An improved finite-element formulation using quadratic shape functions is presented. The improvement in accuracy of the method is investigated in comparative to the case of using linear shape functions. As an example of using the quadratic shape functions, an accurate analysis of a microstrip waveguide has been carried out. Good agreement between the finite-element solutions and the other numerical solutions is confirmed. This agreement shows the validity and usefulness of the method.

The time delay of magnetostatic wave in a YIG slab has been studied experimentally, where the nonuniform dc magnetic field is applied normal to a slab surface by using the artificially sharpened magnetic pole piece. The non-dispersive group delay characteristics are found, and the effect of nonuniform magnetic field on the propagation loss is also investigated.

A variational formula is presented for magnetostatic wave resonators. The formula is applied to the magnetized ferrite disk and ring resonators. The resonant mode charts are shown, and it is found that if the aspect of the resonator is optimized, a single mode resonance can be realized on a wide frequency range.

The filter characteristics of electromagnetic TM waves in a dielectric slab waveguide having a sinusoidal variation of its permittivity in the propagation direction are investigated. With the aid of a singular perturbation procedure, the coupled-mode equations governing the nature of TM waves interactions are deduced for both symmetric and asymmetric first-order Bragg interactions. Omitting the end effects, an expression describing the characteristics of reflection of TM wave is derived from the boundary value problem in the propagation direction. Experiments on reflection characteristics have been performed in the millimeter wave region where the dielectric slab created by arranging an Aflon slab in periodic fashion in a Teflon slab is tested as a permittivity-modulated slab waveguide. Return loss data and observed stopband responses are reasonably consistent with theory.

The degeneracy of TE and TM modes in a transversely magnetized ferrite slab is investigated from the dispersion diagram. The Bragg reflection phenomena in the periodic structures are employed to measure the propagation characteristics of both modes in the vicinity of the degenerate point. A theoretical study of the Bragg reflection phenomena in a surface-corrugated polycrystalline YIG slab is carried out on the basis of an equivalent-circuit model, and then experiments are performed. Existence of the degeneracy of TE and TM modes in the millimeter wave frequencies is confirmed experimentally.