Content on this page requires a newer version of Adobe Flash Player.

Adobe Flash Player

Technology-Focused Library

Product name: Electromagnetic Wave Anechoic Chambers / Electromagnetic Wave Absorbers

Ever since we developed the world’s first electromagnetic wave anechoic chamber with Composite type (so called Hybrid type) ferrite electromagnetic wave absorber in 1969, TDK’s electromagnetic wave anechoic chambers have been responding to the high expectations and advanced demands from numerous public and private corporations which aspire to next-generation technologies.

Needs for EMC measurement have been changing and becoming more sophisticated as electronics technologies evolve.


  • Smaller, more efficient, longer life electromagnetic wave absorber
  • Robust framework design and safety construction management
  • Operator friendly circumstances such as brightness, cleanliness and acoustics
  • Reinforced reliability and rational, efficient designs of doors and ancillary facilities
  • Dedicated/maintenance service system established such as periodic inspection, annual maintenance contract system
  • Expanded technical support system for diverse measurement needs

TDK has examined, explored, and carefully improved the “conditions” of electromagnetic wave anechoic chambers which adequately satisfy the requirements at the forefront of the times our electromagnetic wave anechoic chambers have been developed through these rigorous efforts, and more than 1100 sites* have been installed worldwide. *As of January 2012


Global map of the construction track record

The achievement is just one of our many developments. For device designers who seek ideal EMC circuit design essential for electronics development, electromagnetic wave anechoic chambers with even better performance and a more comfortable measurement environment, and measurement systems with extended rationality and efficiency are necessary.

To support these efforts in a steady and detailed fashion, we will do our best to reinforce your strategic endeavors by further improving the characteristics/performance, upgrading design/constructing processes, innovating device development environment of the “World standard electromagnetic wave anechoic chambers”, for which we have received admiration and acclamation from countless customers.

Title of the text: Our efforts toward realizing alternatives to CALTS (Calibration Test Site) / Next-generation 10m Test Range electromagnetic wave anechoic chamber

Realizing the similar performance of an Open Area Test Sites (OATS) in the anechoic chambers

OATS which are constructed in a distant location for optimal electromagnetic environment pose the inevitable limitations in accelerating and streamlining EMI measurements, being susceptible to weather conditions, and time-consuming when transporting equipment and personnel.

But OATS with a small deviation, within ±1dB, which is a requirement of CALTS, play an imperative role as a site for antenna calibration and as a traceability standard site which guarantees the reliability of EMI measurement of the 3m Test Range and 10m Test Range electromagnetic wave anechoic chambers.

Image of the open site

But there have been unavoidable changes in electromagnetic environment near the OATS around the globe as mobile phones and many kinds of wireless telecommunication programs rapidly evolve and expand (A growing number of areas can no longer maintain the required deviation for CALTS due to terrestrial digital television broadcasting). Even at an OATS in which high-precision EMI measurement is available, immunity tests with intense electric field radiation can not be performed due to radio wave codes and regulations of the countries in which the site is located.

Given the changes in electromagnetic environment and limitations in rationalized measurement, an electromagnetic wave anechoic chamber with a similar electromagnetic environment to that of CALTS standard OATS with a deviation within ±1dB, that is, performance required to be an alternative to CALTS specification/standard OATS, has been much sought after.

The 10m Test Range electromagnetic wave anechoic chamber supports the approach to developing next-generation devices in an accelerated and cost-saving measurement.

The latest version of hybrid type electromagnetic wave absorber 2.5m high IP-250BL

The 10m Test Range electromagnetic wave anechoic chamber promises site performance which satisfies the CALTS conditions a highly anticipated electromagnetic environment by many enginerrs worldwide.

The chamber alone can of course provide a high-efficiency measurement/development environment. But adding one to the apex of traceability with the conventional measurement facilities, such as 3m Test Range anechoic chambers, permits construction of EMI/EMS measurement systems that overcome the issues regarding the OATS and limitations in measurement efficiency with superior reliability as good as that of CALTS specification of the OATS.

Next-generation 10m-method electromagnetic wave anechoic chamber

The latest version of Hybrid type absorber 2.5m high IP-250BL which realized TDK’s best absorbing characteristics, is used on the walls and ceiling, introducing a new performance realm of the 10m Test Range anechoic chamber with a standard beyond the existing best standard in the world.

Title of the text: Advantages/Site attenuation characteristics

  • ANSI C63.4 Normalized theoretical site attenuation within ±1.3dB was achieved: Realizing next-generation electromagnetic environment even more optimal than the attenuation level of the conventional high-performing 10m Test Range electromagnetic wave anechoic chambers (within ±2.5dB).
  • Achieved levels within CALTS +0.4, -0.8dB, REFTS* ±0.6dB: Complying with antenna calibration test site conditions.
    *REFTS (Reference Test Site): The site attenuation of vertical polarized wave measurement facility. Deviation value required for antenna calibration test site (standard site) is in review at CISPR.
  • Height pattern characteristics: Excellent height pattern characteristics, almost equivalent to theoretical figures and those of an OATS were achieved.
  • Site attenuation uniformity: φ6m (evaluated at 50cm intervals each direction of horizontal and vertical) area variable within ±1.3dB was achieved, realizing a superior field uniformity which measurement environment surpasses the conventional levels.
  • Supports Site VSWR: Compatible with the requirements of the conformance evaluation method (Site VSWR) in CISPR 16-1-4 Ed3.0 and VCCI technical standard 5.3.4 which are required for 1 - 18GHz.
Measurement scenery of "Site VSWR"

Antenna evaluation anechoic chamber (800MHz to 110GHz): Installing the electromagnetic wave absorber IS-030A on the floor between radiation antenna and EUT (equipment under test ) (25 units of 3x3m in this case) can significantly reduce reflected waves from the floor and achieve the Site VSWR standard (SVSWR: 6dB or lower).

Reference Site Method
New test site evaluation method which replaces NSA (Normalized Site Attenuation)
Site evaluation method based on APR (Antenna Pair Reference) / Reference site: Liberty Labs.
Assessment data by "Reference Site Method"
Site performance evaluation using reference dipole antennas
Evaluation through the antenna calibration test site testing method stipulated in CISPR 16-1-5: Using reference dipole antennas which allow theoretical calculation (moment method and such).
Site performance evaluation using reference dipole antennas