DocumentCode :
927301
Title :
The Q of a Microwave Cavity by Comparison with a Calibrated High-Frequency Circuit
Author :
Lecaine, Hugh
Author_Institution :
National Research Council of Canada, Ottawa, Canada
Volume :
40
Issue :
2
fYear :
1952
Firstpage :
155
Lastpage :
157
Abstract :
A comparison method has been developed for the direct measurement of cavity Q at microwave frequencies. It is particularly useful for high values of Q, such as 5,000 to 15,000. The over-all error in the measurement is estimated to be less than ±3 per cent. A two-channel superheterodyne technique is used, in which both channels are driven by the same frequency-swept oscillator, and both channels use the same local oscillator. The cavity is inserted in the radio-frequency stage of the first channel, and a comparison circuit is inserted in the intermediate-frequency stage of the parallel channel. The two resonance curves are displayed on the same oscilloscope for alternate sweeps of the oscillator. When the resonance curves are made to coincide, the Q of the cavity is n times the Q of the comparison circuit, where n is the ratio of radio frequency to intermediate frequency. Cavity shunt resistances can be measured on the same apparatus.
Keywords :
Frequency measurement; Local oscillators; Microwave circuits; Microwave frequencies; Microwave measurements; Microwave oscillators; Oscilloscopes; Q measurement; Radio frequency; Resonance;
fLanguage :
English
Journal_Title :
Proceedings of the IRE
Publisher :
ieee
ISSN :
0096-8390
Type :
jour
DOI :
10.1109/JRPROC.1952.274014
Filename :
4050913
Link To Document :
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