Modeling for RF noise suppressor using a magnetic film on coplanar transmission line

A finite-element method is applied to analyze the electromagnetic field and loss generation of a soft magnetic thin film on a coplanar transmission line for which the dimension of the magnetic film is designed to control the center frequency and bandwidth of the radio-frequency (RF) electromagnetic noise attenuation in the gigahertz range without external applied magnetic fields. The coplanar transmission line with characteristic impedance of 50 Ω has total width, width of signal line, and thickness of 400, 50, and 3 μm, respectively. The change of the magnetic field distribution, the induced surface current density on the coplanar transmission line, and hence the RF noise suppression by soft magnetic films are significant as a function of the width (50-2000 μm) and thickness (0.1, 0.3, 0.5, and 1 μm) of the magnetic film.