Commercial Electromagnetic Simulation Research Articles

Electromagnetic shielding effectiveness of carbon fibre reinforced composites

This paper reports results on the shielding effectiveness parameter of laminated epoxy composites with carbon fibre reinforcements. Measurements of shielding effectiveness were carried out with a coaxial transmission line testing chamber according to ASTM 4935 standard and epoxy-matrix composites with continuous carbon-fibres were proven to be an excellent electromagnetic interference shielding material, where a composite slab made of 4 layers of prepregs provided more than 99.9% of electromagnetic attenuation. It was found that the reflection mechanism of the shielding material was mainly influenced by the fibre volume ratio, and that an increase in the number of layers of the composite resulted in higher shielding effectiveness due to a greater absorption mechanism. Calculations of the shielding effectiveness parameter of the material used were made by means of commercial electromagnetic simulation tools, having determined experimentally the overall resistivity of the composite. The findings presented in this work suggest that in presence of a greater number of interfaces at different impedance the separate modelling of matrix and fibres at mesoscopic scale must be taken into account.

Design of Broadband W-Band Waveguide Package and Application to Low Noise Amplifier Module

In this paper, the broadband millimeter-wave waveguide package, which can cover the entire W-band (75–110 GHz) is presented and applied to build a low noise amplifier module. For this purpose, a broadband waveguide-to-microstrip transition was designed using an extended E-plane probe in a low-loss and thin dielectric substrate. The end of the probe substrate was firmly fixed on to the waveguide wall in order to minimize the performance degradation caused by the probable bending of the substrate. In addition, we predicted and analyzed in-band resonances by the simulations that are caused by the empty spaces in the waveguide package to accommodate integrated circuits (ICs) and external bias circuits. These resonances are removed by designing an asymmetrical bias space structure with a radiation boundary at an external bias connection plane. The bond-wires, which are used to connect the ICs with the transition, can generate impedance mismatches and limit the bandwidth performance of the waveguide package. Their effect is carefully compensated for by designing the broadband two-section matching circuits in the transition substrate. Finally, the broadband waveguide package is designed using a commercial three-dimensional electromagnetic structure simulator and applied to build a W-band low noise amplifier module. The measurement of the back-to-back connected waveguide-to-microstrip transition including the empty spaces for the ICs and bias circuits showed the insertion loss less than 3.5 dB and return loss higher than 13.3 dB across the entire W-band without any in-band resonances. The measured insertion loss includes the losses of 8.7 mm-long microstrip line and 41.8 mm-long waveguide section. The designed waveguide package was utilized to build the low noise amplifier module that had a measured gain greater than 14.9 dB from 75 GHz to 105 GHz (>12.9 dB at the entire W-band) and noise figure less than 4.4 dB from 93.5 GHz to 94.5 GHz.

Miniaturised antenna at a sub‐GHZ band for industrial remote controllers

This study presents the design and the fabrication of a miniaturised sub-GHz antenna for remote control applications. Miniaturisation techniques were examined to identify the most appropriate topology for sub-GHz band requirements. First, the design parameters of the antenna were determined, and then, a commercial electromagnetic simulation tool was used for the design and optimisation phases. Then, measurements of the fabricated antenna were undertaken. Parametric studies with several iterations were performed to achieve the best possible results. Second, the effects of the box in which the antenna could be placed were examined as most of such antennas are enclosed by plastic boxes. For this purpose, material properties of a typical industrial box available in the market were studied initially, and the most appropriate material of the box was used in simulations. Finally, a polyamide box with appropriate size was fabricated, and the designed antenna was placed inside the box and the measurements were conducted. The measurement results show that the designed antenna provides resonance at the targeted license-free band with adequate size for industrial remote controllers.

Multi-Semicircle-Based Single- and Dual-Band Frequency-Selective Surfaces: Achieving Narrower Bandwidth and Improved Oblique Incidence Angular Stability

This article proposes two new frequency-selective surface (FSS) designs based on specific combinations of a multiple number of semicircles. One of the proposed designs makes use of four semicircles, yielding a single-band frequency response. The other consists of a combination of eight semicircles arranged in a square-like shape, producing a dual-band frequency response. The proposed designs were simulated with commercial electromagnetic simulation software.

Conductor losses calculation in two-dimensional simulations of H-plane rectangular waveguides

ABSTRACTThis paper presents a novel numerical approach to simulate H-plane rectangular-waveguide microwave circuits considering a reduced quasi-2D simulation domain with benefits for computational cost and time. With the aim to evaluate the attenuation of the full height 3D component, we propose a modified expression for the waveguide top/bottom wall conductivity. Numerical 2D simulations are validated against results from full wave 3-D commercial electromagnetic simulator. After a benchmark on a simple straight waveguide model, the method has been successfully applied to an asymmetric un-balanced power splitter, where an accurate power loss prediction is mandatory. Simulation time and memory consumption can be reduced by a factor ten and seven respectively, in comparison with complete 3D geometries. Finally, we show that, also for quasi-2D E-bend waveguide, a case where the translational H-plane symmetry is broken, the error on conductor losses computation is mitigated by our approach since the method remains still valid in a first approximation.

Implementation of a Dual Wireless Power Transfer and Rotation Monitoring System for Prosthetic Hands

This article presents the design, manufacture and test of an inductively coupled wireless power transfer (WPT) system used as a power source for prosthetic hands. Prosthetic hands are the most common artificial limbs among the physically disabled population. Limited storage capacity of the battery places severe limitations regarding the continuous use of this device. A WPT link is therefore proposed to supply power to such devices. The WPT system consists of a transmitter circuit (class-E power amplifier) and WPT coils along with commercially available receiver circuit and multiple motors. Assessment of the unwanted heating of the human tissue due to wireless power transfer was simulated using the commercial electromagnetic simulator ANSYS HFSS™. Results were experimentally validated by measuring in real-time temperature variations inside a phantom mimicking the properties of human muscle. Monitoring and control the rotation of the prosthetic hand was also demonstrated utilizing rotation-dependent wireless power transfer parameters. The WPT scheme proposed serves therefore the dual property of providing power to the prosthetic limb whilst monitoring the wrist rotation.

Parallel ring‐line rat‐race circuit with very loose coupling

AbstractThis article describes rat‐race circuits (RRCs) in which a pair of ring‐lines have parallel lines of ±180‐degree difference for electrical length to realize the RRC with very loose coupling such as −10 dB or less. The proposed RRCs with parallel ring‐lines realize a coupling factor of −10 dB and −20 dB by using moderate characteristic impedance lines with a view point of fabrication tolerance for general PCB technologies. We confirm the validity of this circuit construction and design method using a commercial electromagnetic simulator and decide the circuit pattern for fabrication at a center frequency of 2.45 GHz. The fabricated RRCs with parallel ring‐lines realize the desired coupling factors and in‐/out‐of‐phase outputs, and the measurement results of scattering parameters for −10 dB and −20 dB RRCs are in good agreement with the simulation results.

A Fast and Accurate Analytical Method Based on Input Impedance for Antenna Directivity [Antenna Applications Corner

A novel, fast, and accurate analytical method based on input impedance is proposed for antenna directivity determination. The detailed theoretical expressions are examined and presented to determine the directivity of the wire-dipole and biconical antennas. The proposed analytical directivity results of the antennas are compared with conventional methods and measurements as well as a commercial electromagnetic (EM) simulator. A good correlation is achieved between the proposed method, the CST full-wave EM simulator, and the measurements. Additionally, the proposed method can be used to determine the antenna directivity in complicated environments, i.e., large array, for which the antenna characteristics may be deviated under coupling effects.

Electrical Modeling and Characterization of Silicon-Core Coaxial Through-Silicon Vias in 3-D Integration

Based on the extracted resistance, inductance, capacitance, and conductance parameters, this paper introduces the distributed transmission line model of silicon-core coaxial through-silicon vias (CTSVs), in which the vertical interconnect is made of a Cu-coated silicon pole. The proposed model is validated against a commercial electromagnetic simulation tool, showing it is highly accurate up to 100 GHz. Using the proposed model, the impact of various material properties and physical parameters on the electrical performance of the silicon-core CTSVs is investigated. It is observed that the thickness of the plated Cu and isolation dielectric are two important parameters that determine the electrical performance of silicon-core CTSVs. Performance comparison shows that the proposed silicon-core CTSVs provide a comparable performance to standard Cu-based CTSVs and better performance to the conventional signal-ground TSV pairs. The results in this paper would provide some design guides for silicon-core CTSVs in 3-D integration.

An advanced numerical technique for a quasi-static electromagnetic field simulation based on the finite-difference time-domain method

In this paper, an advanced numerical technique is proposed for a low-frequency electromagnetic field simulation. The finite difference time domain (FDTD) method is one of the best methods for analyzing electromagnetic field problems, which require high levels of precision, such as a heterogeneous whole-body voxel human model. However, directly using the standard FDTD method in the quasi-static frequency band requires an extra-large number of iterations. We overcome this drawback using the hybrid of surface equivalence theorem and quasi-static FDTD (QS-FDTD) method. The surface equivalence theorem is used to consider arbitrary shape of source and the QS-FDTD is applied to obtain electromagnetic response quickly in the low-frequency region. The results of the proposed method are in good agreement with those from a commercial electromagnetic simulator. The proposed method is valid where the quasi-static approximation is satisfied.

A unified analysis framework for tensor metasurfaces

Tensor impedance metasurfaces have attracted much attention recently due to their ability to flexibly manipulate both propagating and surface waves. So far, the analysis of tensor impedance has not been fully supported by commercial electromagnetic simulation software. Also, the representation of formulas of penetrable tensor impedance for both propagating and surface waves is limited in the literature. Hence, a unified analysis framework is proposed for this purpose. It allows the calculation of wave reflection and transmission with arbitrary incident angles, or inversely, the calculation of surface impedance tensors given the desired wave propagation properties. It also allows surface eigenmode analysis, where surface modes with novel isofrequency contours are found for penetrable tensor impedance surfaces. The relationship between penetrable and impenetrable metasurfaces is derived so that the resultant formulas are applicable in both scenarios. A finite difference method code is implemented to validate the derived formulas. The proposed unified formulas are of closed form, hence offering very fast operation for research and design of tensor impedance metasurfaces.

Electromagnetic modeling of anisotropic ferrites—Application to microstrip Y-junction circulator design

This paper presents a theoretical tool, which combines a generalized permeability tensor model, a homemade 3D magneto-static solver, and a commercial electromagnetic simulation software Ansys HFSS™ for accurate modeling of ferrite-based devices regardless of their state of magnetization. A magneto-static analysis is carried out to find the internal biasing fields in the ferrite sample. Permeability tensor components are computed using a generalized permeability tensor model. Real and imaginary parts of permeability tensor components are then integrated into the commercial 3D electromagnetic simulation software HFSS retaining the spatial variations of internal biasing fields in the ferrite sample. Frequency domain simulations are done using HFSS. This theoretical modeling approach is validated by comparing the theoretical simulation results with experimental ones in the case of a coaxial line loaded by a magnetized ferrite. Proposed approach is then applied to the design of a microstrip Y-junction circulator. Finally, a demonstration prototype is manufactured in the Low Temperature Co-fired Ceramics technology.

Solid-State Conductive-Bridging Reconfigurable RF-Encoding Particle for Chipless RFID Applications

We report the design and first results of a reconfigurable RF-encoding particle (REP) for chipless RFID tag, based on a Nafion conductive-bridging random-access memory cell. The developed tag consists of a modified shorted dipole as REP, equipped with a copper-Nafion-aluminum metal-insulator-metal (MIM) nonvolatile ionic-bridging switch. The MIM switch is similar to an RC parallel network, which tunes the electrical length of the resonator. The chipless tags switch between two different resonant frequencies, in the set and reset states of the switch. An electrical model is also developed for the REP to explain the mechanism of switching. The experimental results are in close agreement with the simulation results using commercial electromagnetic simulators. This letter is a proof of concept of electronically reconfigurable chipless tags based on integrated switches which have the potential to be directly printed along with the tag.

Miniaturised planar‐patch antenna based on metamaterial L‐shaped unit‐cells for broadband portable microwave devices and multiband wireless communication systems

This study describes the design of a metamaterial planar antenna for multi-octave band operation. The metamaterial unit-cell comprises L-shaped slit which is etched inside a rectangular patch with a grounded inductive spiral. The slit essentially behaves as a series left-handed capacitance and the spiral as a shunt left-handed inductance. The antenna was modelled and optimised for impedance bandwidth, gain and efficiency performance using commercial three-dimensional full-wave electromagnetic simulation tools. The antenna has a measured impedance bandwidth of 6.02 GHz for S 11<−10 dB. This corresponds to a fractional bandwidth of 172.49%, which is higher than multiband planar antennas reported to date. The antenna has a maximum gain and efficiency performance of 3.7 dBi and 73%, respectively, at 3.25 GHz. The physical footprint of the antenna is comparable to other wideband planar antennas reported to date. The overall size of the antenna is 0.037λ 0 × 0.027λ 0 × 0.002λ 0 and 0.25λ 0 × 0.18λ 0 × 0.017λ 0, where λ 0 is free-space wavelength at 0.48 and 3.25 GHz, respectively.

Inductance Modeling of Interconnections in 3-D Stacked-Chip Packaging

This letter explores the inductance of interconnections including through-silicon vias (TSVs) and redistribution layers (RDLs) in 3-D stacked-chip packaging. It is described that the common summing method of partial inductances will result in some deviations from the full inductance. Then, the inductances of TSVs and RDLs are, respectively, calculated and are verified by a commercial electromagnetic simulator. The modified formulas are proposed for the more accurate full inductance model, which is derived from different design physical parameters of the interconnections. The side effect of a general summing method can be reduced a lot by our proposed analytical model.

Self-Calibrating Noniterative Complex Permittivity Extraction of Thin Dielectric Samples

A microwave method relying on uncalibrated scattering (S-) parameters is proposed to measure the complex permittivity ( $\varepsilon _r$ ) of thin dielectric samples. It has the following two main advantages. First, it takes into account effect of the sample holder, used for holding the sample, especially important for thin sample electromagnetic property characterization. Second, it does not require any specific information about the location of the sample (and its holder) inside its measurement cell for $\varepsilon _r$ extraction. For validation of our method, we applied a commercial three-dimensional electromagnetic simulation program—CST Microwave Studio—and the Lorentz dispersion model. Uncalibrated (as well as calibrated) S-parameter measurements were conducted to measure $\varepsilon _r$ of a 0.7 mm thick polyethylene sample (the sample holder was a 5.18 mm thick PVC sample) by our method and other similar methods in the literature. From the comparison, we observed that while the accuracy of tested methods significantly changed with inaccurate knowledge of the sample position inside its cell, the accuracy of our method did not much alter.

Infinitesimal Dipole Model Using Space Mapping Optimization for Antenna Placement

The infinitesimal dipole model (IDM) is very appealing for antenna placement problems, especially since antenna design details need not be available. The method has been mainly used to model antennas radiating in free space or above an infinite perfectly conducting ground plane, with synthetic data. The direct application of the method considering finite ground planes is impracticable because of the complexity of the associated Green's functions. In this letter, we propose a methodology to devise the equivalent model, taking into account edge diffraction effects due to the finite ground plane, but still maintaining a relatively low computational cost. We combine the classical IDM with the output space mapping technique so that the burden of model optimization is placed on the analytical model, and the more accurate but computationally intensive model is evaluated only a few times. To demonstrate the applicability of the method, we model a radar altimeter antenna operating at 4.3 GHz in a typical case of antenna integration: Only the measured far-field data are available. The equivalent model obtained is then incorporated into a commercial electromagnetic simulation package to compare its installed radiation pattern with the actual antenna measured pattern. An excellent agreement is verified.

Reduction of wireless signals in indoor environments by using an active frequency selective wall based on spectrum sensing

SummaryThis paper presents a wireless local area network (WLAN) spectrum control system that uses active frequency selective shielding walls to selectively reduce or pass WLAN signals in the 5 GHz band indoors. The proposed system utilizes a well‐known active frequency selective structure based on a rectangular loop with PIN diodes and is thus capable of either reducing or passing the WLAN frequency by using the on/off switching of the PIN diode based on the measured electric field strength in indoor. We designed and simulated the proposed active frequency selective shielding wallpaper by using commercial electromagnetic simulation software and confirmed that the proposed structure can reduce the WLAN signal by switching the PIN diode by applying the manufactured prototype on the exterior of an experimental apparatus containing a WLAN receiver antenna that is capable of measuring the received electric field strength. Extension of the results presented herein can be applied to reduce the wireless signal to enhance the spectrum efficiency of an indoor space.

Fourcross shaped metamaterial filters fabricated from high temperature superconducting YBCO and Au thin films for terahertz waves

In this study, we present a new, unique fourcross shaped metamaterial terahertz (THz) filter fabricated from both gold thin films and YBa2Cu3O7−d high Tc superconducting thin films. A commercial electromagnetic simulation software, CST Microwave Studio, is used to design and optimize the metamaterial filter structures. The proposed fourcross shaped rectangular filter structure consists of periodic metallic rings where strip lines are located at the sides of the ring. Fourcross metamaterial filters are fabricated by using e-beam lithography and ion beam etching techniques. Terahertz time-domain spectroscopy measurements validated the design predictions for both the center frequencies and bandwidths of the resonances due to the fourcross structures. The resonance switching of the transmission spectra was investigated by lowering the temperature below the critical transition temperature. This resonance switching effect is not observed in filters made up of metals. This novel fourcross rectangular resonator with a temperature-dependent resonance behavior holds great potential for active, tunable and low loss THz devices for imaging, sensing, and detection applications.

GUI design exploration software for microwave antennas

Abstract Optimizers in commercial electromagnetic (EM) simulation software packages are the main tools for performing antenna design exploration today. However, these general purpose optimizers are facing challenges in optimization efficiency, supported optimization types and usability for antenna experts without deep knowledge on optimization. Aiming to fill the gaps, a new antenna design exploration tool, called Antenna Design Explorer (ADE), is presented in this paper. The key features are: (1) State-of-the-art antenna design exploration methods are selected and embedded, addressing efficient antenna optimization (critical but unable to be solved by existing tools) and multiobjective antenna optimization (not available in most existing tools); (2) Human-computer interaction for the targeted problem is studied, addressing various usability issues for antenna design engineers, such as automatic algorithmic parameter setting and interactive stopping criteria; (3) Compatibility with existing tools is studied and ADE is able to co-work with existing EM simulators and optimizers, combining advantages. A case study verifies the advantages of ADE. Highlights A new antenna design exploration tool, called Antenna Design Explorer (ADE), is presented in this paper. State-of-the-art antenna design exploration methods are selected and embedded, addressing efficient antenna optimization (critical but difficult to be solved by existing tools) and multiobjective antenna optimization (not available in most existing tools). Human-computer interaction for the targeted problem is studied, addressing various usability issues for antenna design engineers. Compatibility with existing tools is studied and ADE is able to co-work with existing EM simulators and optimizers, combining advantages.