Magnetostatic wave propagation through periodic metallic gratings

A novel technology for analog, real time, signal processing at GHz frequencies is described utilizing the interaction of slow magnetostatic waves in magnetically biased films of yttrium iron garnet, grown by liquid phase epitaxy on substrates of gadolinium gallium garnet, with periodic structures. The dispersion, attentuation and tunability characteristics of these waves are reviewed together with methods for efficient microstrip transduction, controlled spatial tapping and realizing matched terminations. Comparisons are drawn with surface acoustic wave technology in the context of available parameters and performing nonrecursive transversal filtering. Basic experiments and theoretical results for periodic structures, comprised of metal overlay arrays, both at normal and oblique incidence are described. The paper concludes with a survey of magnetostatic devices for GHz signal processing applications including bandpass filters, resonator-filters, delay lines, oscillators and pulse compression filters.