Measurement has been made of the spectral intensity of the harmonic zones which exist at the output of a non-linear device fed by narrowband noise and an unmodulated carrier. The spectral shape, the maximum spectral intensity, and the carrier component in each of the first six harmonic zones (l= 0…5) have been determined both theoretically and experimentally for a half-wavevth-law rectifier withv= ½, 1 and 2, for a wide range of input carrier/noise ratios.The measuring equipment is discussed in the paper, the theoretical and experimental results are compared, and a number of computed results of practical interest are presented.