Tungsten carbide/aluminum composite particles inhibit galvanic corrosion of aluminum. Harry Fuerhaupter, Potters Industries, Inc. ABSTRACT An ongoing issue in the design of reliable EMC shielding is galvanic corrosion of aluminum. How can an aluminum frame be protected from galvanic corrosion if it contacts an EMI gasket containing non-aluminum particles? Chromate conversion … [Read more...]
Crucial RF Shielding Selection Considerations
Gary Fenical Laird Technologies INTRODUCTION Designers must attenuate RF signals for various reasons. Since a product cannot be legally marketed unless it meets EMC requirements, designers must curtail RF signals above a certain limit. It is important to consider RF shielding materials at the beginning of a design project because choosing the correct kind of shielding upfront … [Read more...]
Understanding Shielding Effectiveness of Materials and Measurements in the Near-Field and Far-Field
When we treat the shielding effectiveness measurement with a uniform field, the results are similar for both near and far fields. Kermit O. Phipps and Philip F. Keebler EPRI EMC Laboratory, Knoxville, TN, USA INTRODUCTION Traditionally Schelkunoff’s shielding effectiveness equation is used universally in teaching and practice throughout the EMC community as a whole. In this … [Read more...]
Magnetic Shielding Design for Manufacturing
Sensitive electronic devices require protection from radiating magnetic fields. David Grilli Magnetic Shield Corporation, Bensenville, IL, USA Magnetic shielding for static and low frequency (<100 kHz), time-varying magnetic fields is accomplished by containing a specific device or item within a sheet metal enclosure of high permeability material. Typically, a sensitive … [Read more...]
Designing an RF Shielded Enclosure
Ron Brewer EMC/ESD Consultant Shielding has been with us a long long time. Early AM radios had shielded RF and IF transformers, shielded electron tubes, and compartmentalized shielded chassis. These shields were necessary to prevent RF pickup, feedback, and oscillation by the electron tubes, radiation from the local oscillator, RF contamination of the IF strip, and crosstalk … [Read more...]
A Second Look at the FCC Dynamic Frequency Selection Certification Issues
Both manufacturers and test labs must decide on the proper test procedures for DFS products. Since July 20, 2006, systems operating under FCC Part 15.407, specifically in the 5250- to 5350-MHz and the 5470- to 5725-MHz bands, are required to support Dynamic Frequency Selection (DFS) before the products can be certified. As part of the approval process, the FCC must carry out a … [Read more...]
Managing & Planning the EMC of MOTS and COTS Used Within MOD Systems & Platforms
Defense contractors intending to supply military off-the-shelf (MOTS) and/or commercial off-the-shelf (COTS) electrical/electronic equipment for use on UK military platforms, or to integrate them into UK military systems now have new guidance on a risk assessment process for achieving electromagnetic compatibility (EMC). Pete Dorey, senior EMC consultant at TUV Product Services … [Read more...]
Solving the Galvanic Corrosion Issue in EMI Shielding
Tungsten carbide/aluminum composite particles inhibit galvanic corrosion of aluminum. An on-going issue in the design of reliable EMC shielding is galvanic corrosion of aluminum. How can an aluminum frame be protected from galvanic corrosion if it contacts an EMI gasket containing non-aluminum particles? Chromate conversion coatings have long been used to reduce the corrosion … [Read more...]
Off-Chip Decoupling Measures: The EMC Perspective
Off-chip decoupling, or buffering, is a necessity. Over the years, many papers and articles have been written about optimizing off -chip IC decoupling. Many IC vendor application recommendations feature a cluster of decoupling capacitors adjacent to the IC, in close proximity to one another—viz. an electrolytic capacitor along with a small and a large value ceramic capacitor … [Read more...]
