Relations between coercivity and recording performances for Ba-ferrite particulate perpendicular media

Recording performances for Ba-ferrite particulate perpendicular magnetic tapes, with different coercivity values,
H_{c\perp}
=470- 1930 Oe, and other properties substantially unchanged, were investigated with ring-shaped heads. Noise was found to be independent of
H_{c\perp}
. It was ascertained that reproduced voltages and signal-to-noise ratios were constant and highest for
H_{c\perp} > H_{co\perp}, H_{co\perp}
being 600 - 700 Oe depending on recorded wavelength, and that they decreased in proportion to
H_{c\perp}
for
H_{c\perp} < H_{co\perp}
. Therefore, Ba-ferrite tapes can be designed, with their highest performances, to adjust their coercivity so as to meet ferrite or metal head recording ability.