Specify the frequency for analyzing by select Analysis > Setup. In this case, we use Linear Frequency Sweep. From our project, the cut-off frequency is 4.8 GHz. So, the start frequency should less than the cut-off frequency and the stop frequency should more than cut-off frequency. We set step frequency to 0.1 GHz for more detail. Tick on the Compute Currents box for compute the current density.