Quality factor of microstrip resonators based on YBCO films, in the frequency range 1.5-2 GHz

Higher usage of the mobile phone and internet services has increased the demands on the mobile frequency spectrum resulting in the congestion of the frequency bands used for the wireless communication systems. Consequently the adjacent channel interference and hence the number of dropout calls have increased. High Temperature Superconducting (HTS) microstrip filters enable the decrease in the adjacent channel interference, improvement of the audio quality and increase of the sensitivity of wireless communication receivers. Improvements in the performance of microwave HTS devices directly depend on lowering the surface resistance of the HTS thin films. Therefore it is important to fabricate HTS thin films with the lowest possible surface resistance. In general, microwave losses of HTS films depend on several factors such as the substrate material and deposition technique. In this paper we report results on YBa₂Cu₃O_7-d (YBCO) thin films deposited on Al₂O₃ substrates with CeO₂ sub layer. We have used a microstrip resonator for reflection parameter measurements for data processing. We have carried out the measurements of microstrip meander resonators quality factor at frequency 1.8 GHz. Resonators are prepared by the wet etching technique, from the YBCO films, with sapphire substrate and CeO₂ sub layer, which is obtained by the laser ablation method. In our investigation we have used a single-port measurement method (using reflection factor).