Huygens Surface Research Articles

In brief

PAGE 637 Researchers from a conglomerate of countries have improved the operation of passive optical networks. They present their work on an integrated transmitter and the receiver. Their work reports on the performance evaluation of a multi-channel transmitter that employs an arrayed reflective electro absorption photonic integrated circuit. With its low power consumption and small footprint it offers advantages compared with competing solutions. PAGE 648 In their Letter, a group from China propose an improved method for nearest level modulation(NLM) for cells of a cascaded H-bridge. The nearest level modulation directly controls the phase voltage of the converter and by optimising this H-bridge the system is improved. The H-bridge converter has high modulated accuracy and can improve the dynamic response speed and steady state accuracy of the control system. These devices could offer a low cost solution for the next generation of multiplexed passive optical networks PAGE 656 A Saudi-Indian partnership proposes a charge plasma based GaN MOSFET device that is free from hetero-epitaxial defects and inverse piezo electric effects making it more reliable. Hafnium with a work function of 3.9eV is used to induce n+ charge plasmas and create source and drain regions. An improved NLM for ten or so cells of cascaded H-bridge (CHB) converter with a high modulation precision is proposed PAGE 585 In this Letter, common mode radiation from cables attached to a printed circuit board (PCB) was predicted, with an accuracy of more than 95% observed for the upper bounds of the measured radiated emissions. Presented by a team from Malaysia, they modelled the expected radiation using the imbalance difference model. Computing the expected radiation before production helps to save time and cost. The charge plasma concept has been used first time in GaN devices PAGE 573 Researchers from France have used the Total-Field / Scattered-Field formulation method to compute an electromagnetic field far from its source. Computing the electromagnetic field can be difficult because of the numerical dispersion in large scale problems. Conventional approaches do not take into account 3D topography because of the amount of space and time needed; this new, simple, method allows the easy computation of 3D scattering. This work is important for circuit designers to predict the common mode radiated emissions from two cables attached to PCB The field radiated by a source is applied on a Huygen's surface in the surroundings of the scatterers

Radio-Frequency Interference Estimation Using Equivalent Dipole-Moment Models and Decomposition Method Based on Reciprocity

In modern electronic products, the noise from high-speed digital parts is likely to interfere with nearby receivers, causing radio-frequency interference (RFI) issues. In this paper, the equivalent dipole-moment models and a decomposition method based on reciprocity theory are proposed being used together to estimate the coupling from the noise source to the victim antennas. The dipole-moment models are extracted from the near fields of the noise source by solving the inverse problem. The tangential electromagnetic fields on a Huygens's surface, which enclose the victim antenna, can be calculated from these equivalent dipole-moment models. Then, the victim antenna only is treated as a radiator. The tangential electromagnetic fields from the radiating antenna on the same Huygens's surface can be obtained. With these two groups of the fields on the Huygens's surface, the reciprocity theory is applied to estimate the coupling from the noise source to the victim antenna. This method is validated by full-wave simulations and measurements of a simple printed circuit board. The proposed method provides convenience to estimate RFI issues in the early design stage and saves the time of RFI simulation and measurements.

Time-Domain Generalized Transition Matrix for Transient Scattering Analysis of Arrays

Time-domain generalized transition matrix (TD-GTM) based on the time-domain integral equations (TDIEs) is implemented in this letter. The TD-GTM is established on the reference Huygens surface that encloses the object, using the impulse responses obtained by the marching-on-in-time (MOT) solutions. The TD-GTM fulfills the domain decomposition of TDIEs naturally and flexibly. It allows us to analyze each module independently and then to solve the whole system by establishing the time-domain generalized surface integral equation (TD-GSIE). Various TDIEs are used to extract the TD-GTM for different modules. Numerical results show that the TD-GTM can effectively improve the efficiency of original TDIEs for transient scattering analysis of array structures.

Far-Field Prediction by Only Magnetic Near Fields on a Simplified Huygens's Surface

For radiation source locating above a ground plane, its far field can be predicted by only the magnetic near field through the method proposed in this paper. This method applies the finite element method to get the equivalent current sources from the tangential magnetic near fields. With the equivalent current sources, the far-field radiation can be calculated based on Huygens's principle and image theory. The magnetic near field is scanned on a Huygens's surface that encloses the source with its ground. In this paper, this Huygens's surface was first proposed as a five-surface cube on the ground. Then, the Huygens's surface was further simplified by using four lines instead of four side walls to make the proposed method easier in regards to practical near-field scanning. Several numerical examples were tested to validate the proposed method. In addition, the proposed method was validated experimentally by using a patch antenna. The performance of using only the top plane near fields was also investigated and discussed. By using only the magnetic near fields on the simplified Huygens's surface, the proposed method significantly saves measurement time and cost while also retaining good far-field prediction.

Numerical Analysis of Electromagnetic Fields in Multiscale Model* *Supported in part by China Postdoctoral Science Foundation under Grant No. 201M550839, and in part by the Key Research Program of the Chinese Academy of Sciences under Grant No. KGZD-EW-603

Modeling technique for electromagnetic fields excited by antennas is an important topic in computational electromagnetics, which is concerned with the numerical solution of Maxwell's equations. In this paper, a novel hybrid technique that combines method of moments (MoM) with finite-difference time-domain (FDTD) method is presented to handle the problem. This approach employed Huygen's principle to realize the hybridization of the two classical numerical algorithms. For wideband electromagnetic data, the interpolation scheme is used in the MoM based on the dyadic Green's function. On the other hand, with the help of equivalence principle, the scattered electric and magnetic fields on the Huygen's surface calculated by MoM are taken as the sources for FDTD. Therefore, the electromagnetic fields in the environment can be obtained by employing finite-difference time-domain method. Finally, numerical results show the validity of the proposed technique by analyzing two canonical samples.

Flame-Surface Advection in Transient Periodic Flow

The advection of an interface by a known transient periodic excitation flow is investigated in the present study, the results of which are relevant to the propagation of nearly isothermal premixed flames in turbulent flow. The relation between the corrugated-surface area and the intensity of the excitation flow is obtained numerically and compared with exact analytically derived solutions. The results elucidate the relation between the surface area and the intensity of spatial and temporal flow-field variations at low, moderate, and large intensities and highlight the stabilizing influence of Huygens surface propagation (e.g., of premixed flames) on the rate of surface-area increase, which is found to be otherwise unbounded in time.

Far-Field Prediction Using Only Magnetic Near-Field Scanning for EMI Test

Far-field prediction for electromagnetic interference (EMI) testing is achieved using only magnetic near-field on a Huygens's surface. The electrical field on the Huygens's surface is calculated from the magnetic near-field using the finite element method (FEM). Two examples are used to verify the proposed method. The first example uses the field radiated by an infinitesimal electric dipole. The calculated results are compared with the analytical solution. In the second example, the calculated results are compared with full-wave simulation results for the radiation of a print circuit board (PCB). The validity of this method when the near-field is high-impedance field is verified as well. Sensitivity of the far field to noise in both magnitude and phase in the near-field data is also investigated. The results indicate that the proposed method is very robust to the random variation of both. The effect of using only four sides of the Huygens's box is investigated as well, revealing that, in some instances, the incomplete Huygens's box can be used to predict the far field well. The proposed method is validated using near-field measurement data taken from a sleeve dipole antenna. The error for the maximum far-field value is in only 1.3 dB.

Polarization Control Using Tensor Huygens Surfaces

Controlling the polarization of the electromagnetic field is a crucial aspect of many communication and imaging systems. Building off of previous work on Huygens surfaces, which are surfaces used to manipulate wavefronts using electric and magnetic surface impedances, the concept of a tensor Huygens surface is introduced. A tensor Huygens surface consists of electric and magnetic surface impedances which are tensors as opposed to scalars. In this paper we show how the polarization can be modified from a given initial state to a desired state specifically using a tensor Huygens surface. We examine the fields at the surface to find the required impedance tensors to manipulate the polarization. We also come up with an equivalent circuit model which captures the behavior of the surface as well as its equivalent S-parameter representation. Furthermore, we examine how chiral functionality can be realized using two cascaded Huygens surfaces. We validate these results using a TLM solver as well. Finally, we demonstrate a possible implementation of a tensor Huygens surface made up of skewed dipoles and loops.

Transfer Function Method for Predicting the Emissions in a CISPR-25 Test-Setup

The CISPR-25 standard is used in the automotive industry to characterize the electromagnetic radiation of electronic components. The setup is comprised of an electronic device, a cable harness, a metallic table, and an antenna. Dimensions stretch from a couple of meters for the setup to fractions of a millimeter for printed circuit board features. Numerical prediction of radiated emissions (RE) is of great usefulness for prediction of potential electromagnetic compatibility nonconformities in the early design process, but extremely difficult to be done for this setup as a whole. In this paper, we demonstrate how RE can efficiently be computed based on a setup as commonly used to model conducted emissions only, i.e., electric control unit and harness on infinite-ground plane. Applying Huygens principle and using it to generate a fixed transfer function between a particularly chosen Huygens surface and the antenna, we arrive at a novel computing scheme for RE. The scheme is applied for the antenna model and antenna factor-based calculations and demonstrates agreement with measurements within 5 dB range.

A fast certified parametric near-field-to-far-field transformation technique for electrically large antenna arrays

This paper presents a fast certified numerical method for computing radiation patterns of electrically large antenna arrays over broad frequency bands and wide ranges of look angles. The suggested scheme combines finite-element analysis with empirical interpolation and employs a sub-domain approach on the Huygens surface to reduce computational costs in the offline part of the algorithm. To assure the reliability of the numerical results, an accurate and efficiently computable a posteriori error bound for the radiation patterns is proposed. A real-world example is presented to demonstrate the efficiency and accuracy of the suggested approach.

Efficient Plane Wave Excitation for 3-D Laguerre-Based FDTD Method

In the three-dimensional (3-D) Laguerre-based finite-difference time-domain method, each electric field variable has the relationship with the adjacent twelve electric fields. This results in the tedious modification of field components adjacent to the total-field/scatter-field boundary in analyzing scattering problems. In addition, the plane wave excitation requires much time in evaluating the expansion coefficient of incident field which involves integral of the weighted Laguerre polynomials with respect to time. In this letter, the plane wave is introduced by defining a set of equivalent currents on a closed Huygen's surface and a computationally efficient one-dimensional auxiliary propagator is presented to speed up the plane wave excitation. Numerical results indicated that the proposed method is valid.

Estimating Radio-Frequency Interference to an Antenna Due to Near-Field Coupling Using Decomposition Method Based on Reciprocity

In mixed radio-frequency (RF) and digital designs, noise from high-speed digital circuits can interfere with RF receivers, resulting in RF interference issues such as receiver desensitization. In this paper, an effective methodology is proposed to estimate the RF interference received by an antenna due to near-field coupling, which is one of the common noise-coupling mechanisms, using decomposition method based on reciprocity. In other words, the noise-coupling problem is divided into two steps. In the first step, the coupling from the noise source to a Huygens surface that encloses the antenna is studied, with the actual antenna structure removed, and the induced tangential electromagnetic fields due to the noise source on this surface are obtained. In the second step, the antenna itself with the same Huygens surface is studied. The antenna is treated as a transmitting one and the induced tangential electromagnetic fields on the surface are obtained. Then, the reciprocity theory is used and the noise power coupled to the antenna port in the original problem is estimated based on the results obtained in the two steps. The proposed methodology is validated through comparisons with full-wave simulations. It fits well with engineering practice, and is particularly suitable for prelayout wireless system design and planning.

Circuit Modeling of Huygens Surfaces

Huygens surfaces are a recently proposed way of manipulating electromagnetic wavefronts using a superposition of subwavelength electric and magnetic dipoles situated on a plane. This allows for interesting phenomena such as refraction, beam manipulation, and focusing using this planar screen. In this letter, a circuit model for the unit cells comprising a Huygens surface is proposed to further understand the functionality of this screen. The equivalent circuit is a lattice network whose constituent series and shunt impedances correspond to the impedances of the magnetic and electric dipoles, respectively. We demonstrate that the corresponding voltage and current terminal relations across the lattice network correspond exactly to the electromagnetic boundary conditions across the Huygens surfaces. We also show how this model can be used to design the required unit cells and, using a two-dimensional circuit solver, how these lattice cells can be used to model an entire Huygens surface.

An Iterative FDTD/MoM Technique for Assessing Coupling Effects in Front of Base-Station Antennas

In this study, we used an iterative numerical technique, which combines the finite-difference time-domain (FDTD) method with the method of moments (MoM), to investigate the coupling effect between a base-station antenna operating at 900 MHz and a worker in front of it. The numerical model of the antenna was a realistic representation of a commercially available array of dipoles, whereas for the worker a numerical phantom at 5 mm resolution, created from medical imaging of an adult male, was used. Rao-Wilton-Glisson (RWG) triangular elements were employed in the implementation of the MoM used to solve for the surface currents on the antenna structure. The total-field scattered-field formulation of FDTD was used in the computational domain, which contained the numerical phantom of the worker. An intermediate Huygens surface was introduced to establish an iterative procedure, which allowed us to calculate the influence of the human body on the radiating dipoles. It was found that using this iterative approach the whole body absorption near the antenna varied from the case when no coupling was considered.

A hybrid FDTD/SEM model for physics-oriented analysis of time-domain radiation properties of antenna-based sensors

A semi-analytical methodology is presented for the accurate analysis of time-domain radiation characteristics of antenna sensors. A locally conformal finite-difference time-domain technique is adopted to derive a minimal pole/residue spherical harmonic expansion of the equivalent currents excited on a suitable Huygens surface enclosing the sensing device. In this way, by using the singularity expansion method, the time-domain gain and effective height of the structure can be evaluated analytically, in terms of the newly introduced incomplete spherical Bessel functions, as the superposition of non-uniform spherical wave contributions attenuating along with the time and space according to the complex poles accounting for the natural resonant processes occurring in the device. The accuracy of the developed technique is assessed by application to an ultrawideband bow-tie antenna-based sensor for millimeter-wave radar measurements.

The Huygens surface science package (SSP): Flight performance review and lessons learned

The Surface Science Package (SSP) was one of six instruments flown onboard the Huygens probe to Titan, the largest moon of Saturn, in the framework of the NASA/ESA/ASI Cassini–Huygens mission (Matson et al., 2002). The SSP operated throughout the probe's descent and after landing on Titan on 14th January 2005. This paper reviews scientific results from the Surface Science Package, and also reports previously unpublished flight data which illustrate the performance of the measurement systems in the Titan environment.This review provides some lessons learned that may be useful for further detailed analysis of the Huygens mission data, and for payloads for future missions to Titan, in which there has been recent interest (e.g., the Titan Saturn System Mission (TSSM) (Joint TSSM Science Definition Team, 2009), TANDEM (Coustenis et al., 2009) or the Titan Mare Explorer (TiME) Discovery-class proposal (Stofan et al., 2010)), as well as for planetary probe missions more generally.

Implementation of the Huygens Absorbing Boundary Condition in Corner Regions

In recent years, three new absorbing boundary conditions (ABCs) have appeared in the literature, namely, the multiple absorbing surfaces, the reradiating boundary condition, and the Huygens ABC (HABC). The last is a generalization of the first two. The HABC mainly relies on the radiation of a field opposite to the outgoing field by means of surface currents. This paper focuses on the implementation of the HABC in the corner regions of computational domains. It is shown rigorously that the Huygens surface radiating the opposite field is not a normal Shelkunoff surface. Additional branches, called extensions, must be added in the corner regions.

Huygens' Principle for Complex Spheres

Huygens' relations that express wave fields of primary sources in terms of Huygens' sources on a spherical surface remain valid when the sphere radius is a complex number in a certain bounded domain. Such Huygens relations are derived for frequency and time-domain acoustic and electromagnetic fields. Interior and exterior source configurations are combined to obtain dual-sphere Huygens' relations, in which the primary sources are enclosed by one sphere and the observation points by another. The Huygens sources are complex point sources that exhibit directivity, which for certain parameter ranges makes it possible to achieve high accuracy with only a small fraction of the Huygens surface included in the integration. In general, for a dual-sphere configuration with fixed physical dimensions, the fraction of the spheres required to achieve a given accuracy diminishes with frequency, up to a certain frequency limit. Beyond this upper frequency limit the size of the required regions on the two spheres remain roughly constant. The upper frequency limit is increased when the imaginary part of the complex sphere radius is increased. A similar result holds in the time domain with respect to diminishing pulse width.

Bistatic scattering from three-dimensional target on perfectly conducting rough surface by using G-SMFSIA/CAG

This paper presents a novel and powerful numerical technique called general sparse-matrix flat-surface iterative approach-canonical grid (G-SMFSIA/CAG), which combines the sparse-matrix flat-surface iterative approach-canonical grid (SMFSIA/CAG) for 2D conducting rough surface and the method of moment (MoM) based on Rao-Wilton-Glisson (RWG) function for PEC target, to compute the electromagnetic scattering from a three-dimensional PEC target on conducting rough surface. The coupling surface integral equations (SIEs) for the composite model are derived based on Huygens surface equivalence principle. The SMFSIA/CAG is applied to solve the SIE of rough surface, and the targets’ SIE is solved using MoM. The iteration of SMFSIA/CAG and MoM takes account the interactions between target and the rough surface. Combining the PM(Pierson-Moskowitz)sea surface generated using Monte-Carlo method, the bistatic scattering coefficient for different targets on sea surface are computed. Convergence and effectivity of the G-SMFSIA/CAG is numerically validated. The bistatic scattering coefficient from ship on sea surface is calculated finally,and the dependence of bistatic scattering pattern upon the wind speed is discussed.

Unified Time- and Frequency-Domain Approach for Accurate Modeling of Electromagnetic Radiation Processes in Ultrawideband Antennas

A singularity-expansion-method-based methodology is proposed for the accurate time- and frequency-domain analysis and modeling of wave radiation processes in ultrawideband antennas. By means of this approach, the transient electromagnetic field distribution in the Fraunhofer region is presented in analytical closed form as the superposition of outgoing propagating non-uniform spherical waves. The time dependence of the wave amplitudes is determined by the resonant phenomena occurring in the structure. Analytical expressions for the antenna gain and effective height are derived. The major novelties of the presented formulation lie in a dedicated two-step vector fitting procedure for a minimal pole/residue spherical harmonic expansion of the time-domain equivalent electric and magnetic currents excited on a suitable spherical Huygens surface enclosing the antenna under analysis, as well as in the introduction of a new class of incomplete spherical Bessel functions useful to describe transient wave phenomena in truncated structures. The proposed approach is validated by application to an ultrawideband resistively loaded bow-tie antenna for ground-penetrating radar applications.