Anomalous rejection in the slot resonators on the higher-mode oscillations

The efficiency of exciting the slotted cavities of a diffraction grating microwave oscillators is determined as function of depth L and slot width πθ. The anomalous behavior of antiresonant minima of excitation for a π-mode oscillations to the point of their intersection with resonant maxima and their suppression is revealed. When electron slow is in synchronism higher order space harmonics of the field the anomalous rejection occurs at several values of θ. The deviation from the non-optimal values of θ made it possible to ensure that a wavelength λ of generated oscillations was shortened by a factor of 15 (against the known values) due to use of Wood´s anomaly regime.