Basic Parameters of the Normalized Site Attenuation (NSA) Method for Open Area Test Sites (OATS) and Semi Anechoic Chambers (SAC) in CISPR 16‑1‑4


This article is intended to provide an understanding of the requirements for qualification of either an open area test site (OATS), semi anechoic chamber, or fully anechoic room for use in the measurement of radiated disturbances in the frequency range of 30 MHz to 1 GHz. This is referred to as normalized site attenuation (NSA) testing, as described in CISPR 16‑1‑4. Qualification of these compliance test sites in the frequency range from 1‑18 GHz, commonly referred to as site voltage standing wave ratio (sVSWR) testing, will be covered in a future article.


In order to provide the technical parameters for verification of these compliance test sites, let’s review a few of the fundamentals of the EMC standard process. CISPR is the abbreviation for the Comité International Spécial des Perturbations Radioélectriques (English translation: International Special Committee on Radio Interference), which is a part of the International Electrotechnical Commission (IEC). As most of us in the EMC industry know, the IEC is an international organization, of which the U.S. is a member, with committees and subcommittees that focus on the research and development of standards that cover areas like Product Safety, EMC and mechanical hazards. These standards are often adopted by the European Union in the form of EN (the abbreviation for the French words “Norme European,” or European Standard), as well as in other jurisdictions around the world.

To read the full article by Lou Feudi, please visit the InCompliance Magazine digital edition.