Introduction The three top product failures I see constantly in my consulting practice are (1) radiated emissions, (2) radiated susceptibility, and (3) electrostatic discharge. After reviewing and testing hundreds of products over the years, I’ve come to the conclusion that products fail these tests for five common reasons (somewhat in order of incidence); PC Board … [Read more...]
EMI Pre-Compliance Testing
Introduction This article describes how I perform pre-compliance testing for the top four EMI issues I constantly run into; conducted emissions, radiated emissions, radiated immunity, and electrostatic discharge. Of these, the last three are the most prevalent issues, with radiated emissions typically being the biggest compliance challenge during certification testing. If … [Read more...]
Review of MIL-STD-1275 Requirements
Introduction This may seem disassociated from the electromagnetic compatibility (EMC) theme of this publication but issues dealing with power quality and the qualification testing has a direct link to EMC. Frequently the EMC engineers and technicians are tasked taking care of the power quality, so I believe that reviews of these standards are appropriate. MIL-STD-1275 deals … [Read more...]
New and Proposed Changes to CISPR SC I Standards
Are you familiar with CISPR 32 and CISPR 35? CISPR 32 was originally published in 2012, followed by a pair of corrigenda and then the 2nd edition was published in 2015. CISPR 32 replaced CISPR 13 (Broadcast receivers emissions) and CISPR 22 (ITE emissions), both of which were withdrawn by the IEC on March 5, 2017. In the EU CISPR 32 is published as EN 55032 and it has … [Read more...]
Ten Tips to Minimize EMI from On-Board DC-DC Converters
It is fairly common to find multiple onboard DC-DC converters on today's portable, mobile, and IoT devices. If the device uses wireless, GPS, or cellular technologies, the EMI from these converters (which generally use switching frequencies between 1 and 3 MHz) often interferes with the receiver performance of the wireless modules. The problem really crops up for low-band … [Read more...]
Updated 52-Page Catalog of EMI/RFI Shielding Solutions
Plymouth, MA.... Available in both interactive PDF and printed versions, the 2018 catalog details all standard and custom EMI/RFI shielding product options. The PDF format lets the user click to download interactive sales drawings on over 150 products, including finger stock profiles, metalized fabric gaskets, fan vents, and board level shielding. The Table of Contents, Part … [Read more...]
Basic EMI Concepts
Understanding EMC is all about two important concepts: (1) all currents flow in loops and (2) high frequency signals are propagated as electromagnetic waves in transmission lines and the field energy travels through the dielectric. The two concepts are related because they are intertwined together. Digital signals create the propagating field, which induces the convection … [Read more...]
Proposed Changes to CISPR SC I Standards
Are you familiar with CISPR 32 and CISPR 35? CISPR 32 was originally published in 2012, followed by a pair of corrigenda and then the 2nd edition was published in 2015. CISPR 32 replaced CISPR 13 (Broadcast receivers emissions) and CISPR 22 (ITE emissions). In the EU CISPR 32 is published as EN 55032 and it has superseded EN 55013 and EN 55022. By now you should all be … [Read more...]
Silicon-Based EMI Gasket Material FDA Approved for Medical Products
Specialty Silicone Products (SSP) supplies medical grade platinum-cured silicones in durometers ranging from 10 to 80 (Shore A). These ultra-clean, high-purity silicones are part of the SSP-2390 series and meet stringent FDA CFR 177.2600, USP Class VI, and RoHS requirements. SSP’s medical grade platinum-cured silicones are normally translucent but can be supplied in custom … [Read more...]
Measuring Cable Resonance with a Comb Generator
by Kenneth Wyatt Cables are one of the key metallic structures on a product that can act as an antenna and couple energy, causing radiated emissions and possible compliance test failures. This has been discussed extensively in the literature on product design for EMI compliance. In many cases, they can resonate at their half-wave frequency and actually amplify any harmonic … [Read more...]
