New surface-wave-like mode on CPWs of infinite width and its role in explaining the leakage cancellation effect

A surface-wave-like mode on coplanar waveguides (CPWs) of infinite width is described. It is explained how the sharp minima in the leakage constant values can be understood in terms of a cancellation effect, and it is shown that the field structure in the frequency range before the minimum is different from that in the frequency range above that minimum. In fact, before the minimum the field is that of the surface-wave-like mode, and after it the field is that of the dominant CPW mode.<>