To facilitate high frequency operation, transmission lines for high-speed interconnect applications in CMOS technologies are loaded with patterned permalloy or other ferromagnetic material films. Patterning the permalloy films as a plurality of segments results in control of the domain structures in the permalloy segments such that ferromagnetic resonance (FMR) effects are eliminated and eddy-current effects are reduced, thereby allowing operation of the transmission lines at frequencies of 20 GHz or higher. In addition, the patterned permalloy reduces the magnetic field coupling between two adjacent transmission lines. A novel ferromagnetic thin film characterization method is also employed to measure the microwave permeability of the patterned permalloy films and verify their high frequency operational characteristics.