At much
lower frequencies, the wavelength is large enough that there is insignificant phase variation
across the dimensions of a componenl. The other extreme of frequency can be identified
as optical engineering, in which the wavelength is much shorter than the dimensions of the
component. In this case Maxwell's equations can be simplified to the geometrical optics
regime, and optical systems can be designed with the theory of geometrical optics. Such
techniques are sometimes applicable to millimeter wave systems, where they are referred
to as quasioptical.