DESIGN OF RF SYSTEMS AT HF AND VHF FOR COMMUNICATIONS, RADAR AND BIOMEDICAL APPLICATIONS: MINIATURIZATION OF RADIATING ELEMENTS AND SYNTHESIS OF TUNING AND MATCHING NETWORKS

Electrically small antennas have received an increasing interest especially for both radar and medical applications. In this dissertation, several approaches for antennas miniaturization have been studied and proposed for Over the Horizon (OTH) phased array radars. In the last case, the need to reduce the size of the antenna is dictated by the wavelengths in the HF frequency range. To this aim, most of this dissertation is focused on a new methodology for reaching both wideband and small sizes characteristics of the antenna for radar purposes. Additionally, several matching networks have been studied in order to reduce the mutual coupling between the radiating elements in the array. As a side work, by exploiting the miniaturization of the antennas, Radio Frequency coils for Magnetic Resonance Imaging application have been analyzed. A new approach has been presented in order to study the behaviour of these antennas in realistic environments.