Current thin film heads without gap-nulls

Two types of reproducing heads without gap-nulls for inductive longitudinal magnetic recording have been modeled theoretically. The first type of head is a superposition of several infinitely long and current-carrying thin-film sheets with the sheet width varying linearly and flush with one side. The second type of head has the form of the continuous distribution of thin films, that is, a current head with trapezoidal cross section. The spectral responses of these heads are compared with that of a conventional Karlquist head. It is concluded that these two types of current heads can reproduce signals at much shorter wavelengths than conventional Karlquist heads and yield no gap-nulls