Radio Frequency Engineering

Absorber Lined Shielding Enclosure (ALSE) Measurements

ALSE validation in the frequency range 150 kHz to 1 GHz is done in accordance to CISPR 25 Ed. 4.0 (2016) on the customer's test bench.


The following two methods are described in the Annex J of the standard: the reference measurement method or the modelled long wire antenna and can be chosen alternatively:

  • Reference measurement method
    In the frequency range from 150 kHz to 30 MHz measurements are done with two monopole antennas. The transmit monopole is placed in one single position of the testbench.
    In the frequency range 30 MHz to 1 GHz the field is generated by a small conical dipole antenna and placed in one position. Measurements are done with biconical, log. per. antennas in horizontal and vertical polarisation. 
    The reference calibrations with the same antenna system were done on our OATS.
  • Modelled long wire antenna method
    The field is transmitted in the frequency range from 150 kHz to 1 GHz with the modelled long wire antenna. As receive antenna an active monopole antenna in vertical polarisation is used up to 30 MHz and biconical and log. per. antennas in horizontal and vertical polarisation are used above 30 MHz.
    The numerical reference data are based on a computer simulation, and are listed in the standard.

In the frequency range 1 GHz to 3 GHz no standard procedure is available and we are using our following procedure: "An Accurate Validation Procedure for Component Testing Chambers". It was published at the CE-Mag issue 11/12 2002 and can be found in our download section.

The field is generated by small omni directional dipole POD16, operated close above the metal plane and placed at the intended EUT position. Measurements are done with a horn antenna in horizontal and vertical polarization.

The use of our calibrated equipment is included for all validations. Customer needs to provide the test bench with proper bonding to the shielding.


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