Hello. I'm using CT (Current Transformer) to measure the current flowing on the power line. The frequency of the current is 13.56 MHz. CT appeared to be metal-shielded (This metal case of CT may be grounded when CT is used). CT has a toroidal shape and the power line under the measurement passes through the center hole of the CT, so azimuthal magnetic field around the power line induces EMF (ElectroMotive Force) on the coil inside the CT. This EMF is measured so the current on the power line is measured. This is the basic story of how CT works. If the current frequency is low like 10 Hz, then I fully accept that CT really works. But I'm now confused at a high-frequency operation. The current is the source of the magnetic field and when the current oscillates, there is not only the magnetic field but also the electric field. The combined field is what we call an EM (ElectroMagnetic) wave. My frequency is 13.56 MHz which is a rather high-frequency, so the power line should play as an EM wave emitting antenna. EM wave generated from the power line propagates to CT first. However, CT has a rather thick metal case (much thicker than the skin depth at this frequency) so EM wave will be reflected from it. It means the magnetic field as a part of the EM wave fails to reach inside the CT so CT should not work! I think the only way for CT to work is that the magnetic field alone pass through the metal so they get in touch with the coil. But..Is it really possible? The time-varying magnetic field can exist alone without the electric field? Of course, a commercial CT works well even for higher frequency. Could you please give me some idea of breaking this confusion?