The HFI 02 RF current transformer is designed for the RF measurement of signal lines. Therefore a small metal bracket (associated equipment) is fixed inside the device under test (ground). The RF current transformer is fastened to the small metal bracket and the current to be measured is led through the transformer via a copper wire. The transformer couples a voltage to its 50 ohm SMB output. Common mode currents and sheath currents are attenuated in the transformer shaft.