(a) Sketch of geometry of laminated insulator-ferromagnetic on edge composite adapted to coaxial line geometry. Propagation vector k , and E and H fields corresponding to fundamental mode are also indicated. (b) Micrograph of part of surface of a wound torus that is made by winding 0.4- μ m -thick amorphous cobalt-based alloy deposited by magnetron sputtering on 8- μ m -thick mylar.^[30]