Atec Frankonia-RIS-3000 - Manual (Page 4)

Homogeneous Field / Uniform Field
To assure the reproducibility of the immunity test, the standard prescribes the homogeneity
of the field generated. The immunity test system incl. anechoic chamber must guarantee a
homogeneous field within a size of 1.5 m x 1.5 m in a distance of 1 m to 3 m from the
transmitting antenna, (e.g. Frankonia type AXL-80). If a smaller surface is sufficient for
exposing the EUT and its connection cables to radiation, the homogeneous field can be
reduced to 0.5 m x 0.5 m. The lowest part of the homogeneous field surface is situated at 0.8 m
above the floor. The level to be set is the max. intended test level incl. modulation. That
means for 10 V/m incl. 80 % AM a level of 18 V/m must be provided. To assure the
correct display of the field probe the measurements are performed without modulation in
the empty anechoic chamber. The homogeneous field has to be established in 1 % steps,
starting from 80 MHz up to 6 GHz. The field homogeneity for the respective frequency is
met, if the difference between the highest and lowest field strength value lies in between
0 dB and +6 dB (12 of 16 measuring points within a field size of 1.5 m x 1.5 m or 4 of 4
measuring points within a field size of 0.5 m x 0.5 m). The high requirements
regarding field homogeneity cannot be met by normal RF-shielded cabins
(without absorber lining). The software uses these data to check the 2 dB saturation of
the system as required by the standard.
Position of the field probe
(equal distances)
0.5m
0.5m
1.5m
1.5m
0.8m
Uniform area
Ground
Calculate Reference File
According to the standard the reference data of desired test field strength shall be calculated from data measured in the field homogeneity
measurement. This can simply be done by use of this function with our control software CR-LAB.
Individual Reference Measurement
Reference data can be determined with two different methods: (from data of homogeneous field) and
. The software supports individual measurement of reference files. This might be necessary if a
defined test level at a defined EUT-position or a profile of test level versus frequency is requested.
Testing
The test setup is described in diagram no. 1 and no. 2. On basis of the reference data (reference calculation or reference measurement)
determined for the respective test setup, the required test level and/or test field strength is adjusted reproducibly in the test run by
means of the control software for each frequency step. For this purpose, the signal is amplitude-modulated with a sine wave of
1 kHz / 80%. The verification of the EUT´s function is performed manually (optically) or, if possible, automatically. In the latter case
the EUT´s function is tested by means of max. four measuring values with respect to its compliance with preset tolerance values. The
determined data, the results, a description of the test system as well as a comment regarding the measurement are summarized by the
software in a measuring record. The data can be printed as well as exported into other data processing programs, e. g. Microsoft
® Word or
Microsoft ® Excel.
Function and operation of the test system
Immunity Test System RIS 3000 / RIS 6000
acc. to IEC/EN 61000-4-3
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