Field Gradient Control Of Magnetostatic Waves For Microwave Signal Processing Applications

Although magnetostatic wave devices normally employ spatially uniform magnetic bias, control of important features of the modes is afforded through judicious use of dc field gradients. Such control can be the basis for new forms of microwave signal processors. The authors discuss the manner in which gradients in either the field magnitude, direction or both can be employed to synthesize wave dispersion characteristics or mode spectra. This is done to control prespecified characteristics such as frequency rf energy distribution, impedance, velocity of energy propagation and the threshold governing the onset of nonlinear effects due to parametrically-unstable spin waves. The way in which the normal boundary conditions, controlled by the sample geometry, interact with those imposed by the field gradient is also described.