Avionics system design for high energy fields: A guide for the designer and airworthiness specialist

Because of the significant differences in transient susceptibility, the use of digital electronics in flight critical systems, and the reduced shielding effects of composite materials, there is a definite need to define pracitices which will minimize electromagnetic susceptibility, to investigate the operational environment, and to develop appropriate testing methods for flight critical systems. The design practices which will lead to reduced electromagnetic susceptibility of avionics systems in high energy fields is described. The levels of emission that can be anticipated from generic digital devices. It is assumed that as data processing equipment becomes an ever larger part of the avionics package, the construction methods of the data processing industry will increasingly carry over into aircraft. In Appendix 1 tentative revisions to RTCA DO-160B, Environmental Conditions and Test Procedures for Airborne Equipment, are presented. These revisions are intended to safeguard flight critical systems from the effects of high energy electromagnetic fields. A very extensive and useful bibliography on both electromagnetic compatibility and avionics issues is included

Gateway Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment

This document is a tailored version of MIL-STD-461, Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment, for the Gateway Program. While many of the requirements contained herein correspond with a MIL-STD-461 requirement, some are unique to the Gateway Program in order to meet the specific needs of the program. Nearly all limits are tailored specifically for Gateway elements, systems, and subsystems

Non-conventional sensors for measuring partial discharge under DC electrical stress

Partial discharge (PD) is a micro discharge that occurs in defected regions within the insulating media. As these discharges are the main culprits that cause dielectric material aging, PD measurements have been used for assessing insulating materials, including solids, liquids, and gases for power applications. There are various methods and sensors available for measuring PD sensitive to specific characteristics and operable over a wide range of frequencies. Most PD measurement techniques provide patterns that enable PD interpretation more comfortable for users. For example, in AC applications, the phase-resolved partial discharge (PRPD) technique provides identifiable patterns for distinguishing various types of PDs. However, the establishment of meaningful patterns to multiple types of PD in DC systems requires more sensitive and accurate measurements of individual PD pulses with noise rejection functionality due to the lack of phase-resolved information. Investigating of the transient phenomena such as individual PD pulses requires well-designed circuits with sufficiently large bandwidths. Waveshapes can be easily disturbed by background noise and deformed by the frequency response of measuring circuits and data acquisition systems (DAQ). Noises are unwanted disturbances that could be suppressed by suitable filters or mathematical methods. Measurement circuits and DAQ systems consist of transmission lines, sensors, cables, connectors, DAQ hardware, and oscilloscopes. Therefore, matching the impedance of all components guarantees a reflectionree path for traveling signals and addresses most of the challenges relevant to transient measurements. In this dissertation, we proposed and designed an appropriate testbed equipped with high bandwidth transmission line and electromagnetic field sensors suitable for investigating PD under DC electrical stresses. We comprehensively used finite element analysis simulations through the COMSOL Multiphysics software to design the dimensions and evaluate the frequency response of the testbed, transmission line, and electromagnetic sensors. Furthermore, based on the new testbed, DC PD measurements were performed using conventional and non-conventional sensors. Finally, various types of DC PD were statistically classified based on the proposed testbed

Radiation immunity in cable harnesses and differential P/N skew in PCB

We develop an efficient method to model RF immunity of multiwire cable harnesses and study differential P/N skew effects on channels, channel performance and specifically on the eye diagrams at the SerDes receiver. External radiation can induce unwanted signals in transmission lines. For example, external radiation from an antenna induces common-mode currents on the outer surface of cable shields. This common-mode signal makes its way through the shied due to its imperfections, inducing the inner common mode. When twisted pairs inside the cable are not balanced, inner common mode is in turn converted to the differential mode, which might compromise performance of sensitive electronics connected to the cable harness. In paper I, we develop the equivalent circuit model and the methodology for prediction of the worst-case envelope for differential mode signals induced in cable harnesses placed over a ground plane. The cable harness consists of twisted wires which are slightly unbalanced within the harness connector region. The induced signals are calculated using the transmission line theory avoiding the need for any 3D calculations. The results are validated by experimental measurements. Differential P/N skew is one of the main performance-limiting issue for high-speed SerDes links. The P/N skew is arrival time difference between two single-ended signals in a differential pair. It is commonly caused by unmatched delays of P/N lines of a differential pair but even for perfectly matched physical length cases, P/N skew can be caused by any other asymmetry between P/N lines. In the printed circuit board, relative location of fiber bundles with respect to conductors is random and results in uncontrolled P/N skew. In papers II, III, we derive analytical equations for S-parameters as a function of the P/N skew and frequency for weakly and strong coupled transmission lines. We also study the P/N skew effect on SerDes performance by measurements --Abstract, page v

A Method for Charactering EMI Coupling Paths and Source Properties in Complex Systems

A method for charactering EMI coupling paths in complex systems is presented. While it is relatively easy to determine the EMI antenna structures or the sources of EMI, it is often quite difficult to identify, and even more difficult to quantify coupling paths. This paper introduces a measurement-based method to quantify EMI coupling paths, and the source strengths can be indirectly determined by applying linear system theory. Circuit design guidelines, e.g., the permissible even-mode current in a differential signal, can be derived with the knowledge of the coupling path and EMI limits. Moreover, the EMI can be better predicted with the knowledge of the coupling paths, and the EMI source properties simulated with IBIS or SPICE circuit level simulations

Aircraft electromagnetic compatibility

Illustrated are aircraft architecture, electromagnetic interference environments, electromagnetic compatibility protection techniques, program specifications, tasks, and verification and validation procedures. The environment of 400 Hz power, electrical transients, and radio frequency fields are portrayed and related to thresholds of avionics electronics. Five layers of protection for avionics are defined. Recognition is given to some present day electromagnetic compatibility weaknesses and issues which serve to reemphasize the importance of EMC verification of equipment and parts, and their ultimate EMC validation on the aircraft. Proven standards of grounding, bonding, shielding, wiring, and packaging are laid out to help provide a foundation for a comprehensive approach to successful future aircraft design and an understanding of cost effective EMC in an aircraft setting

Design for Electromagnetic Compatibility--In a Nutshell

This open access book provides practicing electrical engineers and students a practical – and mathematically sound – introduction to the topic of electromagnetic compatibility (EMC). The author enables readers to understand better how to overcome commonly failed EMC tests for radiated emission, radiated immunity, and electrostatic discharge (ESD), while providing concrete EMC design guidelines. The book also presents an overview of EMC standards and regulations and how to test for a global market access

Contribution to the study of the vulnerability of critical systems to Intentional Electromagnetic Interference (IEMI)

The progress of high power electromagnetic (HPEM) sources during the late 1990s raised the concern in the electromagnetic compatibility (EMC) community that they could be deployed for criminal purposes to interfere with the operation of modern electronic systems. It is well established that sufficiently intense electromagnetic fields can cause upset or damage in electronic systems and therefore, can affect almost every critical infrastructure (CI) that is based on information and communication technologies (ICT). This field of study was initially known as electromagnetic terrorism, but was changed to the more encompassing term of intentional electromagnetic interference (IEMI). This thesis is a contribution to the assessment techniques of the vulnerability of CIs against IEMI. In order to quantify their impact, the electromagnetic environment created by IEMI sources needs to be characterized, the susceptible components and subsystems of the CIs should be identified, and the expected disturbances have to be evaluated. We present a qualitative methodology to carry out the so-called IEMI audit of a facility. Given the complexity of the problem, it was decided that the vulnerability of an infrastructure should be evaluated in a qualitative manner by regarding the consequences of interrupting the normal provision of a service, the probability of occurrence of an IEMI attack, and the preparedness of the infrastructure to withstand an attack. An updated survey and classification of potential IEMI sources that were collected from a large number of scientific publications is presented. The sources have been classified according to their electromagnetic environment, their transportability, technological development, and cost level. The expected disturbances due to a high frequency illumination of representative cabling systems inside an office were studied through measurements performed using a plastic raceway containing several types of cables found in commercial buildings. The tests revealed that at low and intermediate frequencies, low voltage power cables are more susceptible compared to telephone or network cables. At high frequencies, the coupling is dominated by connector apertures and discontinuities and load unbalance. The applicability of the TL theory in evaluating differential mode signals in two-wire lines floating above a ground plane was studied through comparisons with full-wave simulations. The results showed that the validity of the TL theory is conditioned upon an electrically short distance between the differential wires, regardless of the distances above the ground plane. TL theory is also used to assess the effect of conductive and dielectric losses in the dispersion of injected IEMI signals along power and communication cables as a function of the propagation length. A TL model of the low voltage power cabling of the plastic raceway was developed and in order to validate the models, the numerical results were compared against measurements obtained using frequency and time domain techniques. General considerations and guidelines for the application of the TL theory for evaluating the overall transfer impedance of complex cable assemblies are given. The obtained simulation results were found to be in good agreement with the experimental data up to frequencies of about 500 MHz. Finally, an improved model for estimating the transfer impedance of a two-layer braided shield is also proposed and validated using experimental data

Millimeter wave experiment for ATS-F

A detailed description of spaceborne equipment is provided. The equipment consists of two transmitters radiating signals at 20 and 30 GHz from either U.S. coverage horn antennas or a narrow beam parabolic antenna. Three modes of operation are provided: a continuous wave mode, a multitone mode in which nine spectral lines having 180 MHz separation and spaced symmetrically about each carrier, and a communications mode in which communications signals from the main spacecraft transponder are modulated on the two carriers. Detailed performance attained in the flight/prototype model of the equipment is presented both under laboratory conditions and under environmental extremes. Provisions made for ensuring reliability in space operation are described. Also described the bench test equipment developed for use with the experiment, and a summary of the new technology is included

La modélisation de l’immunité des circuits intégrés au-delà de 1 GHz

Electromagnetic Compatibility (EMC) is the faculty of working devices to co-exist electromagnetically. In practice, it turns out to be very complex to create electromagnetically compatible devices. The weapon to succeed the complex challenge of creating First-Time-Right (FTR) compatible devices is modelling. This thesis investigates whether it makes sense to model the conducted immunity of Integrated Circuits (ICs) beyond 1 GHz and how to do that. If the Printed Circuit Board (PCB) traces determine a PCB's radiated immunity, it is interesting to predict their coupling efficiency and to understand how that depends on the trace routing. Because full-wave solvers are slow and do not yield understanding, the existing Taylor cell model is modified to yield another 100 times speedup and an insightful upper bound, for vertically polarised, grazing-incident plane wave illumination of electrically long, multi-segment traces with arbitrary terminal loads. The results up to 20 GHz match with full-wave simulations to within 2.6 dB average absolute error and with Gigahertz Transverse Electromagnetic-cell (GTEM-cell) measurements to within 4.0 dB average absolute error. If the conducted immunity of ICs is interesting above 1 GHz, a measurement method is needed that is valid beyond 1 GHz. There is no standardised method yet, because with rising frequency, the common measurement set-up increasingly obscures the IC's immunity. An attempt to model and remove the set-up's impact on the measurement result proved difficult. Therefore, a simplified set-up and extraction method is proposed and a proof-of-concept of the automatic generation of the set-up's PCB is given. The conducted immunity of an LM7805 voltage regulator is measured up to 4.2 GHz to demonstrate the method. Except for a general trend of rising frequencies, there is only little concrete proof for the relevance of IC immunity modelling beyond 1 GHz. A full-wave simulation suggests that up to 10 GHz, most energy enters the die via the trace. Similarly, the radiated immunity of a microstrip trace and an LM7805 voltage regulator is predicted by concatenating the models developed above. Although this model neglects the radiated immunity of the IC itself, the prediction corresponds with GTEM-cell measurement to within 2.1 dB average absolute error. These experiments suggest the most radiation enters a PCB via its traces, well beyond 1 GHz, hence it is useful to model the conducted immunity of IC beyond 1 GHz. Therefore, the extension of IEC 62132-4 to 10 GHz should be seriously considered. Moreover, the speed and transparency of the modified Taylor model for field-to-trace coupling open up new possibilities for computer-aided design. The semi-automatic generation of lean extraction PCB could facilitate model extraction. There are also critical remaining questions, remaining to be answered.La compatibilité électromagnétique (CEM) est l'aptitude des produits électroniques à coexister au niveau électromagnétique. Dans la pratique, c'est une tâche très complexe que de concevoir des produits compatibles. L'arme permettant de concevoir des produits bon-du-premier-coup est la modélisation. Cette thèse étudie l'utilité et la faisabilité de la modélisation de l'immunité des circuits intégrés (CI) au-delà de 1 GHz. Si les pistes des circuits imprimés déterminent l'immunité rayonnée de ces circuits, il serait pertinent de pouvoir prévoir l'efficacité de couplage et de comprendre comment elle découle du routage des pistes. Les solveurs full-wave sont lents et ne contribuent pas à la compréhension. En conséquence, un modèle existant (la cellule de Taylor) est modifié de manière à ce que son temps de calcul soit divisé par 100. De plus, ce modèle modifié est capable de fournir une explication de la limite supérieure pour le couplage d'une onde plane, rasante et polarisée verticalement vers une piste de plusieurs segments, électriquement longue et avec des terminaisons arbitraires. Les résultats jusqu'à 20 GHz corrèlent avec des simulations fullwave à une erreur absolue moyenne de 2,6 dB près et avec des mesures en cellule GTEM (Gigahertz Transversale Electromagnétique) à une erreur absolue moyenne de 4,0 dB près. Si l'immunité conduite des CI est intéressante au-delà de 1 GHz, il faut une méthode de mesure, valable au-delà de 1 GHz. Actuellement, il n'y a pas de méthode normalisée, car la fréquence élevée fausse les observations faites avec la manipulation normalisée. Il est difficile de modéliser et de compenser le comportement de la manipulation normalisée. Par conséquent, une manipulation simplifiée et sa méthode d'extraction correspondante sont proposées, ainsi qu'une démonstration du principe de génération automatique de la carte d'essai utilisée dans la manipulation simplifiée. Pour illustrer la méthode simplifiée, l'immunité conduite d'un régulateur de tension LM7805 est mesurée jusqu'à 4,2 GHz. À part la tendance générale des fréquences qui montent, il y a peu de preuve concrète qui étaye la pertinence de la modélisation de l'immunité conduite des CI au-delà de 1 GHz. Une simulation full-wave suggère que jusqu'à 10 GHz, la plus grande partie de l'énergie rentre dans la puce à travers la piste. Par concaténation des modèles développés ci-dessus, l'immunité rayonnée d'une piste micro-ruban et d'un régulateur de tension LM7805 est prédite. Bien que ce modèle néglige l'immunité rayonnée du CI lui-même, la prédiction corrèle avec des mesures en cellule GTEM à une erreur absolue de 2,1 dB en moyenne. Ces expériences suggèrent que la plus grande partie du rayonnement entre dans un circuit imprimé à travers ses pistes, bien au-delà de 1 GHz. Dans ce cas, la modélisation de l'immunité conduite au-delà de 1 GHz serait utile. Par conséquent, l'extension jusqu'à 10 GHz de la méthode de mesure CEI 62132-4 devrait être considérée. De plus, la vitesse et la transparence du modèle de Taylor modifié pour le couplage champ-à-ligne permettent des innovations dans la conception assistée par l'ordinateur. La génération semiautomatique des cartes d'essais dites maigres pourrait faciliter l'extraction des modèles. Certaines questions critiques et importantes demeurent ouvertes