| 摘要 |
An apparatus for tracking the varying resonant frequency of an electrically resonant structure, characterized by: a variable frequency oscillator providing an excitation signal of a variable frequency encompassing the possible resonant frequency range of the resonant structure, a bidirectional RF transmission line connecting the variable frequency oscillator and the resonant structure, the transmission line incorporating a directional coupler which generates a directional coupler signal proportional to the reflected signal from the resonant structure, the directional coupler signal being conditioned by a processor to provide a feedback signal to the input of the variable frequency oscillator, such that the mean frequency of the excitation signal is caused to continuously track the varying resonant frequency resonant structure. Typically the tracking of the varying resonant frequency involves at least two functions, a first search function for initially searching the possible resonant frequency range of the resonant structure and, once resonance of the resonant structure is established, a second following function for following the variable resonant frequency as it varies as a function of time.
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