Search for: [Abstrakt = "The paper is concerned with one\-dimensional multilayers that exhibit multiple bands of omnidirectional reflection, which means complete reflection regardless of incidence angle and polarization. The typical quarter\-wave constraint is replaced by the stipulation that a pair of adjacent layers should have a total optical thickness of one half of wavelength. Simple approximate analytic expressions are derived for the multiple bandgaps of the half\-wave periodic structures."]