Diffraction of magnetostatic surface waves

This paper reports theoretical computations of magneto-static-surface-wave (MSSW) diffraction resulting from the finite length of practical transducers and the pronounced anisotropy of MSSW propagation. The computed MSSW beam spreading is in good agreement with recently reported experimental results. While the MSSW's are found to suffer a significantly larger beam spreading than SAW's on YZ LINb0 sub 3, the total diffraction loss in a typical configuration comprised of two transducers on a YIG film spaced by a distance of 1cm, with both transducers having an overlapping aperture of 5mm, is at most in the order of a few dB. The diffraction loss is found to decrease with increasing frequency. The latter feature is consistent with the MSSW dispersion characteristics, viz, the MSSW wavelength decreases monotonically with increasing frequency. Thus, as the frequency is increased, a radiating MSSW transducer of given physical length becomes electrically longer so that MSSW collimation is improved and the diffraction loss is reduced.