High Frequency Recording With Shielded Planar Type Heads

The response of shielded planar type heads was modelled for coil driving current frequencies up to 5 GHz. The resulting head field distributions were used to write single bits and tracks on graded recording media. The head field distributions over many cycles of the coil driving current were similar and reproducible for frequencies up to 2 GHz. At higher frequencies the head field distributions varied from cycle to cycle and the maximum head field began to drop. Similarly, the signal to noise ratio (SNR) of written tracks was constant up to a write frequency of 2 GHz. At 3 GHz the SNR dropped by 3 dB and at 5 GHz performance was very poor. The effect of head field rise time was also examined and it was found that reducing the head field rise time may improve the SNR of written tracks in some media.