MSFVW SCATTERING BY A GRATING OF METAL FINGERS.

Experimental results are reported for the magnetostatic forward volume wave (MSFVW) scattering properties of a grating of metal fingers placed at a variable height above a YIG film. These results are compared with theoretical data obtained using the Weiner-Hopf technique. The theory takes into account mode conversion to higher-order MSFVW modes that results at the discontinuities constituted by the edges of the metal fingers. The theoretical model used ignores the conductivity of the metal fingers because of the attendant complexity of the problem. The experimental results are in excellent agreement with theory and demonstrate that, in the present work where the grating is comprised of only 10 metal fingers with an aggregate length of less than 1 mm, mode conversion is a significantly more important loss mechanism than the ohmic loss due to the conductivity of metal fingers. It is concluded that the conductivity and mode conversion losses do not limit the usefulness of metal-finger reflectors since they may be simultaneously mitigated by lifting the grating above the YIG film.