Ferrite Directional Couplers with Off-Center Apertures (Correspondence)

A recent study of Bethe's small-hole coupling theory has led to an extension of his work to include the case where the coupling aperture is filled with an anisotropic ferrite. This new theory is applicable to any situation where Bethe's coupling theory is useful and is hindered chiefly by inadequate expressions for the magnetic dipole moments of the ferrite.