The field structure of open resonant system with multifocal mirror

The obtaining of sufficient interaction length in diffraction radiation oscillators (DRO), that are working on THz-frequencies, is the actual problem of diffraction electronics. The one of the ways to resolve this problem is the use of composed focused mirror in the open resonant system (ORS). The work goal is the experimental investigations of the resonant modes properties in ORS with focused mirror, composed from several cylindrical reflectors, having the same radius of curvature. For H-polarization of modes it is obtained the field distributions and Q-factor on frequencies 25–38 GHz, if focused mirror was composed from 2, 3 and 4 cylindrical reflectors. The use of the focused mirror, composed form 2 reflectors, is more attractive for DRO worked on TEM00q-resonant mode. When focused mirror is composed from 2, 3 and 4 cylindrical reflectors, the best properties are obtained for TEM(n−1)0q-modes, that having the null of resonant field near the attachment of reflectors.