EM TEST CWS 500D - Calibration Setup EM TEST and IEC 61000-4-6

EM Test CWS500 D
User manual V 1.07 21 / 34
5.5.2. Calibration Setup EM TEST and IEC 61000-4-6
The setup for calibration according to IEC 61000-4-6 is shown in the figure 5.7. below. EM Test has carefully
tested the calibration setup and propose to eliminate the 150Ω terminating resistor on the AE port for CDN
calibration. ( Fig 5.8)
Fig 5.7 : Calibration Setup per IEC 61000-4-6 Fig 5.8 : Calibration Setup EM Test method
Reason for the EM Test calibration test setup:
- The AE port must only be applied to unshielded cables (shielded cables have their shielding connected to the
ground reference plane of the AE port).
- The uncoupling inductance according to the standard is >280µH. The EM Test CDN has a higher inductance
(CDN M3 typical >500µH). Therefore, the calibration error at 150kHz is max 10% and will be reduced by
increasing the frequency. (Error at 400kHz approx.5%).
- The tolerance of the applied signal according to IEC 61000-4-6 is ± 25%. The figure below shows two CDN M3
10V measurements with different calibration methods. The results are within the ± 25% limit and the result is
very similar.
- The influence of the internal synthesizer attenuator is responsible for the non-linear result of the calibration
test.
EM Test Calibration Setup
EUT port : 1x 150Ω:
R100 ( 100Ω )
power meter ( 50Ω )
AE port : open circuit
IEC 61000-4-6 Setup
EUT port : 1x 150Ω:
R100 ( 100Ω )
power meter ( 50Ω )
AE port : 1x 150Ω:
R100 ( 100Ω )
terminating ( 50Ω )
Fig 5.9 : Difference between the calibration methods
However, for a calibration according to the standard it is necessary to add the additional calibration acessories
for the AE port termination :
150Ω to 100Ω adapter : R-100
50Ω termination resistor :T-50