Most present day wideband magnetic tape recorders utilize a FM system for encoding and decoding the information applied to the tape. In the past FM has been employed for reasons of linearity and to avoid the amplitude modulation which occurs due to varying head-to-tape contact. Recent developments in heads, tapes, and transports, however, have removed many of the constraints which originally forced the use of a FM system. Consideration of a high-frequency bias system for video and wideband instrumentation recorders, therefore, is again made possible. As a direct recording system holds so much promise in the areas of linearity and distortion properties, it becomes necessary to establish the transfer function for tape when it is acted upon by a high-frequency bias. The purpose of this paper is to develop a method that may be used to establish the feasibility of such a system and to set down its physical and magnetic parameters. A three-dimensional magnetic moment distribution function J(H+, H−) is used to describe the magnetic properties of the tape. Then the actual transfer characteristics of the headtape system are developed by applying the magnetic field about the record head to the three-dimensional distribution function J(H+, H−).