Electromagnetic Reverberation Chambers or Mode Stirred Chambers

Test environments for EMC are, e.g., (semi-)anechoic chambers, Crawford or GTEM cells or open waveguides or open area test sites (OATS). A modern option is to use a Electromagnetic Reverberation Chamber (ERC).

Methods for testing the interference immunity of devices are described in [1,], [2], [4], among others.

ERCs represent test environments that are used in electromagnetic compatibility (EMC), especially in the context of interference immunity tests. For this purpose, an asymmetrically shaped, rotatably mounted sheet metal, the so-called mode stirrer or stirrer, is installed in an electromagnetic cavity resonator, which is operated at a frequency above its 60th natural mode, and rotated gradually or continuously. For different stirrer positions, many irregular modes are excited in the resonator or mean values ​​are formed in the continuous process. The system is to be designed in such a way that the electric field strength averaged over all stirrer positions in a part of the resonator for frequencies above a lower limit frequency, which is dependent on the dimensions of the resonator, has the following property: Its magnitude is constant, its direction and polarization are evenly distributed.


[1] Schwab, A. and Kürner, W .: Electromagnetic Compatibility, Springer-Verlag Berlin Heidelberg, 2011, p. 349ff
[2] DIN EN 61000-4-3 (VDE 0847 part 4-3) Immunity to high-frequency electromagnetic fields (test standard)
[3] IEC 61000-4-21 Electromagnetic Compatibility (EMC) Part 4: Testing and measurement techniques, Section 21: Reverberation Chamber Test Modes, Version 08/10/2001
[4] MIL-STD 461 F.
[5] David Pozar, Microwave Engineering, John Wiley & Sons, 3rd edition 2005

The aim of the ongoing research projects is to measure the power taken from the circuit from a known external field. Knowing this value allows the developer to apply specific EMC measures to ensure interference immunity.

To achieve this goal, a mode swirl chamber (MVK) with a high quality is necessary, since only in an MVK the field acting on an introduced circuit cannot be changed by aligning the test object; the high quality ensures that the difference between the power fed in and power out can be measured correctly. Field distribution, the influence of the test object and the statistical evaluation of the measurement results require a great deal of effort.

Goals already achieved:

Design of a cuboid MVK for frequencies above 800 MHz, construction and automated calibration of a MVK based on a cuboid (04/2011)
Construction and automated calibration of an MVK based on a semi-ellipsoid (09/2011)
first measurements with simple test bodies (foam block, copper foil, baby monitor, mobile phone, WLAN card, Bluetooth headset) (09/2011)
Elimination of sources of error (antenna adjustment, mismatching of measuring devices) (01/2012)
Statistical series measurements on test objects (01/2013)

In the next step, a correlation with the results of a standard-compliant immunity test is planned. For the required precise simulation of the fields within the MVK, taking into account the influence of the examinee, we are currently working together with the professorships for mathematics (Prof. Bause, Faculty of Mechanical Engineering) and computer-aided statistics (Prof. Knoth, Faculty of Economics and Social Sciences) the HSU and the University of Mainz (Prof. Lukocova) prepared an application for funding from the German Research Foundation.

Contact: Lars Ole Fichte


Letzte Änderung: 28. Juni 2021