Dependence of reproducing gap null on medium permeability and spacing
H.N. Bertram, D. Lindholm · IEEE Transactions on Magnetics · 1982
Experimental evidence and theoretical calculations show that the position of the reproducing gap null is influenced by the anisotropic permeability of the recording medium and the head-to-medium separation. Results indicate a stronger influence than expected from previous theory. The shift is typically 4 percent for a mean relative permeability of two and minimal head separation.