Even-order harmonic distortion in AC-bias recording

Even-order harmonic distortion in ac-bias tape recording is analyzed. The dominant cause of even-order harmonic generation is a superimposed dc magnetic field in the recording process. Assuming an erf tape magnetization transfer function, approximate expressions for tape magnetization, playback head flux and equalized playback voltage distortions are derived, taking into account such factors as signal field, dc field, wavelength, tape coating thickness, tape-to-head spacing, playback gap length, record and playback equalization curves, etc. The calculated results show excellent quantitative agreement with experimental data.