System for Measuring Thin-Film Permeabilty by Using a Parallel Line.

A method of measuring the permeability of soft magnetic films at high frequencies was investigated. The main components of this system are a network analyzer and a parallel line. We attempted to discover why the value of the given permeability by the parallel line method is less than that given by the coil impedance method. As a result, we found that the leakage of field energy outside the line must be considered in evaluating the correct permeability. The parameter a was introduced for the leakage of the field energy. We then measured the value of the permeability by the parallel line method (10 MHz∼500 MHz), and this value matched well with that measured by using a figure-of-eight permeameter (1 MHz∼100 MHz). The dimensions of the parallel line were 15 mm in length, 11.3 mm in width and 1.5 mm in depth.