ISSN:
1089-7623
Source:
AIP Digital Archive
Topics:
Physics
,
Electrical Engineering, Measurement and Control Technology
Notes:
We describe in detail a method that permits determination to an accuracy of 5% or better of the absolute amplitude of a microwave electric field inside a resonant cavity. The method is based on an analysis of the frequency dependence of sampled-power measurements that record the response not only of the cavity but also of the waveguide circuit to which it is connected. Even small reflections from real, nonideal waveguide components lead to a frequency-dependent interference pattern that extends over a much wider range in frequency than does the sharp, resonant response of the cavity. The microwave cavity is modeled with an equivalent circuit model, and the interference pattern in the waveguide circuit is modeled in much the same way as is a Fabry–Pérot interferometer. From this one may obtain accurate values for the Q factor of the cavity resonance and the coupling factor that quantifies how well the cavity is matched to the rest of the waveguide circuit. We also discuss a method to determine accurately the power absorbed by the cavity, using the same waveguide circuit. We confirm the accuracy of the method by comparing to a microwave field-amplitude-dependent physical process, which can be calculated from first principles.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1142303
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