学术报告 报告题目：Microwave whispering gallery resonators 报告人： Dr. Sergey A. Bunyaev

报告题目：Microwave whispering gallery resonators

报告人：  Dr. Sergey A. Bunyaev

主持人：  Prof. Andrey Andrenko

时  间：  2016年5月18日（星期三）10:00-11:00

地  点：  广东顺德最热门的网赌网址大全卡内基梅隆大学国际联合研究院学术报告厅M101

Abstract: Whispering gallery mode dielectric resonators (WGR’s) are of a great importance for applications from microwave to optic range because they have highest Q-factors. At microwaves they are used in high selective filters, low phase-noise oscillators and as sensors for materials characterization.

Special focus will be given to the advantages of developed WGR based technique for impedance measurements of high-temperature superconductors (HTS). Surface impedance Zs=Rs+iXs is the most informative characteristic which is important for understanding of the mechanism of high temperature superconductivity. For high sensitive measurements of Zs it is crucial to exclude normal metal elements from resonator structure and to use dielectric resonators made of materials with small value of loss tangent. Results of comprehensive study and comparison of some types of microwave WGR’s designed for HTS impedance characterization will be presented. The resonators are made of single crystal sapphire in the shapes of cylindrical disc, radially-slotted disc, truncated cone and hemisphere. The features of resonance frequency spectra, electromagnetic field distribution and interaction between microwave field and a sample under test will be considered.

Additionally properties of a proposed Ka-band microstrip WGR will be discussed. This resonator demonstrates Q-factor up to 890, is suitable for integration into a microstrip or planar circuits, and can be used in different microwave applications.

Introduction on the lecturer: After obtaining Bachelor in 2001 and Master in 2002 degrees (both with honour) in Electronics from Kharkiv National University of Radio Electronics, Sergey Bunyaev started his career at Institute of Radiophysics and Electronics, National Academy of Science of Ukraine (IRE-NASU) as Engineer. In 2006 he became a PhD student (PhD degree was awarded in 2009), in 2009 was promoted to Research Scientist. During his work at IRE-NASU S.A. Bunyaev worked on design, numerical simulation and experimental characterization of new types of whispering gallery mode dielectric cavities with superconducting screens. He also contributed to the design and fabrication of several experimental setups for microwave cryogenic laboratory. In 2010 Dr. Bunyaev joined IFIMUP and IN, Departamento de Fisica, Universidade do Porto, as Postdoctoral researcher with a competitive FCT grant. His main research topic here is dynamic magnetization of structured magnetic nanoelements. He participated in 13 national and international research projects both in Ukraine, Germany and Portugal. In 2007-2009 he was a Principal Investigator of a competitive research project funded by NASU. In 2008 he received the IEEE Antennas and Propagation Society Graduate Research Award for the project “Twin Modes' as a Hidden Effect of Anisotropic Dielectric Hemisphere”.

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