Thin, lightweight electromagnetic wave absorber

Claim 2

Means for absorbing microwave radiation incident on the surface of an object comprising, in combination; an insulating sheet, a thin film array of uniform geometric figures on a surface of said sheet, said film being composed of a material whose electrical conductivity is greater than 0.1 mho per meter, said sheet being positioned at a distance from the surface of said object substantially less than a quarter wavelength of said incident radiation as measured in free space and absorbing said incident microwave radiation.

Claim 3

Means for absorbing microwave radiation incident on the surface of an object comprising, in combination; an insulating sheet, a thin film array of uniform geometric figures on a surface of said sheet, said film being composed of a material whose electrical conductivity is greater than 0.1 mho per meter, said sheet being positioned at a distance from the surface of said object substantially less than a quarter wavelength of said incident radiation as measured in free space and absorbing said incident microwave radiation.

Claim 4

Means for absorbing microwave radiation incident on the surface of an object comprising, in combination; an insulating sheet, a thin film array of uniform geometric figures on a surface of said sheet, said film being composed of a material whose electrical conductivity is greater than 0.1 mho per meter, said sheet being positioned at a distance from the surface of said object substantially less than a quarter wavelength of said incident radiation as measured in free space and absorbing said incident microwave radiation.

Claim 5

Means for reducing reflection of microwave radiation incident on the surface of an object comprising, in combination; an insulating sheet, a thin film array of uniform geometric figures of an electrically conducting material on said sheet, said film having a thickness in the range of about 200 to 2000 Angstroms, said sheet being positioned at a distance from the surface of said object substantially less than a quarter wavelength of said incident radiation as measured in free space to reduce reflections of said incident microwave radiation.

Claim 6

Means for reducing reflection of microwave radiation incident on the surface of an object comprising, in combination; an insulating sheet, a thin film array of uniform geometric figures of an electrically conducting material on said sheet, said film having a thickness in the range of about 200 to 2000 Angstroms, said sheet being positioned at a distance from the surface of said object substantially less than a quarter wavelength of said incident radiation as measured in free space to reduce reflections of said incident microwave radiation.

Claim 7

Means for reducing reflections of microwave radiation incident on the surface of an object comprising, in combination; an insulating sheet, a thin film array of uniform geometric figures of a semi-conductive material on said sheet, said film having a thickness in the range of about 200 to 2000 Angstroms, said sheet being positioned at a distance from the surface of said object substantially less than a quarter wavelength of said incident radiation as measured in free space to reduce reflections of said incident radiation.

Claim 8

Means for reducing reflections of microwave radiation incident on the surface of an object comprising, in combination; an insulating sheet, a thin film array of uniform geometric figures of a semi-conductive material on said sheet, said film having a thickness in the range of about 200 to 2000 Angstroms, said sheet being positioned at a distance from the surface of said object substantially less than a quarter wavelength of said incident radiation as measured in free space to reduce reflections of said incident radiation.

Claim 9

An absorber for reducing reflection of microwave radiation incident on the surface of an object comprising, an insulating sheet, a thin film array of uniform geometric figures on a surface of said sheet, said film being composed of a metallic deposit having a thickness in the range of about 200 to 2000 Angstroms, said Sheet being adapted to be positioned near the surface of an object and means for supporting said sheet at a distance from said surface substantially less than a quarter wavelength of the radiation as measured in free space.

Claim 10

An absorber for reducing reflection of microwave radiation incident on the surface of an object comprising, an insulating sheet, a thin film array of uniform geometric figures on a surface of said sheet, said film being composed of a metallic deposit having a thickness in the range of about 200 to 2000 Angstroms, said Sheet being adapted to be positioned near the surface of an object and means for supporting said sheet at a distance from said surface substantially less than a quarter wavelength of the radiation as measured in free space.

Claim 11

The absorber of claim 4 in which said means comprises an intermediate layer between said sheet and said surface, said layer being composed of a material of relatively low dielectric constant.

Claim 12

An absorber for reducing reflection of microwave radiation incident on the surface of an object comprising, a plurality of layers consisting essentially of an insulating sheet and a thin film array of closely packed squares of an electrically conducting material on said sheet, said layers being adapted to be positioned near the surface of an object, and means for supporting said layers at a distance from said surface substantially less than a quarter wavelength of the radiation as measured in free space.

Claim 13

An absorber for reducing reflection of microwave radiation incident on the surface of an object comprising, a plurality of layers consisting essentially of an insulating sheet and a thin film array of closely packed squares of an electrically conducting material on said sheet, said layers being adapted to be positioned near the surface of an object, and means for supporting said layers at a distance from said surface substantially less than a quarter wavelength of the radiation as measured in free space.

Claim 14

The absorber of claim 6 in which said means consists of a layer of mixed ferrite.

Claim 15

The absorber of claim 6 in which said means consists of a layer of rubber impregnated with carbonyl iron.

Claim 16

An absorber for reducing reflection of microwave radiation incident on the surface of an object comprising, a plurality of contiguous layers, each of said layers consisting essentially of an insulating sheet and a thin film array of closely packed squares on said sheet, said squares being formed of a material whose electrical conductivity is greater than 0.1 mho per meter, said layers being adapted to be positioned near the surface of an object and a layer of a material of relatively low dielectric constant for supporting said layers at a distance from said surface substantially less than a quarter wavelength of the radiation as measured in free space.

Claim 17

An absorber for reducing reflection of microwave radiation incident on the surface of an object comprising, a plurality of contiguous layers, each of said layers consisting essentially of an insulating sheet and a thin film array of closely packed squares on said sheet, said squares being formed of a material whose electrical conductivity is greater than 0.1 mho per meter, said layers being adapted to be positioned near the surface of an object and a layer of a material of relatively low dielectric constant for supporting said layers at a distance from said surface substantially less than a quarter wavelength of the radiation as measured in free space.

Claim 18

An absorber for reducing reflection of microwave radiation incident on the surface of an object comprising, a plurality of contiguous layers, each of said layers consisting essentially of an insulating sheet and a thin film array of closely packed squares on said sheet, said film being composed of a metallic deposit having a thickness in the range of about 200 to 2000 Angstroms, said layers being adapted to be positioned near the surface of an object, a conductive sheet of appropriate resistivity continguous to said layers and a layer of material of relatively low dielectric constant for supporting said layers and said sheet at a distance from said surface substantially less than a quarter wavelength of the radiation as measured in free space.

Claim 19

An absorber for reducing reflection of microwave radiation incident on the surface of an object comprising, a plurality of contiguous layers, each of said layers consisting essentially of an insulating sheet and a thin film array of closely packed squares on said sheet, said film being composed of a metallic deposit having a thickness in the range of about 200 to 2000 Angstroms, said layers being adapted to be positioned near the surface of an object, a conductive sheet of appropriate resistivity continguous to said layers and a layer of material of relatively low dielectric constant for supporting said layers and said sheet at a distance from said surface substantially less than a quarter wavelength of the radiation as measured in free space.

Claim 20

An absorber for reducing reflection of microwave radiation incident on the surface of an object comprising, a plurality of contiguous layers, each of said layers consisting essentially of an insulating sheet and a thin film array of closely packed squares on said sheet, said film being composed of a material whose electrical conductivity is greater than 0.1 mho per meter and having a thickness in the range of about 500 to 1200 Angstroms, said layers being adapted to be positioned near the surface of an object, a conductive sheet of appropriate resistivity contiguous to said layers and a layer of polymeric foam for supporting said layers and said sheet at a distance from said surface substantially less than a quarter wavelength of the radiation as measured in free space.

Claim 21

An absorber for reducing reflection of microwave radiation incident on the surface of an object comprising, a plurality of contiguous layers, each of said layers consisting essentially of an insulating sheet and a thin film array of closely packed squares on said sheet, said film being composed of a material whose electrical conductivity is greater than 0.1 mho per meter and having a thickness in the range of about 500 to 1200 Angstroms, said layers being adapted to be positioned near the surface of an object, a conductive sheet of appropriate resistivity contiguous to said layers and a layer of polymeric foam for supporting said layers and said sheet at a distance from said surface substantially less than a quarter wavelength of the radiation as measured in free space.

Claim 22

An absorber for reducing reflection of microwave radiation incident on the surface of an object comprising, a plurality of contiguous layers, each of said layers consisting essentially of an insulating sheet and a thin film array of closely packed squares on said sheet, at least one of said layers having said film formed of a semiconductive deposit, the rest of said layers having said film formed of a metallic deposit, said semiconductive and said metallic film having a thickness in the range of about 200 to 2000 Angstroms, said layers being adapted to be positioned near the surface of an object, a carbon-coated conductive sheet of appropriate resistivity contiguous to said layers and a layer of cellular cellulose acetate for supporting said layers and said sheet at a distance from said surface substantially less than a quarter wavelength of the radiation as measured in free space.

Claim 23

An absorber for reducing reflection of microwave radiation incident on the surface of an object comprising, a plurality of contiguous layers, each of said layers consisting essentially of an insulating sheet and a thin film array of closely packed squares on said sheet, at least one of said layers having said film formed of a semiconductive deposit, the rest of said layers having said film formed of a metallic deposit, said semiconductive and said metallic film having a thickness in the range of about 200 to 2000 Angstroms, said layers being adapted to be positioned near the surface of an object, a carbon-coated conductive sheet of appropriate resistivity contiguous to said layers and a layer of cellular cellulose acetate for supporting said layers and said sheet at a distance from said surface substantially less than a quarter wavelength of the radiation as measured in free space.

Claim 24

The absorber of claim 12 in which said plurality of layers consist of a layer of polyethylene having on the surface thereof a deposit of indium antimonide of about 1200 Angstroms in thickness and three layers of polyethylene having on the surface thereof a deposit of aluminum of about 1000 Angstroms in thickness and in which said layer of cellular cellulose acetate has a thickness of approximately 2.5 cm.