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Influence of strength and asymmetry of the coupling between a cavity and a transmission line on measurement of complex permittivity
Author(s) -
Ikeda Masaaki,
Nishida Kazuaki,
Nagata Yasuyuki,
Shimasaki Hitoshi,
Akiyama Masahiro
Publication year - 2010
Publication title -
microwave and optical technology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 76
eISSN - 1098-2760
pISSN - 0895-2477
DOI - 10.1002/mop.24988
Subject(s) - permittivity , asymmetry , microwave , transmission line , coupling (piping) , relative permittivity , coupling strength , lossy compression , physics , condensed matter physics , materials science , computational physics , electronic engineering , optoelectronics , electrical engineering , mathematics , engineering , quantum mechanics , dielectric , composite material , statistics
Influence of the strength and the asymmetry of input‐output ports on the measurement of complex permittivity by the resonant cavity perturbation method was investigated experimentally.We adopted the | S 21 | as the criterion of the strength, and the difference between S 11 and S 22 as the criterion of the asymmetry. When the coupling is symmetric, the real part of permittivity can be evaluated in strong coupling state up to −3 dB of coupling. The imaginary part of permittivity can be evaluated up to −14 dB of coupling. Imaginary part of the relative permittivity ε″ r was calculated using the conventional equation, which is based on the complete symmetry of the coupling of input‐output ports. For the measurement of high‐Q materials, calculated ε″ r is strongly affected by the asymmetry in the strongly coupled region. For the measurement of lossy materials, the inevitable asymmetry and the strong coupling allow enough exact evaluation of ε″ r . © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 706–709, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24988