REPRODUCTION OF MAGNETICALLY RECORDED SIGNALS 



1163 



Below the recording medium, that is for Zq < —6/ 2, 



H. = -lirlrr, sin (27rVX)^'"'"°^'[e"'' - e"'*^'] 



zo < - 8/2 



(13) 



SEMI- INFINITE BLOCK 

 OF PERMEABILITY /I 



d ^RECORDING MEDIUM 

 I / 



(14) 



Fig. 11 — Flat tape under idealized reproducing head. 

 Inside the recording medium, 

 H, = - (4x /^/X) sin (2t^/X) 



r r ^-2x(«o-.)/x ^^ _^ f"" ^+2,(.o-.)/x ^1 



L**-«/2 Jzo J 



H, = - {ArljX) cos (27raK,/X) 



which integrate to 



Zr, = - 27r/^ sin (2irXo/\)l2 - ^-'^/^(g-^-o/x _^ ^2«o/x>^j 



H, = 2irlm cos (2xVX)e"''''(e-''^»'' - e'^''"") 

 8/2 > zo > -5/2 



The Fields in and Under the Reproducing Head 



The idealized reproducing head amounts simply to a semi-infinite block 

 of high permeability material with a flat face spaced a distance d above the 

 surface of the recording medium as shown in Fig. 11. 



(15) 



