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Proceedings Paper

New transmission-cavity technique for surface impedance measurements in the submillimeter-wave region
Author(s): W. Mayr; Alfred Philipp; G. Kallinger
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Paper Abstract

The measurement of the surface impedance of a sample at microwave frequencies is usually done by placing the sample inside a microwave cavity. The resulting change of the quality factor and of the resonance frequency of the cavity can be used to determine the complex surface impedance of the sample. Instead of measuring the whole lorentzian curve a fast method using automatic frequency control (AFC) can be used where only the transmitted signal amplitude and the resonance frequency are measured. This method is very useful whenever the surface impedance depends strongly on temperature as for example in the case of a superconducting transition and when the temperature stabilization of the small cavity is a severe problem. However this method can only be used with a microwave source which exhibits nearly no dependence of the output power on the frequency and which has a very good frequency stabilization. Such sources are available only for frequencies up to 60 GHz. Problems with backward wave oscillators (BWO) at higher frequencies can be avoided by using a new computer controlled frequency (CCF) method. This method offers the advantage of a full control over the output frequency of the source and the ability to measure very fast and with high accuracy all the parameters necessary for the determination of the surface impedance.

Paper Details

Date Published: 13 November 1998
PDF: 10 pages
Proc. SPIE 3465, Millimeter and Submillimeter Waves IV, (13 November 1998); doi: 10.1117/12.331174
Show Author Affiliations
W. Mayr, Univ. Wien (Austria) and Ludwig Boltzmann Institut fur Festkorperphysik (Austria)
Alfred Philipp, Univ. Wien (Austria) and Ludwig Boltzmann Institut fur Festkorperphysik (Austria)
G. Kallinger, Univ. Wien (Austria) and Ludwig Boltzmann Institut fur Festkorperphysik (Austria)

Published in SPIE Proceedings Vol. 3465:
Millimeter and Submillimeter Waves IV
Mohammed N. Afsar, Editor(s)

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