A multi-layer absorber , comprising a polymeric proximal layer having a radiation-receiving surface adapted for receiving electromagnetic radiation, a polymeric distal layer disposed adjacent the proximal layer to receive at least a portion of the received radiation, if any, transmitted through said proximal layer , and a plurality of radiation absorbing additives distributed within at least one of said layers , said additives being capable of absorbing electromagnetic energy at one or more frequencies in a range of 20 GHz to 110 GHz, wherein said radiation absorbing additives comprise a plurality of carbon particles, wherein said polymeric proximal layer exhibits an index of refraction having a real part that is less than the real part of an index of refraction of said polymeric distal layer for at least one frequency of the electromagnetic radiation in a range of 20 GHz to 110 GHz, wherein the real parts of the indices of refraction of said layers at said at least one frequency satisfy the following relation: 1 ≤ n r d − n r p f ≤ 20 , wherein, n r d denotes the real part of the index of refraction of the polymeric distal layer , n r p denotes the real part of the index of refraction of the polymeric proximal layer , f (in units of GHz) denotes the frequency at which the difference in real parts of the indices of refraction of the polymeric proximal and distal layers is determined, and wherein said multi-layer absorber exhibits a reflectance coefficient less than 0.3 and a transmission coefficient less than 0.3 for incident radiation in a frequency band within said frequency range of 20 GHz to 110 GHz. a polymeric proximal layer having a radiation-receiving surface adapted for receiving electromagnetic radiation, a polymeric distal layer disposed adjacent the proximal layer to receive at least a portion of the received radiation, if any, transmitted through said proximal layer , and a plurality of radiation absorbing additives distributed within at least one of said layers , said additives being capable of absorbing electromagnetic energy at one or more frequencies in a range of 20 GHz to 110 GHz, wherein said radiation absorbing additives comprise a plurality of carbon particles, wherein said polymeric proximal layer exhibits an index of refraction having a real part that is less than the real part of an index of refraction of said polymeric distal layer for at least one frequency of the electromagnetic radiation in a range of 20 GHz to 110 GHz, wherein the real parts of the indices of refraction of said layers at said at least one frequency satisfy the following relation: 1 ≤ n r d − n r p f ≤ 20 , wherein, n r d denotes the real part of the index of refraction of the polymeric distal layer , n r p denotes the real part of the index of refraction of the polymeric proximal layer , f (in units of GHz) denotes the frequency at which the difference in real parts of the indices of refraction of the polymeric proximal and distal layers is determined, and n r d denotes the real part of the index of refraction of the polymeric distal layer , n r p denotes the real part of the index of refraction of the polymeric proximal layer , f (in units of GHz) denotes the frequency at which the difference in real parts of the indices of refraction of the polymeric proximal and distal layers is determined, and wherein said multi-layer absorber exhibits a reflectance coefficient less than 0.3 and a transmission coefficient less than 0.3 for incident radiation in a frequency band within said frequency range of 20 GHz to 110 GHz. <EOS>