US5202688A — Bulk RF absorber apparatus and method

Claim 1

Independent Claim 91 words

An electromagnetic radiation absorber, comprising: a block of a reticulated dielectric material having a predetermined surface for receiving incident radiation to be absorbed, said block being formed of a plurality of randomly oriented filaments of the dielectric material; and at least one layer of electromagnetic radiation absorbing material on each of said plurality of filaments of said block, the radiation absorptivity of said at least one absorbing material layer varying in accordance with a predetermined function along a gradient direction that is at a predetermined angle relative to said predetermined surface.

Claim 2

Dependent Claim 91 words

An electromagnetic radiation absorber, comprising: a block of a reticulated dielectric material having a predetermined surface for receiving incident radiation to be absorbed, said block being formed of a plurality of randomly oriented filaments of the dielectric material; and at least one layer of electromagnetic radiation absorbing material on each of said plurality of filaments of said block, the radiation absorptivity of said at least one absorbing material layer varying in accordance with a predetermined function along a gradient direction that is at a predetermined angle relative to said predetermined surface.

Claim 3

Dependent Claim 31 words

The radiation absorber of claim 1 wherein the radiation absorptivity of said at least one absorbing material layer in said block varies along a direction substantially perpendicular to said predetermined surface.

Claim 4

Dependent Claim 36 words

The radiation absorber of claim 1 wherein said at least one absorbing material layer is electrically conductive; and the radiation absorptivity of said at least one absorbing material layer being varied by varying the thickness thereof.

Claim 5

Dependent Claim 39 words

The radiation absorber of claim 3 wherein said at least one layer of electrically conductive material is primarily composed of a material selected from the group consisting of aluminum, copper, silver, monel, inconel, permalloy, palladium, gold, nickel and nichrome.

Claim 6

Dependent Claim 52 words

The radiation absorber of claim 1 further including at least another layer of electromagnetic radiation absorbing material to comprise a plurality of layers on at least a portion of said filaments, the radiation absorptivity of each said absorbing material layer varying in accordance with a corresponding predetermined function along the gradient direction.

Claim 7

Dependent Claim 21 words

The radiation absorber of claim 5 wherein each of said plurality of layers of absorbing material is an electrically conductive material.

Claim 8

Dependent Claim 23 words

The radiation absorber of claim 1 further including a protective layer of dielectric material applied over said at least one absorbing material layer.

Claim 9

Dependent Claim 17 words

The radiation absorber of claim 1 wherein said block of dielectric material has a substantially rectangular shape.

Claim 10

Dependent Claim 15 words

The radiation absorber of claim 1 wherein said predetermined surface includes a predetermined relief pattern.

Claim 11

Dependent Claim 58 words

The radiation absorber of claim 1 wherein said predetermined surface is substantially planar; said radiation absorber including an uncoated sheet of said dielectric material having a first planar surface positioned in contact with said predetermined surface, a second surface of the uncoated sheet opposing said first planar surface having a predetermined relief pattern presented for receiving incident radiation.

Claim 12

Dependent Claim 128 words

An electromagnetic radiation absorber, comprising: a plurality of sheets of a reticulated dielectric material having respective face surfaces in contact with one another, each of said plurality of sheets being formed of a plurality of randomly oriented filaments of the dielectric material, each of said plurality of sheets of said radiation absorber being oriented to present an edge surface for receiving incident radiation to be absorbed; and at least one layer of electromagnetic radiation absorbing material coating each of said filaments of each of said pluraltiy of sheets, the radiation absorptivity of said at least one absorbing material layer varying in accordance with a predetermined function along a gradient direction that is substantially parallel to said face surface and at a predetermined angle relative to said edge surface.

Claim 13

Dependent Claim 128 words

An electromagnetic radiation absorber, comprising: a plurality of sheets of a reticulated dielectric material having respective face surfaces in contact with one another, each of said plurality of sheets being formed of a plurality of randomly oriented filaments of the dielectric material, each of said plurality of sheets of said radiation absorber being oriented to present an edge surface for receiving incident radiation to be absorbed; and at least one layer of electromagnetic radiation absorbing material coating each of said filaments of each of said pluraltiy of sheets, the radiation absorptivity of said at least one absorbing material layer varying in accordance with a predetermined function along a gradient direction that is substantially parallel to said face surface and at a predetermined angle relative to said edge surface.

Claim 14

Dependent Claim 47 words

The radiation absorber of claim 11 wherein the variation of radiation absorptivity corresponds to a predetermined radiation absorption gradient; and each said sheet of dielectric material having substantially the same absorption gradient, the respective sheets being oriented to achieve a predetermined alignment between their respective absorption gradients.

Claim 15

Dependent Claim 32 words

The radiation absorber of claim 11 wherein the radiation absorptivity of said at least one absorbing material layer in each said sheet varies along a direction substantially perpendicular to said edge surface.

Claim 16

Dependent Claim 36 words

The radiation absorber of claim 11 wherein said at least one absorbing material layer is electrically conductive; and the radiation absorptivity of said at least one absorbing material layer being varied by varying the thickness thereof.

Claim 17

Dependent Claim 39 words

The radiation absorber of claim 14 wherein said at least one layer of electrically conductive material is primarily composed of a material selected from the group consisting of aluminum, palladium, gold, nickel, nichrome, copper, silver, monel, inconel and permalloy.

Claim 18

Dependent Claim 52 words

The radiation absorber of claim 11 further including at least another layer of electromagnetic radiation absorbing material to comprise a plurality of layers on at least a portion of said filaments, the radiation absorptivity of each said absorbing material layer varying in accordance with a corresponding predetermined function along the gradient direction.

Claim 19

Dependent Claim 21 words

The radiation absorber of claim 16 each of wherein said plurality of layers of absorbing material is an electrically conductive material.

Claim 20

Dependent Claim 25 words

The radiation absorber of claim 11 wherein each said sheet of dielectric material is composed of a plurality of absorptivity regions along the gradient direction.

Claim 21

Dependent Claim 32 words

The radiation absorber of claim 18 wherein the absorbing material contained in at least one of said absorptivity regions differs from the absorbing material contained in another one of said absorptivity regions.

Claim 22

Dependent Claim 23 words

The radiation absorber of claim 11 further including a protective layer of dielectric material applied over said at least one absorbing material layer.

Claim 23

Dependent Claim 33 words

The radiation absorber of claim 20 wherein said protective layer of material also acts as a bonding agent to bond the respective face surfaces of said sheets of dielectric material to one another.

Claim 24

Dependent Claim 48 words

The absorber of claim 11 wherein said sheets are aligned so that the respective edge surfaces are adjacent to one another and form a radiation absorbing face of said radiation absorber; and said edge surfaces being configured to form a predetermined relief pattern on said radiation absorbing face.

Claim 25

Dependent Claim 80 words

The absorber of claim 11 wherein said sheets are aligned so that the respective edge surfaces are adjacent to one another and form a planar radiation absorbing face of said radiation absorber; and said radiation absorber further including an uncoated sheet of said dielectric material having a first planar surface positioned in contact with said radiation absorbing face, a second surface of the uncoated sheet opposing said first planar surface having a predetermined relief pattern presented for receiving incident radiation.

Claim 26

Dependent Claim 149 words

An electromagnetic radiation absorber comprising: a plurality of substantially rectangular sheets of reticulated dielectric material having respective face surfaces predeterminedly aligned and in contact with one another, each said sheet being formed of a pluraltiy of randomly oriented filaments of the dielectric material, each said sheet having a planar edge surface for receiving incident radiation to be absorbed, said edge surface being substantially perpendicular to said face surfaces, said sheets being aligned so that the respective edge surfaces are adjacent to one another and form a planar absorbing face of said radiation absorber; and at least one layer of electromagnetic radiation absorbing material on each of said filaments of each said sheet, the radiation absorptivity of said at least one absorbing material layer varying in accordance with a predetermined function along a gradient direction that is substantially parallel to said face surfaces and substatially perpendicular to said edge surface.

Claim 27

Dependent Claim 149 words

An electromagnetic radiation absorber comprising: a plurality of substantially rectangular sheets of reticulated dielectric material having respective face surfaces predeterminedly aligned and in contact with one another, each said sheet being formed of a pluraltiy of randomly oriented filaments of the dielectric material, each said sheet having a planar edge surface for receiving incident radiation to be absorbed, said edge surface being substantially perpendicular to said face surfaces, said sheets being aligned so that the respective edge surfaces are adjacent to one another and form a planar absorbing face of said radiation absorber; and at least one layer of electromagnetic radiation absorbing material on each of said filaments of each said sheet, the radiation absorptivity of said at least one absorbing material layer varying in accordance with a predetermined function along a gradient direction that is substantially parallel to said face surfaces and substatially perpendicular to said edge surface.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1996-04-12	1996-10-12	1997-04-13	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2000-04-12	2000-10-12	2001-04-13	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2004-04-12	2004-10-12	2005-04-13	$7700.00	Window Closed / Lapsed

Bulk RF absorber apparatus and method

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