Group delay characteristics of magnetostatic forward volume waves in a nonuniformly magnetized YIG film

Group delay characteristics of magnetostatic forward volume wave in a nonuniformly magnetized YIG film are investigated. Large loss reduction of waves is experimentally demonstrated with long time delay more than 3 µ second at S band frequency. Phenomenological theory for the propagation loss factor in the non-uniform bias field is given under numerical estimation of ray path equations. As the result mechanism of loss reduction can be explained as the lens effect of magnetostatic forward volume wave beams.