Design Theory for Magnetostatic Wave Filters and Delay Lines / Theory of One-Port Magnetostatic Wave Resonators

The present paper reports a new unified approach to the design of tunable magnetostatic wave (MSW) filters, delay lines and one-port resonators. This approach is based on the electrodynamic theory of the excitation of surface and volume magnetostatic waves (MSWs) in ferrite films by transducers of an arbitrary type (coplanar, slotline, microstrip etc., including multi-element gratings). An interaction of MSWs with the transducers´ magnetic fields that produce them is taken into account. The theory discribes the generation of the magnetostatic modes due to the finite width of ferrite films and the interaction between these modes. Arbitrary loadings and length of transducers are considered. The analysis is carried both in the magnetostatic and electrodynamic approximation for MSW modes and may be extended on the general case of the spin wave excitation, with the exchange interaction and the surface anisotropy of films being taken into account. Simple analytical expressions derived for response functions of MSW filters, delay lines and resonators provide the base for the modeling and the design of these devices.