of the ac graphitization furnaces have been defined. It has been established that selection of effective cross sections of the end busbar packages based on the criteria of equal loads in terms of the current density and the specific electric losses enables a reduction in the weight by 12% and in the active losses by 15% as compared to the default design, thus enhancing the energy efficiency of the graphitization electrical system. The proposed technique can be applied to both direct action resistance furnaces and high-capacity electric arc furnaces of ac power frequency.

Beampattern analysis of planar frequency diverse array

Compared with conventional phased array, frequency diverse array (FDA) can provide range-angle-dependent beampattern. However, most of reported investigations on this concept focus on linear frequency diverse array, referred as Linear-FDA in this article. Compared with linear array, planar array can provide better directionality and higher gain. In this article, we focus on the beampattern characteristic analysis of planar frequency diverse array (Planar-FDA) and study the auto-scanning feature of its beampattern. The variation of the mainbeam with respect to time is analyzed and the constraint to guarantee the auto-scanning characteristic of the beampattern is derived. The signal transmitted from each element is designed under the constraint and the radiation characteristics of the beampattern of Planar-FDA are examined via three-dimensional electromagnetic field simulation software. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:436–444, 2015.

Influence of Underexcitation Operation on Electromagnetic Loss in the End Metal Parts and Stator Step Packets of a Turbogenerator

The leading operation of large generators is an effective method to adjust the electric reactive power surplus, and the leading-power factor was restricted by the temperature rise of the end parts. In this paper, a three-dimensional (3-D) electromagnetic field of a 330-MW water-hydrogen-hydrogen-cooled turbogenerator in the end region was investigated, and the effect of end leakage magnetic flux on stator step packets was considered in the calculation process. The magnetic flux density distribution was analyzed, and the eddy current losses of metal parts in the end region and core losses of stator step packets were calculated under lagging and leading operations. The influences of the leading-power factor on the losses of end components were analyzed, which could provide a theoretical basis for the safety of the leading operation.

Electrical Characterization on Signal Transmission of SATA Cable Assembly

Signal transmission analysis is performed for a serial advanced technology attachment (SATA) cable assembly using a three-dimensional (3D) electromagnetic field simulation. In this work, SATA cable assembly consists of the connector, PCB and cable in series. Three components and their assembly are investigated with their differential mode S-parameters. Also, the insertion loss, reflection loss and differential impedance of the components are calculated to analyze their signal transmission characteristics. Each component has approximately 100  of the differential impedance. However, their high-frequency responses such as insertion loss and reflection loss show different characteristics. While the connector and cable present the excellent signal transmission performance, the printed circuit board (PCB) has lower characteristics despite the shortest trace length. The insertion loss and reflection loss of SATA cable assembly are investigated and have a similar tendency with those of the PCB. These results verify that signal transmission properties of the SATA cable assembly are affected significantly by the PCB with the largest loss.

Novel design for microstrip to stripline transitions for millimeter-wave application in LTCC

This paper presents two transitions between microstrip and stripline in Low Temperature Co-fired Ceramic technology, including a vertical transition and a coplanar transition for millimeter-wave application. These interconnects are simulated and optimized by a three-dimensional electromagnetic field simulator. Simulation results show that the return loss of microstrip to stripline vertical transition is less than −22dB, and insertion losses are greater than 0.5dB up to 35GHz, and greater than 1dB up to 40GHz. Similarly, the return loss of the coplanar transition is less than −32dB and insertion loss is better than 0.5dB. LTCC test structures were fabricated and the performance of all transitions was successfully validated by scattering parameter measurements up to 40GHz.

Jones and Stokes parameters for polarization in three dimensions

For partially polarized three-dimensional electromagnetic fields, the polarization state is usually expressed in terms of nine generalized Stokes parameters, the coefficients of the nine Gell-Mann matrices in the expansion of the coherency matrix. We consider fully polarized fields, for which the Jones vector for the polarization state can be expressed in terms of five real parameters. Relationships between these five parameters and the nine generalized Stokes parameters are derived. For partially polarized three-dimensional fields there are four additional parameters that describe the partial polarization, two that specify the degree of polarization, and two that specify its orientation.

Signal Transmission Analysis of Burn-In Socket for Fine-Pitch Ball Grid Array Package

Signal transmission analysis is investigated for a burn-in socket of fine-pitch ball grid array (FBGA) package using a three-dimensional electromagnetic field simulation. The effects of different signal-ground pin assignments on its signal transmission characteristics are analyzed in this work. Also, its electric and magnetic fields are presented to evaluated their distribution intensity around the signal and ground pins. Its reflection and insertion losses are calculated to analyze the effects of the increase in the contact length. For a burn-in socket with a contact length of 3 mm, the 1-dB the insertion loss frequency is calculated to be 38 GHz. The calculation results for insertion loss and reflection loss show that the frequency characteristics of the burn-in socket are excellent, and that the burn-in socket is suitable for high-speed applications.

The Full Calculation of Three-Dimensional Quasi-Stationary Electromagnetic Fields in Approach of the Strong Skin Effect by the Method of the Boundary Integral Equations

The efficient method of the boundary integral equations allowing to carry out the full simulation of three-dimensional quasi-stationary electromagnetic fields in approach of the strong skin effect is devised and realized. Examples of calculations of modeling and real systems of formation of quasistationary electromagnetic fields are given. The comparisons of results of simulation with analytical solutions and observed data are presented

Measurement and Simulation of Magnetic Field Generated by Screening Currents in HTS Coil

In coils wound with high-temperature superconducting (HTS) tapes, large screening currents are induced in the tape by the radial component of the magnetic field. Furthermore, when a transport current is supplied to the HTS tape under a magnetic field, the total current (which consists of the transport and screening currents) flows inhomogeneously. The magnetic field generated by the screening currents affects the magnetic field distribution in cyclotron applications. Investigating the effects of the screening currents on the reduction, hysteresis, and drift of the magnetic field in the HTS coil is therefore necessary. In our previous studies, we have developed a novel simulation code for a three-dimensional electromagnetic field with the aim of clarifying these effects. In the present study, we measured the reduction and hysteresis of the magnetic field generated by the screening currents for a small model of HTS pancake coil. Additionally, we numerically investigated the influence of the screening current in the HTS coil on the spatial and temporal behavior of the magnetic field using our developed simulation code, which considers the nonlinear voltage-current characteristics.

Numerical Calculation and Analysis of Three-Dimensional Transient Electromagnetic Field in the End Region of Large Water–Hydrogen–Hydrogen Cooled Turbogenerator

Due to the complexity of the structures and magnetic field distribution in the end region of large turbogenerators, using a 330-MW water-hydrogen-hydrogen cooled turbogenerator as an example, the 3-D mathematical and geometry models of the nonlinear transient eddy current field were given. Taking the nonlinearity of the core material and the influences of noncontact between the copper screen and the clamping plate, as well as the shape of stator end windings into consideration, the 3-D transient electromagnetic field was calculated, and the losses of different metal parts were obtained by the finite-element method. The calculated power losses were applied to the thermal field as heat sources. Temperatures of the copper screen were gained. The calculated results of copper screen were well coincident with the test data. Hence, the calculated results are accurate, and the method of calculation is effective.

Modeling of Electromagnetic Field and Liquid Metal Pool Shape in an Electroslag Remelting Process with Two Series-Connected Electrodes

A three-dimensional finite-element model has been developed to understand the electromagnetic field and liquid metal pool shape in an electroslag remelting (ESR) process with two series-connected electrodes. The magnetic vector potential is introduced into the Maxwell’s equations, and the nodal-based method is used to solve a three-dimensional harmonic electromagnetic field. The heat transfer of the solidifying processes of ingot is modeled by a source-based enthalpy method, and the Joule heating is included in an inner source. The results show the main part of the current flows through the slag cap and a little enters into ingot in a two-series-connected electrode ESR system. As the interaction of self-induced and mutual-induced of two electrodes occurs, the skin effect is significantly suppressed by the neighbor effect. A symmetrical pattern of magnetic flux density in a two-series-connected electrode ESR system is displayed. The magnetic flux density between two electrodes is reinforced and reduced at the outside of two electrodes. The maximum Joule heat power density is located at the interface of slag and electrodes, and it decreases with an increase of the electrode immersion depth. The averaged Joule heat power density increases when slag cap thickness is reduced. With the increase of ingot height, the liquid metal pool shape changes from arc shaped to “V” shaped. When the ingot height is more than the diameter in the ESR processes, the liquid metal pool shape is constant.

Equivalent Electromagnetic Constants for Microwave Application to Composite Materials for the Multi-Scale Problem.

To connect different scale models in the multi-scale problem of microwave use, equivalent material constants were researched numerically by a three-dimensional electromagnetic field, taking into account eddy current and displacement current. A volume averaged method and a standing wave method were used to introduce the equivalent material constants; water particles and aluminum particles are used as composite materials. Consumed electrical power is used for the evaluation. Water particles have the same equivalent material constants for both methods; the same electrical power is obtained for both the precise model (micro-model) and the homogeneous model (macro-model). However, aluminum particles have dissimilar equivalent material constants for both methods; different electric power is obtained for both models. The varying electromagnetic phenomena are derived from the expression of eddy current. For small electrical conductivity such as water, the macro-current which flows in the macro-model and the micro-current which flows in the micro-model express the same electromagnetic phenomena. However, for large electrical conductivity such as aluminum, the macro-current and micro-current express different electromagnetic phenomena. The eddy current which is observed in the micro-model is not expressed by the macro-model. Therefore, the equivalent material constant derived from the volume averaged method and the standing wave method is applicable to water with a small electrical conductivity, although not applicable to aluminum with a large electrical conductivity.

Large tuning ratio high aspect ratio variable capacitors using leveraged bending

Variable capacitors are a key component in Radio Frequency Micro Electro-Mechanical Systems (RF MEMS). They comprise fixed and flexible electrodes. Deformation, or actuation, of the flexible electrode changes the capacitance of the capacitor. This way, electrical properties of high frequency circuits can be modified. Traditionally, variable capacitors are based on a planar layout architecture, while a newer, vertical-wall, quasi three-dimensional approach theoretically enables increased device performance. Such devices depend on high aspect ratios, i.e. relatively high micro structures with very thin walls and gaps. A few vertical-wall variable capacitors made of nickel or gold have been fabricated to date, using deep X-ray lithography and subsequent electroplating (Achenbach et al. 2006; Klymyshyn et al. 2007, 2010) as the fabrication approach. They feature, amongst others, excellent quality factors of Q ≤ 95 at 5.6 GHz with 50 Ω reactance, but suffer from a very limited tuning range of the capacitance value (tuning ratio of, e.g., 1.38:1). The devices presented here exploit the same architecture and materials selection, resulting in similar, excellent Q-factors, but feature a different electrode layout approach, referred to as leveraged-bending. This layout is based on pulling a flexible electrode sideways, towards a fixed electrode, increasing the capacitance when actuating the variable capacitor. The leveraged bending approach theoretically enables infinitely high tuning ratios for components with perfect structure accuracy. To date, a significantly increased tuning ratio of 1.9:1 has been demonstrated. Limiting factors are an electrically non-ideal layout geometry chosen as a compromise to increase the fabrication yield, and structure deviations of ~1.6 μm from CAD layout to the electroplated component. Electrostatic actuation requires voltages between 0 and 72 V for capacitance values on the order of C = 0.3 pF at device dimensions of about 1.5 mm overall length, 5---10 μm gap and wall widths, and 100 μm metal height. Device performance measured with a vector network analyzer is in 97 % agreement with simulation results based on two-dimensional electrostatic-structural coupling (ANSYS Multiphysics) and three-dimensional electromagnetic field simulations (Ansoft HFSS). These simulations also indicate that an optimized gap geometry will allow to reduce the actuation voltage required by up to 40 %.

A Comparative Study of Novel Permanent Magnet Arc Guideway Motors Based on Three-Dimensional Electromagnetic Field Analysis

A novel PM arc guideway motor (PMAGM) is developed due to the drawback of the conventional motor reciprocating within certain angle. The PMAGM can directly drive load to make reciprocating motion within a limited angle with advantages of simplification, reliability, high efficiency, etc.. Aiming at the permanent magnet (PM) magnetization and solenoid coil electrifying modes, the PM deflection angle is parameterized and the influence on electromagnetic force has been analyzed between different magnetization and electrifying modes. Results show that electromagnetic force in Y direction magnetized along the external field force lines at proposal 1 is 51.23% higher than that of vertical magnetization, and the electromagnetic resultant force increases by 45.91%. As the angle of the PM deflection within 3o, the electromagnetic force in X direction points to the right, which is not good for PM slidable assembly swing. Based on comprehensive analysis of the advantages and disadvantages of several electrifying modes, the electricity combination under full swing angle is optimized.

Fourier domain optical tool normalization for quantitative parametric image reconstruction

There has been much recent work in developing advanced optical metrology methods that use imaging optics for critical dimension measurements and defect detection. Sensitivity to nanometer-scale changes has been observed when measuring critical dimensions of subwavelength 20 nm features or when imaging defects below 15 nm using angle-resolved and focus-resolved optical data. However, these methods inherently involve complex imaging optics and analysis of complicated three-dimensional electromagnetic fields. This paper develops a new approach to enable the rigorous analysis of three-dimensional, through-focus, or angle-resolved optical images. We use rigorous electromagnetic simulation with enhanced Fourier optical techniques, an approach to optical tool normalization, and statistical methods to evaluate sensitivities and uncertainties in the measurement of subwavelength three-dimensional structures.