CONNECTION OF S-MATRIX OF WAVE-GUIDE AND PERIODICAL STRUCTURES WITH COMPLEX FREQUENCY-SPECTRUM

A number of relationships are given in this paper which allow to conne ct the values of S-matrices elements of open nodes with a discrete spa tial spectrum (waveguides and gratings) on various sheets of analytic continuation of a frequency parameter, to find zeroes of these element s, etc. According to it, a scheme of reconstructing frequency dependen ces of S-matrices by the known sets of complex eigen frequencies has b een constructed. A number of simple expressions are presented due to w hich one can carry out an effective analysis of the resonance properti es of diffraction characteristics of various modes.