| 摘要 |
865,516. Q measurements. COMPAGNIE GENERALE D'ELECTRICITE. Sept. 3, 1959 [Sept. 26, 1958], No. 30083/59. Drawings to Specification. Class 37. In apparatus for measuring the Q of a resonant cavity comprising a generator of high frequency current equal in frequency to that of the resonance of the cavity, a source of saw-tooth waveform and a modulator to which it is applied to frequency modulate the high frequency, a second modulator wherein the frequency modulated waves are amplitude modulated at a lower frequency, means for applying the doubly modulated waves to the resonant cavity, means for detecting its output, and an oscilloscope to which the detected wave is applied the horizontal sweep of which is controlled by the saw-tooth wave in such a way that there appears on its screen a curve showing a principal lobe for the frequency of resonance of the cavity and two secondary symmetrical lobes, the frequency of the voltage supplied by the low frequency generator being adjusted to such a value fm that the frequency interval between the peaks of the secondary lobes is equal to three times the width of the principal lobe at the mid-ordinate of its peak. The value Q is then given by Q = 3fo/2fm. The high frequency is generated in a reflex klystron and is frequency modulated by applying the saw-tooth voltage to one of its electrodes, amplitude modulation being subsequently effected in a ferrite attenuator. |
