Graduate School of Science and Engineering, Yamagata University, Japan

Biography: AAtsushi Saito received the B.E., M.E., and D.E. degrees in Department of Electrical Engineering from Nagaoka University of Technology (NUT), Japan, in 1994, 1996, and 1999, respectively. During 1999-2001, he was a research associate in NUT. From 2001 to 2003, he was a research fellow in KARC-CRL. He is now associate professor in Graduate School of Science and Engineering, Yamagata University. His current research interests are superconducting devices.
He has published over 130 journal papers with peer-review process. He received a paper award 2015 of the JSAP Superconductor Division and CST university publication award 2015.

Speech Title: 100-W-class transmit filter using thick-disk resonator made by GdBCO superconducting bulk
Abstract: High-temperature superconducting (HTS) filters can efficiently use frequency resources because they have low insertion loss and sharp skirt characteristics. For mobile communication systems, receive HTS filters have been used in the United States and in China. However, transmit HTS filters have not been commercially used because they need to have high power-handling capability. We have reported that GdBa2Cu3Oy (GdBCO) superconducting bulks fabricated by using a modified quench and melt growth (QMG) method [M. Morita, M. Kumada, A. Sato, H. Teshima, and H. Hirano, Physica C, Vol. 463-465, pp. 387-393, 2007.] have a surface resistance (Rs), that is enough low for use as microwave filters. [A. Saito, N. Sekiya, H. Teshima, H. Obara, Y. Noguchi, H. Hirano, S. Hirano, and S. Ohshima, Physica C, Vol. 445-448, pp. 330-333, 2006.] Using this availability, we have proposed and developed transmit band-pass filters (BPFs) using HTS bulk resonators. [A. Saito, R. Tsurui, T. Kato, K. Nakajima, H. Teshima, and S. Ohshima, Appl. Phys. Express, Vol. 8, 043101, 2015.]
In this paper, we present that the development of 100-W-class superconducting BPF with a center frequency of around 5 GHz and a bandwidth of 100 MHz fabricated using thick disk resonators made with GdBCO single-crystal bulk. Additionally, we present some recent works; design of 4-pole cascaded-quadruplet (CQ) BPF and analyzed the frequency responses, design and evaluation of the 5-pole BPF attached with the trimming mechanism for the external quality factor in the conference.
Keywords:band-pass filter, Gd-Ba-Cu-O, HTS, power-handling capability, single-crystal bulk, transmit filter