H.F. resistance of round-wire single-layer inductance coils

The elements of a coil cut by two parallel planes are approximated to elements of straight parallel conductors, and equivalence between the coil and the straight parallel conductors is assumed. The resistance of the system of parallel conductors is calculated by the method described in an earlier paper by Arnold and the author. The calculated values of the resistance of the coils used by Medhurst in his experiments are compared with the experimental values of resistance. The results show agreement within 5% experimental error for coils having high values of x. This agrees with Butterworth´s theory that the field in the coil is uniform for high values of x and a large number of turns. The agreement between experimental and calculated results is therefore within the region predicted by theory when x is large. The method can thus be applied with confidence to coils at high frequencies provided that the frequency of operation is within 5% of the self-resonant frequency of the coil and x is equal or greater than 17.