Measurement of permeability at v.h.f. using transmission line technique

The accurate measurement of the propagation constant of a transmission line, particularly in the v.h.f. region, is severely limited by the inaccuracy inherent in the calibration of the meter used for measurement. A comparative method, due to Wieberdink, is described here, and its theory discussed. The method can be applied to the measurement of the surface impedance of a conductor, and the theory is given for specimens in the form of cylindrical wire and flat strip. From the values obtained for surface impedance, in the case of a ferro-magnetic specimen, the permeability at v.h.f. can be deduced. Some results obtained by use of this method are given for certain commercial Permalloys in the form of strip, and for nickel in the form of wire.