One example discloses a device for electromagnetic structural characterization, including: a controller having an electromagnetic transmitter output and a communications interface; wherein the controller is configured to send a signal over the electromagnetic transmitter output that causes an electromagnetic transmitter to generate a first electrical field (E1) and a first magnetic field (H1); wherein the controller configured to receive over the communications interface a second electric field (E2) and a second magnetic field (H2) received by an electromagnetic receiver; wherein the first electrical field and the first magnetic field correspond to when the electromagnetic transmitter is at a first location proximate to a structure and the second electrical field and the second magnetic field correspond to when the electromagnetic receiver is at a second location proximate to the structure; and wherein the controller is configured to calculate an impedance based on the electric and magnetic fields interacting with the structure.