Wavelengths seen in 2D plots

I am simulating the intereaction of EM radiation with a plasmonic element. I have set up the study to parametize the wavelength of the incoming radiation from 4 um to 20 um. In looking at the fields in the 2D plots, I notice that when I switch from wavelength to wavelenth, the interaction of the field with the element does change. Nevertheless, the number of field maxima and minima between the source port and the element stays the same. For example, my port is fixed at 30 um from my element. When I view the 2D plot of a 5 um incident wave I see the same number of maxima and minima in the incoming field as when I view the plot of a 10 um incident wave.

Why would that occur? Shouldn't I see twice as many maxima and minima in the 5 um plot as I do in the 10 um plot?

v/r

John