[IEEE Proceedings of III International Seminar/Workshop on Direct and Inverse Problems of Electromagnetic and Acoustic Wave Theory. DIPED-98 - Tbilisi, Georgia (1998.11.5-1998.11.5)] Proceedings of III International Seminar/Workshop on Direct and Inverse Problems of Electromagnetic and Acoustic Wave Theory. (IEEE Cat. No.98EX163) - Numerical investigation of resonance diffraction characteristics of cascaded gratings (TM-case)