The SX-B 3-1 is a passive near-field probe. It detects magnetic field lines emitted orthogonally from the device. Magnetic field lines entering the probe laterally are not detected. In contrast to the SX-R 3-1 H-field probe, the coil of the SX-B 3-1 probe is positioned at a 90° angle. The near-field probe is small and handy. It has a current attenuating sheath and its upper side is electrically shielded. It can be connected to a spectrum analyzer or an oscilloscope with a 50 Ω input.