2000 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.

IEEE Microwave and Guided Wave Letters
Volume 10 Number 9, September 2000

Table of Contents for this issue

Complete paper in PDF format

Resonance Degeneration and Spurious Mode Suppression in a Cryogenic Whispering Gallery Mode Sapphire Resonator

O. Di Monaco, Y. Kersale' and V. Giordano

Page 368.

Abstract:

A method to solve the main resonance degeneration and the spurious mode problem for a cryogenic Whispering Gallery Mode Sapphire Resonator (WGMSR) is reported. Two thin metal wires are deposited on top of the sapphire disk. With an appropriate choice of the relative radial direction and the orientation of these wires with respect to the coupling probe, a dominant perturbation for one of two excited resonance modes has been realized. Moreover, the spurious modes around the selected resonance mode are being suppressed in a frequency span of the order of 300 MHz, without modification of the main resonance performance.

In this letter, the efficiency of this method is demonstrated experimentally for a cryogenic WGMSR realized with a very high purity sapphire monocrystal operating near 7 GHz.

References

  1. D. G. Santiago and G. J. Dick, "Microwave frequency discriminator with a cooled sapphire resonator for ultra-low phase noise", in IEEE Frequency Control Symp., 1992.
  2. J. H. Searls, S. Edwards, E. N. Ivanov, M. E. Tobar and R. Woode, "High-Q T.E. stabilized sapphire microwave resonators and low noise oscillators", in Proc. 8th EFTF, Munich, Germany,March 9-11 1994, pp.  134-146. 
  3. M. E. Tobar, "Effects of spurious modes in cavity resonators", J. Phys. D: Appl. Phys., vol. 26, pp.  2022-2027, 1993.
  4. R. A. Woode, M. E. Tobar, E. N. Ivanov and D. G. Blair, "An ultra-low noise microwave oscillator based on a high-Q liquid nitrogen cooled sapphire resonator", IEEE Trans. Ultrason.,Ferroelect., Freq. Contr., vol. 43, no. 5, pp.  936-941, 1996.
  5. O. Di Monaco, "Resonateurs saphir microondes cryogeniques à très grand coefficient de surtension pour applications métrologiques", Thèse de Doctorat, Univ. of Franche-Comte', Besancon, France, July 1997 .
  6. D. G. Santiago, G. J. Dick and A. Prata, "Mode control of cryogenic whispering gallery mode sapphire dielectric-ring resonators", IEEE Trans. Microwave Theory Tech., vol. 42, pp.  52-55, Jan.  1994.
  7. Y. Kobayashi and T. Senju, "Resonant modes in shielded uniaxial-anisotropic dielectric rod resonators", IEEE Microwave Theory Tech., vol. 41, pp.  2198-2205,  Dec.  1993.
  8. O. Di Monaco, W. Daniau, I. Lajoie, Y. Gruson, M. Chaubet and V. Giordano, "Mode selection for a whispering gallery mode resonator", IEE Electron. Lett., vol. 32, no.  7, 1996.
  9. S. Nogi, K. Fukui, M. Kojima and S. Tanaka, "Effective methods for suppression of undesired cavity modes using microwave absorbers", Electron. Commun. Jpn., vol. 74, no. 9, 1991.
  10. M. E. Tobar, A. J. Giles, S. Edwards and J. Searls, "High-Q thermo-electric stabilized sapphire microwave resonators for low noise applications", IEEE Trans. Ultrason.,Ferroelect., Freq. Contr., vol. 45, pp.  391-396, May  1994.