Propagation on Modulated Corrugated Rods

The velocity of surface-wave propagation on two types of axially modulated corrugated rods has been measured experimentally. Type A has a constant outer diameter and sinusoidally varying slot depth, while in type B the slot depth varies in virtue of a modulated outer diameter. In both cases the measured phase velocity is about ten per cent less than that for a uniformly corrugated rod with the average slot depth and outer diameter, but agrees within two per cent over the frequency range used with the value calculated from an analysis based on the Mathieu equation.