Precise measurements of surface resistance of high temperature superconducting thin films using a novel method of Q-factor computations for sapphire dielectric resonators in the transmission mode

Leong, Kenneth Tak Ming (2000) Precise measurements of surface resistance of high temperature superconducting thin films using a novel method of Q-factor computations for sapphire dielectric resonators in the transmission mode. PhD thesis, James Cook University.

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Abstract

The work presented in this thesis belongs to the area of microwave characterisation of High Temperature Superconductor (HTS) materials and is devoted to precise measurements of the surface resistance Rₛ of HTS thin films using the sapphire dielectric resonator structure. Accurate measurements of surface resistance of IITS films are essential for advancement of knowledge and technological progress in the field especially for commercial applications of HTS materials in wireless communications.

In typical measurements of Rₛ, the superconductor film sample is made an integral part of a microwave resonator, which is a structure that can store microwave energy. The unloaded quality factor Q₀ of the structure measured typically in the transmission mode and is used for calculations of the surface resistance. While there is a need for accurate procedures to measure the surface resistance, no standard procedure has yet been developed for such purpose as no detailed comparative studies were done on the accuracy of existing techniques as well as a lack of superior techniques to determine the unloaded Q₀ -factor of microwave resonators working in the transmission mode.

In this thesis, a novel method to accurately and conveniently determine the unloaded Q₀-factor of the transmission mode sapphire resonator for measurements of Rₛ of high temperature superconducting thin films is presented. The developed Transmission Mode Q₀-Factor Technique is based on measurements of S-parameters and it accounts for practical effects introduced by a real measurement system which are not always accounted for in simple Q₀-factor techniques. The developed method is applicable not only to the testing of HTS materials using sapphire resonators, but can be successfully employed in any measurements involving transmission mode dielectric resonators.

Item ID: 41458
Item Type: Thesis (PhD)
Keywords: dielectric resonators; electronics; high temperature superconductors; HTS; material characterisation; material characterization; microwave electronics; oscillators; sapphire; surface resistance; thin films; transmission mode
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Publications arising from this thesis are available from the Related URLs field. The publications are:

Leong, Kenneth, Mazierska, Janina, and Krupka, Jerzy (1997) Measurements of unloaded Q-factor of transmission mode dielectric resonators. In: 1997 IEEE MTT-S International Microwave Symposium Digest (3), pp. 1639-1642. From: 1997 IEEE MTT-S International Microwave Symposium, 8-13 June 1997, Denver, Colorado, USA.

J. Ceremuga, J. Wosik, R. Grabovickic, K. Leong, H. Kinder, M. Konczykowski, ''Power effects in co-evaporated YBCO thin films", Proceedings of the Fourth Symposium on High Temperature Superconductors in High Frequency Fields, Monterey, 29 September- 2 October 1996.

Leong, K., and Mazierska, J. (1998) Accounting for lossy coupling in measurements of Q-factors of transmission mode dielectric resonators. In: Proceedings of the 1998 Asia-Pacific Microwave Conference, APMC 98, pp. 209-212. From: APMC 1998: Beyond the Wireless Multimedia Society, 8-11 December 1998, Yokohama, Japan.

Ceremuga, J., Leong, K., and Grabovickic, R. (1996) Characterisation of high temperature superconducting films using a sapphire resonator and fitting procedures for calculations of the Q-Factor. In: Proceedings of the 11th International Microwave Conference MIKON 96. From: 11th International Microwave Conference, 27-30 May 1996, Warsaw, Poland.

Date Deposited: 26 Nov 2015 04:22
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