Fourier-transform-infrared (FTIR) and millimeter wave(MMW)are applied to study the electromagnetic waves attenuation by the aqueous foams.Low transmission was found at 3-5 Ixm,8-14 μm and structure besides the species and its consistency play main pole of the nice attenuation.And the further performances virtues of water-solubility, adjustability,nice rheology and inexpensive make US believe that foam is a novel nice potential medium of broadband PPECM.