Passband filtering of magnetostatic volume waves in two-port planar garnet devices

A novel approach to the magnetostatic volume wave filtering in two-port devices is presented. Instead of acting on the insertion loss of the system by multifinger or reflecting transducer structures, the shaping of the passband is here achieved by modifying the propagation loss through the selective absorption peculiar to multi-layered Ca-doped garnet films. In particular, it is shown that by suitably choosing the characteristic parameters of the material, narrow band filters (- 3 dB bandwidth of 15-40 MHz) operating up to 16 GHz can be worked out. The possible utilization in connection with interdigital transducers is expected to enhance the feasibility of this technique.