Transverse Electromagnetic Research Articles

An EMI-Immune PAM-4 Transmitter With Input Level Shifter in 130-nm BiCMOS Technology

This work presents a design of an electromagnetic interference (EMI)-immune pulse amplitude modulation-4 (PAM-4) transmitter. The traditional PAM-4 transmitters are prone to failing in the presence of EMI, which is experimentally verified. The proposed PAM-4 shows superior performance over the traditional PAM-4 transmitter, in the presence of EMI, by using an Input Level Shifter (ILS). ILS minimises the effect of EMI on a PAM-4 signal by reducing the input commonmode level of the transmitter and renders it compatible with the previous logic state. The proposed PAM-4 transmitter is fabricated in 130-nm BiCMOS technology with a chip area of 580mum×915 mum. EMI-immunity measurements are aligned with the IEC 62132-2 standard by using a transverse electromagnetic (TEM) cell for radiated EMI-immunity. In the presence of a wide range of EMIs, the proposed PAM-4 transmitter operates at a data rate of 6.5 Gbps and maintains the minimum required eye-opening of 70mV as per the standard IEEE 802.2bs. The proposed EMI-immune transmitter can withstand EMI powers of 0-16dBm in frequencies ranging from 1MHz to 1.5 GHz.

Variational, stable, and self-consistent coupling of 3D electromagnetics to 1D transmission lines in the time domain

This work presents a new multiscale method for coupling the 3D Maxwell's equations to the 1D telegrapher's equations. While Maxwell's equations are appropriate for modeling complex electromagnetics in arbitrary-geometry domains, simulation cost for many applications (e.g. pulsed power) can be dramatically reduced by representing less complex transmission line regions of the domain with a 1D model. By assuming a transverse electromagnetic (TEM) ansatz for the solution in a transmission line region, we reduce the Maxwell's equations to the telegrapher's equations. We propose a self-consistent finite element formulation of the fully coupled system that uses boundary integrals to couple between the 3D and 1D domains and supports arbitrary unstructured 3D meshes. Additionally, by using a Lagrange multiplier to enforce continuity at the coupling interface, we allow for an absorbing boundary condition to also be applied to non-TEM modes on this boundary. We demonstrate that this feature reduces non-physical reflection and ringing of non-TEM modes off of the coupling boundary. By employing implicit time integration, we ensure a stable coupling, and we introduce an efficient method for solving the resulting linear systems. We demonstrate the accuracy of the new method on two verification problems, a transient O-wave in a rectilinear prism and a steady-state problem in a coaxial geometry, and show the efficiency and weak scalability of our implementation on a cold test of the Z-machine MITL and post-hole convolute.

Trapping of light by discontinuities of magnetization in a gyrotropic (meta) material

We show that an interface between two identical metal/dielectric plane-layered ferromagnetic (meta)materials with different directions of magnetization can support electromagnetic surface waves (SWs) of the visible or near-infrared band. We find that such an interface possesses so-called valve action allowing the propagation of SWs only within definite range of angles (including strictly unidirectional propagation), depending on the mutual orientation of magnetizations in the contacted media and filling factor of ferromagnetics in the metamaterial. Furthermore, these SWs can demonstrate unusual properties for conventional surface plasmon-polaritons, namely, a transverse electromagnetic (TEM) structure with zero angular momentum. We also reveal that in a plane-layered metal/dielectric metamaterial the weak optical gyrotropy can be considerably enhanced due to quasi-static LC resonance in this structure.

Polarization insensitivity characterization of dual-band perfect metamaterial absorber for K band sensing applications

Polarization insensitive metamaterial absorbers (MA) are currently very attractive due to their unique absorption properties at different polarization angles. As a result, this type of absorber is widely used in sensing, imaging, energy harvesting, etc. This paper presents the design and characterization of a dual-band polarization-insensitive metamaterial absorber (MA) for K-band applications. The metamaterial absorber consists of two modified split ring resonators with an inner cross conductor to achieve a 90% absorption bandwidth of 400 MHz (21.4–21.8 GHz) and 760 MHz (23.84–24.24 GHz) at transverse electromagnetic (TEM), transverse electric (TE), and transverse magnetic (TM) mode. Polarization insensitivity of different incident angles for TE and TM mode is also investigated, which reveals a similar absorption behavior up to 90°. The metamaterial structure generates single negative (SNG) property at a lower frequency of 21.6 GHz and double negative property (DNG) at an upper frequency of 24.04 GHz. The permittivity and pressure sensor application are investigated for the proposed absorber, which shows its useability in these applications. Finally, a comparison with recent works is also performed to demonstrate the feasibility of the proposed structure for K band application, like sensor, filter, invasive clock, etc.

Ultra-Wideband and Wide-Angle Insensitive Absorber Based on TCDA-Under-Tightly Coupled Dipole Array

In this article, an ultra-wideband and wide-angle insensitive absorber is proposed. The unit cell of the proposed structure consists of a tightly coupled dipole array (TCDA2) under another TCDA (TCDA1) that is twice the height of TCDA2 (TCDA-under-TCDA structure). TCDA1 of the unit cell acts as either a lossless (or lossy) antenna when the frequency is out of (or in) the operating frequency range of TCDA2. Reciprocity is applied to design TCDA1 as an absorber when the frequency is out of the operating frequency range of TCDA2 (lossless antenna region). On the other hand, the multisection impedance matching technique is applied for TCDA1 to be an absorber when the frequency is in the operating region of TCDA2 (lossy antenna region and reciprocity cannot be applied). In addition, a metasurface (MS) and vertical metal strip (VMS) are employed to develop the wide-angle insensitivity absorber. A -10 dB reflection bandwidth of 0.63-6.55 (10.4:1) is achieved with a 0.126λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">low</sub> at the lowest operating frequency under normal incidence. The bandwidth is moderately reduced to 0.69-6.75 (9.78:1) with a 0.138λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">low</sub> for the TE mode and 0.75-6.22 (8.29:1) with a 0.150λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">low</sub> for the TM mode under 45° oblique incidence. The measured results of the fabricated absorber using the transverse electromagnetic (TEM) cell are in good agreement with the simulated results.

Near-Field Scanning Based Shielding Effectiveness Analysis of System in Package

The electromagnetic interference (EMI) problems are crucial for system-in-package (SiP) due to the high demand of miniaturization and dense integration. Shielding methods are generally employed to protect SiP from EMI, through assessing the key performance index, i.e., shielding effectiveness (SE). In this article, the SE of a SiP is evaluated by using near-field scanning method. The SEs derived by using maximum near-field values and average near-field values are comparatively analyzed. The difference in near-field patterns of the unshielded and shielded SiPs may incur overestimation of the SE by using maximum field values. Both simulation and measurement results manifest that the gap between SiP and printed circuit board (PCB) will significantly change the radiation pattern of a shielded SiP, and thus has a great impact on the SE, especially when the frequency is above 1 GHz. However, a good correlation is found between the SE based on average near-field and the SE derived from the radiated power. This study has revealed the near-field shielding properties of SiP, which is helpful for building and analyzing the correlation among the SEs measured by different methods, including the near-field scanning, transverse electromagnetic (TEM) cell and reverberation chamber.

A Linear Microwave Plasma Source Using a Circular Waveguide Filled with a Relatively High-Permittivity Dielectric: Comparison with a Conventional Quasi-Coaxial Line Waveguide

For a conventional linear microwave plasma source (LMPS) with a quasi-coaxial line transverse electromagnetic (TEM) waveguide, a linearly extended plasma is sustained by the surface wave outside the tube. Due to the characteristics of the quasi-coaxial line MPS, it is easy to generate a uniform plasma with radially omnidirectional surfaces, but it is difficult to maximize the electron density in a curved selected region. For the purpose of concentrating the plasma density in the deposition area, a novel LMPS which is suitable for curved structure deposition has been developed and compared with the conventional LMPS. As the shape of a circular waveguide, it is filled with relatively high-permittivity dielectric instead of a quasi-coaxial line waveguide. Microwave power at 2.45 GHz is transferred to the plasma through the continuous cylindrical-slotted line antenna, and the radiated electric field in the radial direction is made almost parallel to the tangential plane of the window surface. This research includes the advanced 3D numerical analysis and compares the results with the experiment. It shows that the electron density in the deposition area is higher than that of the conventional quasi-coaxial line plasma MPS.

Novel Suspended-Line Gap Waveguide Packaged With Stacked-Mushroom EBG Structures

A novel low-loss suspended-line gap waveguide (SLGW) supporting transverse electromagnetic (TEM) propagation is presented for millimeter-wave applications for the first time. The suspended line is composed of two parallel strips connected by metal via holes. Periodic stacked-mushroom electromagnetic band gap (SM-EBG) structures are used to package the suspended line by creating a stopband for all parallel-plate modes. According to the different packaging requirements of the circuit, the SM-EBG unit cell can be composed of several stacked mushrooms and metal covers. The air gaps’ thickness between face-to-face patches of the adjacent mushrooms is near zero, confining more power in the air-filled guiding region of the SLGW. Furthermore, the SM-EBG structures with near-zero thick air gaps can provide more stable mechanical support for the multilayer structure. Therefore, SLGW has a lower loss and more robust gap stability compared with the conventional air-filled printed versions of GWs, such as printed ridge gap waveguide (PRGW) and inverted microstrip gap waveguide (IMGW). On the other hand, compared with the self-packaged double-sided interconnected strip line (DSISL), the proposed SLGW packaged with SM-EBG structures has the advantage of no electrical contact, avoiding the power leakages in the gap between plates at discontinuities and simplifying the assembly. The design and analysis of the SM-EBG structure, the design of SLGW, and the microstrip-to-SLGW transition design are given in this article. A prototype of the proposed SLGW with back-to-back transition is fabricated packaged with SM-EBG structures to prove the concept.

Circuit Model of an Overhead Transmission Line Considering the TEM‐Mode Formation Delay

When lightning strikes a transmission tower or overhead line, the lightning current generates a spherically expanding electromagnetic field. The propagation mode of an expanding electromagnetic wave is different from that of a transverse electromagnetic (TEM) wave, which is applied to the modeling of transmission lines. This paper presents an equivalent circuit model of an overhead transmission line that considers the TEM‐mode formation delay. The TEM‐mode formation delay is approximately represented by the first‐order delay functions in surge impedances and time delays in the mutual coupling from one line to the others. The proposed circuit model of the overhead line is introduced to the Alternative Transients Program version of Electromagnetic Transients Program using the MODELS language through a formulation in the phase domain based on Dommel's method. The results of the proposed model are validated through a comparison with the results of a three‐dimensional numerical electromagnetic analysis. Furthermore, the effect of the delay of the TEM‐mode formation on the voltages across the insulator strings of a lightning‐struck tower is described by referencing a previous experimental study conducted using an actual 500 kV transmission tower. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Optical trapping using transverse electromagnetic (TEM)-like mode in a coaxial nanowaveguide.

Optical traps have emerged as powerful tools for immobilizing and manipulating small particles in three dimensions. Fiber-based optical traps (FOTs) significantly simplify optical setup by creating trapping centers with single or multiple pieces of optical fibers. In addition, they inherit the flexibility and robustness of fiber-optic systems. However, trapping 10-nm-diameter nanoparticles (NPs) using FOTs remains challenging. In this study, we model a coaxial waveguide that works in the optical regime and supports a transverse electromagnetic (TEM)-like mode for NP trapping. Single NPs at waveguide front-end break the symmetry of TEM-like guided mode and lead to high transmission efficiency at far-field, thereby strongly altering light momentum and inducing a large-scale back-action on the particle. We demonstrate, via finite-difference time-domain (FDTD) simulations, that this FOT allows for trapping single 10-nm-diameter NPs at low power.

A tri-band mode conversion system for high-power microwave applications

To realize multi-band mode conversion in a high-power microwave incoherent power combination system, a tri-band conversion system (at X-, Ku-, and Ka-bands) is proposed in this paper. The tri-band conversion system mainly consists of three parts: a dual-band multiplexer, a circular waveguide with a 90° bend, and a tri-band mode converter. To investigate the mode coupling characteristics in the system, every part is carefully analyzed and verified. Numerical and simulation results show that the final conversion efficiencies of the conversion system are 98.9% [coaxial transverse electromagnetic (TEM) mode–coaxial TE11 mode at 10.16 GHz], 99.1% (coaxial TEM mode–coaxial TE11 mode at 14.45 GHz), and 99.6% (circular TM01–circular TE11 at 30.5 GHz). Meanwhile, its maximum power handling capacities reached 1.5 GW, 957.6 MW, and 726.2 MW. The good agreement between theoretical analyses and simulation results demonstrates that the proposed tri-band system is feasible in high-power microwave applications.

Modelling the Woven Structures with Inserted Conductive Yarns Coated with Magnetron Plasma and Testing Their Shielding Effectiveness

The paper proposes the analytic modelling of flexible textile shields made of fabrics with inserted conductive yarns and metallic plasma coating in order to calculate their electromagnetic shielding effectiveness (EMSE). This manufacturing process is highly innovative, since copper plasma coating improves EMSE on the fabrics with inserted conductive yarns of stainless steel and silver with 10–15 dB in the frequency range of 0.1–1000 MHz, as shown by the measured EMSE values determined according to the standard ASTM ES-07 via the Transverse Electromagnetic (TEM) cell. On the other hand, modelling of EMSE for such conductive flexible shields gives an insight on estimating EMSE in the design phase of manufacturing the shield, based on its geometric and electrical parameters. An analytic model was proposed based on the sum of EMSE of the fabric with inserted conductive yarns and EMSE of the copper coating. The measurement results show close values to the proposed analytic model, especially in case of fabric with conductive yarns having stainless steel content.

Analysis and Experimental Study of Radiative Microwave Pulses Effects on the Nonlinear Performance of a Low-Noise Amplifier

In this article, the performance of an unshielded low-noise amplifier (LNA), which is subjected to the incident high power microwave (HPM) pulse waves, is investigated analytically and experimentally. For this purpose, a time-domain algorithm is proposed, which uses the finite difference time domain (FDTD) method and a globally convergent iterative method to solve linear and nonlinear equations of the problem simultaneously. In particular, the effects of external incident electromagnetic (EM) field illumination with different types of waveforms, including HPM pulses and sinusoidal waves, on the nonlinear performance of a microwave LNA are investigated and discussed by this method. Furthermore, using a measurement setup comprised of a transverse EM (TEM) cell, the proposed method is validated by comparing with the measurement results in good agreement. The presented analysis would be useful in EM interference/compatibility (EMI/EMC) analysis, such as radiated susceptibility analysis of RF/microwave nonlinear circuits excited by the incident HPM pulse wave.

Low-cost Transverse Electromagnetic (TEM) cell design for radiated emission measurement

The increasing use of electronic and electrical equipment that continuously emits radiated emissions in the industrial, military, communications, household, and medical fields has increased dramatically over the past few decades. Radiated emission can interfere performance of other electronic devices around it. There is a demand for electric devices to comply with electromagnetic compatibility (EMC) standards before being marketed, requiring manufacturers to carry out EMC testing before devices enter the market. Transverse Electromagnetic (TEM) cells are usually used by designers to ensure that electronic devices comply with EMC standards. TEM cells for radiated emission measurement are widely used because they are cheap and time-saving before full compliance testing is carried out, which expensive for one-time screening. The main problems of commercial open TEM cells are relatively high price, weight, handling problems and portability. In this study, low-cost TEM cells were designed that could be used to test radiated emission generated by electronic devices. The fabricated TEM cells can operate up to 960 MHz and it can be used to test radiated emission generated from small electronic devices. It has better performance and more sensitive than branded TEM cells in the radiated emission test of a mobile phone.

An alternative method for field analysis in inhomogeneous domains

PurposeThis paper aims to solve inhomogeneous dielectric problems by matching boundary conditions at the interfaces among homogeneous subdomains. The capabilities of Hilbert transform computations are deeply investigated in the case of limited numbers of samples, and a refined model is presented by means of investigating accuracies in a case study with three subdomains.Design/methodology/approachThe accuracies, refined by Richardson extrapolation to zero error, are compared to finite element (FEM) and finite difference methods. The boundary matching procedures can be easily applied to the results of a previous Schwarz–Christoffel (SC) conformal mapping stage in SC + BC procedures, to cope with field singularities or with open boundary problems.FindingsThe proposed field computations are of general interest both for electrostatic and magnetostatic field analysis and optimization. They can be useful as comparison tools for FEM results or when severe field singularities can impair the accuracies of other methods.Research limitations/implicationsThis static field methodology, of course, can be used to analyse transverse electro magnetic (TEM) or quasi-TEM propagation modes. It is possible that, in some case, these may make a contribution to the analysis of axis symmetrical problems.Originality/valueThe most relevant result is the possible introduction of SC + BC computations as a standard tool for solving inhomogeneous dielectric field problems.

Bessel–Gauss Beam Launchers for Wireless Power Transfer

In this work, we study the use of Bessel–Gauss beam launchers for wireless power transfer (WPT) applications. The power transfer efficiency between two radiating apertures is investigated in the radiative near field. A spectral Green’s function approach is used to derive the power efficiency under a simultaneous conjugate impedance match. The transverse electromagnetic (TEM) mode of a coaxial cable, as well as Bessel beam (BB) and Bessel–Gauss beam (BGB) field distributions, are considered as aperture distributions. Numerical results demonstrate that a BGB field distribution is the optimal choice for WPT due to its limited spectrum and reduced diffraction of the radiated beam. We synthesized a Bessel–Gauss launcher that exhibits power efficiency exceeding 50% for distances larger than $30\lambda $ . These results show that non-diffracting beams can pave the way toward efficient near-field WPT systems with extended operating ranges.

Concept to Evaluate and Quantify Field Inhomogeneities in Coaxial TEM-Cells

The quality of a field probe calibration directly affects the uncertainty statement of radiated immunity tests. Therefore, precise field calibration is required. An often-used field generator is a transversal electromagnetic (TEM) cell. The IEEE Std 1309 provides three methods to calibrate a field probe. Method B, also known as the standard field method, uses a calculated reference field based on the geometry of the measurement environment and its input parameters. However, in reality, mechanical tolerances and misalignment can decrease the field quality. The results of the calculated model and the actual system may differ. Hence, this contribution proposes an approach for computing electromagnetic (EM) fields inside a TEM-cell considering mechanical tolerances and unknown input parameters. It is accomplished by projecting Maxwell’s equations onto eigenfunctions resulting in an infinite-dimensional differential equation system, the so-called generalized telegraphist’s equations (GTEs). Since this method starts with Maxwell’s equations, it can be used for a variety of applications. The proposed concept is applied on a coaxial TEM-cell with a circular cross-section with random imperfections. Based on the semi-analytical method and an input–output model for the uncertainty propagation, the combined uncertainty can be calculated following the guide to the expression of uncertainty in measurement (GUM).

Diverse surface waves supported by bianisotropic meta surfaces

Surface waves supported by structured metallic surfaces, i.e. metasurfaces, have drawn wide attention recently. They are promising for various applications ranging from integrated photonic circuits to imaging and bio-sensing in various frequency regimes. In this work, we show that surface states with diverse polarization configurations can be supported by a metasurface consisting of a single layer of bianisotropic metamaterial elements. The structure possesses D2d symmetry, which includes mirror symmetry in the xz and yz plane, and C2 rotational symmetry along y = +-x axis. Due to this unique symmetry, the metasuface supports both transverse electric (TE) and transverse magnetic (TM) waves along kx and ky directions, while a purely longitudinal mode and an elliptically polarized transverse electromagnetic (TEM) mode along ky = +-kx directions. The versatility of the surface modes on the metasurface may lead to new surface wave phenomena and device applications.

Fractional-Order Inductor: Design, Simulation, and Implementation

Fractional calculus has tremendous potential in modeling the evolution of complex systems including those with memory. Indeed, fractional-order models are more accurate in approximating non-locally distributed dynamics with short- or long-term memory effects. However, the realization of fractional systems is often hindered by the lack of robust fractional-order energy storage devices, particularly fractional-order inductors (FOIs). Inherent eddy currents, hysteresis losses, the lack of suitable materials, and a systematic design procedure are among the challenges of FOI synthesis. In this work, a straightforward and robust approach realizing FOIs with a coaxial structure is proposed. This approach relies on the fact that the wave impedance of the transverse electromagnetic (TEM) mode on the coaxial structure scales with $(\mathit {j}\omega)^{0.5}$ , where $\mathit {j}=\sqrt {(-1)}$ and $\omega $ is the angular frequency when the filling material is highly conductive. Indeed, experimental characterization of the realized device shows that it has a half-order inductive response (corresponding to 45° phase angle) that is stable in the frequency range 18 MHz – 1 GHz with a phase angle deviation not exceeding 5°. Furthermore, the effects of the device geometry and the permeability, the permittivity, the conductivity of the filling material on device response are investigated.

Reflection and Transmission Coefficients in Multilayered Fully Anisotropic Media Solved by Transfer Matrix Method With Plane Waves for Predicting Energy Transmission Course

In this article, we rapidly and accurately solve out reflection and transmission coefficients in the multilayered fully anisotropic media (MFAM) based on the transfer-matrix method (TMM) so that we could find out the energy transmission course (ETC) of plane waves that transmit through MFAM in the air background. Beginning with Maxwell's equations, MFAM's Helmholtz equation could be obtained by the known transverse- k vectors of plane waves. Through a series of complicated manipulations applied to the derivation of Helmholtz equations, we can attain ordinary differential equation of electric fields that merely exist in a certain direction and then compute four different eigenvalues in different MFAM regions. Under 3-D cases, meanwhile, concrete expressions of other fields can be obtained by given electric fields in the fixed direction. The ETC of electromagnetic fields in the tangential continuity is mainly considered in the TMM, and hence, the transferring matrix of electromagnetic field between MFAM regions can be constructed to achieve reflection and transmission coefficients. With various plane-wave modes such as transverse electromagnetic (TEM), transverse electric (TE), and transverse magnetic (TM) field modes, respectively, computational results of MFAM models are solved and adopted to compare with those from the commercial software of COMSOL. Finally, to discuss deeply and efficiently achieve color images, we acquire those reflection and transmission coefficients of more complicated fully anisotropic materials under the different transverse- k vectors. Our work can be an efficient and reliable solver for excavating prospective applications to predict ETC of models with single-layered/multilayered materials possessing fully anisotropy.