The main aim of this work is to analyse the stent response using microwave-based spectrometry (MWS). We have also developed a model (phantom) that simulates the conditions of in vivo experimentation in order to begin with the preparations of a porcine experiment. First of all, we have characterized the probe response using MWS to the presence of a stent (19 mm length, 3.5 mm diameter) in open-air conditions, defining its natural phenomena: resonance and notch (antiresonance or local minimum). We have determined the maximum distance between probe and stent allowing both: the notch detection and the maximum tolerated misalignment. In this way, we have performed a complete study of the appearance of the notch recently discovered. As a matter of fact the appearance of the notch has been associated to the studied stent, and to its relative position to the probe. Secondly, we have developed new phantoms with the aim to simulate the electric properties of a biologic body, based on different criteria such as rigidity, permittivity and invariability of electric properties over time. We have measured, at different distances, the stent response obtained with MWS. This is fully related to the electrical properties of the developed phantom. Furthermore, we have been able to correlate the notch phenomenon to the electrical properties of the environment in which the stent is found.