This artificial network is dimensioned according to the specifications in MIL461E or MIL-461F (Measurement of Electromagnetic Interference Characteristics).
It therefore also corresponds to older versions of CISPR 16-1-2 Section 4.2 for a single cell with 50 μH + 5 Ohm || 50 ohms. In contrast to the newer CISPR versions, however, the MIL standard does not place any requirements on the phase of the impedance and on the decoupling between the supply and DUT terminals.