Electromagnetic near-field measurement is commonly used to characterise radiated emissions of electronic devices and to study interferences between components and systems. To reduce the number of measurements that usually take a long time, the authors apply a post-processing technique based on the plane wave spectrum (PWS) theory. This post-processing enables the computation of the magnetic field at various distances above the device from two planar measurements only. The authors first present the theory of the PWS approach and in a second step, it is applied to a passive circuit to validate the process. Finally, post-processing is applied to an active circuit.