ANNEX IX METHOD(S) OF TESTING FOR IMMUNITY OF ELECTRICAL/ELECTRONIC SUB-ASSEMBLIES TO ELECTROMAGNETIC RADIATION

9. TEM cell testing
9.1. Test method
The TEM (transverse electromagnetic mode) cell generates homogeneous fields between the internal conductor (septum) and housing (ground plane). It is used for testing ESAs (see Figure 1 of Appendix 3 to this Annex)).
9.2. Field strength measurement in a TEM cell
9.2.1. The electric field in the TEM cell shall be determined by using the equation:
E = P × Zd

E
Electric field (volts/metre)

P
Power flowing into cell (W)

Z
Impedance of cell (50 Ω)

d
Separation distance (metres) between the upper wall and the plate (septum).
9.2.2. Alternatively an appropriate field strength sensor shall be placed in the upper half of the TEM cell. In this part of the TEM cell the electronic control unit(s) has only a small influence on the test field. The output of this sensor shall determine the field strength.
9.3. Dimensions of TEM cell
In order to maintain a homogeneous field in the TEM cell and to obtain repeatable measurement results, the test object shall not be larger than one-third of the cell inside height. Recommended TEM cell dimensions are given in Appendix 3, Figures 2 and 3 to this Annex.
9.4. Power, signal and control wires
The TEM cell shall be attached to a co-axial socket panel and connected as closely as possible to a plug connector with an adequate number of pins. The supply and signal leads from the plug connector in the cell wall shall be directly connected to the test object.
The external components such as sensors, power supply and control elements can be connected:
(a) to a screened peripheral;
(b) to a vehicle next to the TEM cell;
or
(c) directly to the screened patchboard.
Screened cables must be used in connecting the TEM cell to the peripheral or the vehicle if the vehicle or peripheral is not in the same or adjacent screened room.
Substituted by Commission Directive 2000/2/EC of 14 January 2000 adapting to technical progress Council Directive 75/322/EEC relating to the suppression of radio interference produced by spark-ignition engines fitted to wheeled agricultural or forestry tractors and Council Directive 74/150/EEC relating to the type-approval of wheeled agricultural or forestry tractors (Text with EEA relevance).