Abstract
Impedance measurements as a function of the applied magnetic field are performed at high frequency using an experimental set-up specially adapted for planar samples, which is based on a microstrip transmission line. Microwave measurement techniques and a consistent data reduction procedure allow obtaining very detailed and accurate impedance measurements. The results for two different samples, an amorphous ribbon and a trilayer thin film, reveal the importance of the ferromagnetic resonance contribution at high frequency. Besides, fine details of the magneto-impedance behavior at low field confirm that it is mainly governed by magnetization processes. At high frequency, when the ferromagnetic resonance contribution at low field weakens, an impedance peak re-appears, that seems to be related with the usual peak that exists at low frequency.
