Magnetic field components as a function of height for a simulation driven with a single harmonic frequency. The solid lines and dotted lines represent b_x and b_z, respectively. The top panel shows the kink mode along the loop axis. The middle panel shows the kink mode inside the inhomogeneous layer. The bottom panel shows the Alfvén mode in the inhomogeneous layer. (Note that b_z has nodes at the (x,y) locations in the top and bottom panels.)