Francescaromana Maradei

Field analysis of penetrable conductive shields by the finite-difference time-domain method with impedance network boundary conditions (INBCs)

Impedance network boundary conditions (INBCs) are implemented in the finite-difference time-domain (FDTD) method to analyze the electromagnetic field around penetrable shield structures. The shield region is eliminated from the computational domain and the INBCs are applied on the new boundary surfaces, i.e., shield surfaces, to take into account the field discontinuity produced by the shield. The INBCs represent an important extension of the well-known surface impedance boundary conditions (SIBCs) since the INBCs model accurately the coupling of the electromagnetic fields through penetrable shields and lead to a significant reduction of the number of the FDTD unknowns. The INBC expressions are given analytically in both frequency and time domains, and the INBC implementation in a FDTD code is discussed. The proposed INBC-FDTD method is numerically efficient because the resulting convolution integrals are recursively solved. Furthermore, approximate time-constant INBCs are proposed which are valid for many practical applications. The analysis of transient electromagnetic fields around penetrable conductive shields in simple test configurations are presented and compared with the analytical solutions.

Signal Integrity and Radiated Emission of High-Speed Digital Systems

Before putting digital systems for information technology or telecommunication applications on the market, an essential requirement is to perform tests in order to comply with the limits of radiated emission imposed by the standards. This book provides an investigation into signal integrity (SI) and electromagnetic interference (EMI) problems. Topics such as reflections, crosstalk, switching noise and radiated emission (RE) in high-speed digital systems are covered, which are essential for IT and telecoms applications. The highly important topic of modelling is covered which can reduce costs by enabling simulation data to demonstrate that a product meets design specifications and regulatory limits. According to the new European EMC directive, this can help to avoid the expensive use of large semi-anechoic chambers or open area test sites for radiated emission assessments. Following a short introduction to signalling and radiated interference in digital systems, the book provides a detailed characterization of logic families in terms of static and dynamic characteristic useful for modelling techniques. Crosstalk in multi-coupled line structures are investigated by analytical, graphical and circuit-based methods, and techniques to mitigate these phenomena are provided. Grounding, filtering and shielding with multilayer PCBs are also examined and design rules given. Written by authors with extensive experience in industry and academia. Explains basic conceptual problems from a theoretical and practical point of view by using numerous measurements and simulations. Presents models for mathematical and SPICE-like circuit simulators. Provides examples of using full-wave codes for SI and RE investigations. Companion website containing lists of codes and sample material. Signal Integrity and Radiated Emission of High-Speed Digital Systems is a valuable resource to industrial designers of information technology, telecommunication equipment and automation equipment as well as to development engineers. It will also be of interest to managers and designers of consumer electronics, and researchers in electronics.

Circuit and Numerical Modeling of Electrostatic Discharge Generators

The paper provides two accurate and efficient models of electrostatic discharge (ESD) generators which permit to reproduce the discharge current in the contact mode taking into account the load effect. The first model is based on a circuit approach and is suitable to be implemented in any commercial circuit simulator. The second model is based on the numerical solution of the field equations by using the commercial numerical code microwave studio (MWS) based on the finite integration technique. The validation of the proposed circuit and numerical models is carried out by comparison with measurements.

Axial-Flux Permanent-Magnet Generator for Induction Heating Gensets

This paper presents a single-phase slotless axial-flux permanent-magnet synchronous machine for induction heating gensets. A full-scale prototype of the machine (110 kVA, 400 Hz, 690 A) has been designed and subsequently analyzed through finite element analysis (FEA). Induced current distributions in the permanent magnets and in the rotors have also been calculated through FEA, showing that the resulting losses are kept at bay due to the low armature reaction. An effective way of achieving regulation of the power transferred to the load has been analytically derived. The prototype has also been built, and experimental tests confirm the aforesaid analyses.

SPICE-like models for the analysis of the conducted and radiated immunity of shielded cables

The aim of this work is the development and validation of compact SPICE models suitable to analyze the conducted and radiated immunity of shielded cables. The reference structures are coaxial cables, and shielded cables with two parallel wires (i.e., twinax cable). The conducted and radiated immunity of the shielded cables are evaluated considering as source a known injected current on the cable shield, and the coupling with an external plane wave electromagnetic field, respectively. The circuit models are validated by comparing the results with those obtained by other approaches. The developed models are then used to quantify the main grounding practices of shielded cables.

Circuital and numerical modeling of electrostatic discharge generators

This paper provides two accurate and efficient models of electrostatic discharge generators which permit to reproduce the discharge current in the contact mode, taking into account the load effect. The first model is based on a circuit approach and is suitable to be implemented in any commercial circuit simulator. The second model is based on the numerical solution of the field equations by using the commercial numerical-code microwave studio based on the finite-integration technique. The validation of the proposed circuit and numerical models is carried out by comparison with measurements

Safety Assessment of UWB Radio Systems for Body Area Network by the

The paper deals with the numerical prediction of the specific absorption (SA) of ultra wideband (UWB) radio systems for wireless body area network (BAN). The electro-magnetic analysis is performed by a frequency-dependent finite difference time domain (FD2TD) method here proposed with a new formulation based on a total current density approach. A first order Debye approximation is used to model the frequency-dependent properties of the human body in the frequency range of the UWB signals. The proposed method permits to assess the specific absorption and power loss in the human body exposed to an UWB pulsed source. Different numerical models of the human bodies are finally considered in order to investigate safety aspects.

{\rm FD}^{2}{\rm TD}

A general circuit-oriented, full-wave, finite-element method (FEM) is proposed to analyze the coupled problem between circuits and fields both in frequency and in time domains. The electromagnetic field problem is modeled by an equivalent electrical network obtained by the Whitney finite-element equations. The presence of circuit components in the field domain is easily taken into account introducing the lumped circuit components directly in the field equivalent electrical network. Simple test configurations are analyzed by a CAD circuit simulator to show the performances of the proposed circuit-oriented method.

Method

A frequency dependent Whytney-element time-domain (WETD) method is proposed for the calculation of the interaction between transient electromagnetic fields and frequency dependent materials. The proposed formulation is efficient since recursive convolution techniques are applied for the time domain implementation of the dispersive material characteristic. The method is suitable for the computation of the transient response in biological tissues, water and plasmas excited by pulse electromagnetic sources.

Circuit-oriented FEM: solution of circuit-field coupled problems by circuit equations

This paper describes the evaluation of electric and magnetic fields due to electrostatic discharges (ESDs) using an efficient numerical prediction model and measurements obtained with simple field sensors. The numerical prediction model is implemented using software based on the finite integration technique (FIT). The ESD generator is efficiently modeled, and the contact-mode discharge current is well reproduced taking into account the loading effect of the generator. Simple free-space field sensors are effectively used to measure the fields from an ESD event. Suitable numerical and theoretical characterizations of these sensors are proposed to derive a sensor transfer function that permits the fields to be reconstructed from the measured voltage. The numerical characterization is performed by Microwave Studio (MWS), while the theoretical characterization is based on lumped element circuit models of the sensors. The validation of both the proposed procedures indicates good accuracy up to 2 GHz as required by the International Electrotechnical Commission standard for ESD measurements.