The RE101 test requires the measurment of magnetic emissions using a shielded loop sensor. The sensor has 36 turns with a 13.3 cm diameter enclosed in a shield. It has an insulating base/spacer which permits the placement of the loop at a distance of 7 cm from the device under test.

A BNC connector permits the output of the loop to be connected to an EMI receiver or spectrum analyzer.

The loop is calibrated and is provided with a correction factor showing the values in dB which are added to the spectrum analyzer dB uV reading to obtain the levels of emissions in terms of either dB uV/m or dB PT/uV. The correction factor is shown in the figure below.