Dario Negrini Leader Tech Inc. Tampa, FL Let's face it. If you didn’t have to worry about EMI shielding issues with your circuit board, life would be much simpler. Unfortunately, as product designs continue to shrink in size and as the list of features continues to grow, EMI compliance issues cannot be overlooked. Circuit board shields are one of the best ways to … [Read more...]
Shielding
Concerning Exposure of Workers and the General Public to Electromagnetic Fields
Keith G. Richens Cranage EMC & Safety Oakley, Shropshire, UK Introduction Electromagnetic fields (EMF) are universally present in the everyday environment, including workplaces and public areas. Measurements are made to identify and characterise them to ensure that people are not exposed to fields that could potentially cause injury or adversely affect … [Read more...]
Using A Transmission Line Model To Analyze Shield Current Distribution Resulting From Bulk Current Injection (BCI)
Arthur J. Glazar, Life Senior Member IEEE Background Radio frequency (RF) signal energy is normally confined to the interior of a coaxial cable. RF currents on the surface of a cable shield are undesirable and generally indicate a problem. Shield surface currents can occur as the result of conducted susceptibility (CS) or radiated susceptibility (RS). Whatever their … [Read more...]
Stability of Nickel-Graphite Conductive Filler in Silicone Elastomer for EMI Shielding Applications
How does aging affect the shielding effectiveness of a gasket? Brian W. Callen, Ph.D. and Claudia E. Johnston Sulzer Metco (Canada) Inc., Fort Saskatchewan, Alberta, Canada Nickel graphite conductive fillers have been replacing conventional silver-based fillers in EMI shielding gasket materials. Filled elastomer shielding gaskets include extrusions, molded shapes, die cut … [Read more...]
EMC Management and Design in Military and Aerospace Systems—Avoiding the Pitfalls
A systematic approach to EMC engineering and management is the best way of achieving compliance. A.S. De Beer, Ph.D Ruphus Technologies (Pty) Ltd., Lonehill, South Africa ABSTRACT This article focuses on the necessity of following a systematic engineering approach in the design and testing of military and aerospace systems that must comply with stringent EMC Standards. It … [Read more...]
Optimizing EMI Filters Using Circuit Simulation
Simulation saves time, money, and effort in resolving EMI problems in any application. Chris Debraal Curtis Industries Milwaukee, WI The insertion loss of a power line EMI filter can be accurately predicted over a wide range of frequencies through circuit simulation. While analyzing the circuit, it is important to consider test modes and impedances, basic component values, … [Read more...]
EMC Pre-testing Simplifies NEBS Compliance
Introduction NEBS was developed by Bell Labs in the 1970s to standardize equipment that would eventually be installed in a phone company's central office (CO). Sorting out the acronyms, NEBS stands for "Network Equipment-Building System," a term used to describe the environment of a typical Regional Bell Operating Company (RBOC). To get a basic understanding of NEBS, visit … [Read more...]
HIRF Testing in an Anechoic Chamber
A detailed examination of radiated field and transmitted power test techniques MICHEL LE CLECH, EMITECH ABSTRACT HIGH PULSED E-FIELD TEST LEVELS increased at the end of the 1990s. At the same time, many efforts were made to develop a very efficient test technique with the mode-stirred chamber. However, by improving the antenna design and test distances, comparable levels can … [Read more...]
Reflections on Absorbers
High frequency, broadband performance links recent improvements in EMI shielding components Jim May, Ferrishield, Inc., Scranton, PA, USA Just as the electronics industry has experienced exponential change over the past decades, EMI shielding components have undergone vast changes and improvements. Just ten years ago, many of today's widely-used gaskets, filters, ferrites, … [Read more...]
Aspects of Conductive Filler Loading on EMI Shielding and DC Volume Resistivity
Brian W. Callen, B. Sc., Ph.D. and Claudia E. Johnston Westaim Ambeon, Fort Saskatchewan, Alberta, Canada Dennis K. Morland, P. Eng., M.Sc. The Northern Alberta Institute of Technology, Edmonton, Alberta, Canada INTRODUCTION Conductive fillers for plastics have been used in EMI shielding applications for many years. Initially pure metallic powders such as nickel or copper … [Read more...]