The Commission of the European Union (EU) has published an updated list of standards that can be used to demonstrate conformity with the essential requirements of the EU’s directive on electromagnetic compatibi... Read More...
Military EMC design can be particularly vexing. Multiple environments combined with multiple threats lead to multiple requirements. The threat levels, and the resulting requirements, are usually more stringent than found in the commercial world.
AUTHOR’S NOTE Due to problems in the digital publishing process, MIL‑STD‑464B 01 October 2010 is scrapped and MIL‑STD‑464C, release date 01 December 2010 will take its place. There are no technical changes f... Read More...
LATE-BREAKING NEWS UPDATE!
Due to problems in the digital publishing process, MIL-STD-464B 01 October 2010 is scrapped and MIL-STD-464C, release date 01 December 2010 will take its place. There are no technical changes from what are described in this three part article, but the replacement for MIL-STD-464A will be MIL-STD-464C. MIL-STD-464B dated 01 October 2010 will cease to exist.
The science of electromagnetic compatibility has been in existence for several decades. As an art, it goes back much further, perhaps to the time of Edison when he was just beginning to experiment with practical electrical devices. I am sure that with some of his more sophisticated devices undesired interactions took place because of inadequate shielding or filtering. Certainly, with the advent of radio, incompatibility problems occurred as a result of the poor quality of transmitters and receivers. Perhaps the first formal recognition of electromagnetic compatibility problems occurred when the telephone and power companies found they had mutual coupling problems when their lines were carried on the same utility poles. Later on, the increasing use of the radio spectrum called for formal controls administered by departments in the post, telephone, and telegraph offices in many countries, or through the Federal Communications Commission in the United States.
A discussion topic between designers, namely those who only do circuit design and have no interest in the field of EMC, and compliance engineers attempting to meet regulatory compliance requirements, is the use of FR-4 as the core material for printed circuit board construction. Fiberglass Resin (FR) is low cost and has been used in almost every electrical product for decades, with exceptions such as military and satellite applications, harsh environmental conditions, and other unique uses. The disagreement lies with the extent that we can use FR-4 in high frequency applications and should we be concerned more with electrical performance or manufacturing and assembly.
The railway environment is generally regarded as a “severe” electromagnetic environment. For an electrified railway, Megawatts of power are required to be converted into the propulsion of trains in order to transport passengers or freight from one destination to another. The railway presents a complex electromagnetic environment made up of many systems including signalling, traction, telecommunications and radiocommunications.
Two of the more important publications in the area of Electromagnetic Compatibility (EMC) and Measurement Uncertainty (MU) are LAB 34 and CISPR 16-4-2. EMC and Measurement Uncertainty are receiving more attention as other CISPR Product Family Standards begin to adopt MU. LAB 34 is “The Expression of Uncertainty in EMC Testing” and is published by the United Kingdom Accreditation Service (UKAS). CISPR 16-4-2 is published by the International Electrotechnical Commission (IEC) and is titled “Specification for Radio Disturbance and Immunity Measuring Apparatus and Methods – Part 4-2: Uncertainties, Statistics, and Limit Modeling – Uncertainty in EMC Measurements.” This article compares and contrasts the two MU documents.
Do you supply products into Europe? If you supply products that come within the scope of the EMC Directive 2004/108/EC, the application of harmonized standards provides the simplest means of demonstrating conformity with the protection requirements (emission and immunity) of the Directive.
This article will provide you with essential information on the selection and use of the appropriate standards for your product.