PRINCIPLES AND HEAD CHARACTERISTICS IN VHF RECORDING

Abstract

Concepts of VHF analog magnetic recording are discussed; problem areas are reviewed; and solutions are outlined. Attention is drawn to the conductive-gap-spacer recording head. The unique field contours of this recording head with Alfesil pole faces are analyzed in relation to the recording of very short wavelengths. The field gradients of the unloaded head are computed for various conditions such as maximum magnetization depths, positions in the tape coating, and gap lengths. Comparison of the driven-gap-spacer head using Alfesil pole faces with the ferrite driven-gap-spacer head and the conventional ring-core head shows the Alfesil type to be the most effective for a-c bias VHF recording at very short wavelengths. Problems associated with short-wavelength recording and reproduction are reviewed. In spite of good short-wavelengths capabilities of the Alfesil head, the requirement for a high head-to-tape speed continues to be mandatory to minimize wavelength reproduction losses.