Abstract: A stable dark or moderately dark opaque exterior coating constituted of pentations and binder materials having low solar absorbing properties capable of visual and infrared camouflage. The pigmentations and binder materials may be selected for the proper optical qualities by previous testing before mixture and application as a coating.

Abstract: A fin blanket for attenuating radio-frequency scattering, thereby protecting a surface such as a feed-horn or radiator panels of a spacecraft. The fin blanket includes a plurality of fins formed of a microwave absorbing film, each fin including at least one planar side positioned generally parallel to an electric field formed by the radio-frequency scattering.

Abstract: The composite according to the invention comprises a stack of alternately ferromagnetic and insulating, thin layers (12, 14) receiving on their edge the electromagnetic field to be transformed.

Abstract: Novel test mounts are defined for a radar cross section testing apparatus that allows a supported object to be tested without interference from the test mount. This includes prescribing a diameter of about 0.61 wavelengths for a cylindrical test mount; maintaining a ratio for the test mount's characteristic dielectric constant and magnetic permeability of about one; and/or installing a frequency transposing apparatus to convert the frequency of radar pulses directed toward the test mount to off-frequency echoes.

Abstract: An apparatus for attenuating traveling wave reflections from a surface, due to an impedance mismatch between the surface and free space. The apparatus includes a resistive element having an impedance between that of the surface and free space. The resistive element is positionable relative to the surface so as to minimize the impedance mismatch between the surface and free space. The resistive element is preferably a resistively graded element, which includes a forward end with an impedance approaching the impedance of the surface. An aft end of the resistively graded element has a high impedance relative to free space. The aft end is positionable sufficiently distant from the surface so as to minimize any traveling wave reflection due to impedance mismatch between the surface and free space.

Abstract: A wave absorber comprising a sintered ferrite tile wave absorber as a base substrate lowermost relative to the incident wave, and one or more laminates comprising two layers as one set, with a dielectric layer as a lower layer and a dielectric loss-causing layer as an upper layer, laminated on the base substrate. The wave absorber of the present invention is thin, but is capable of absorbing waves over wide frequency bands of from tens of megahertz to a dozen or so gigahertz. By making the absorber thin, the absorber weighs less and is easy to handle, which in turn leads to fine workability and low construction cost.

Abstract: An EMR-absorbing anechoic chamber absorber (22, 42) uses a block of honeycomb material with a lossy material, such as carbon, applied to the sheets (4) of material from which the honeycomb is made to create wedges (36) or pyramids (44) of lossy material. Preferably, the lossy material is applied to the sheets of material in a repeating wedge-shaped pattern (16) to create the wedges of lossy material within the solid rectangular block of honeycomb material. Parallel, wedge-shaped grooves (43) are formed in the block of honeycomb material to create the pyramids of lossy material. If the lossy material is applied to the entire sheet, a set of parallel, wedge-shaped grooves are formed in the block of honeycomb material to create wedges of lossy material; two sets of parallel, wedge-shaped grooves are formed at 90.degree. angles to one another to create pyramids of lossy material.

Abstract: In a radar absorbing material, first or relatively resistive fibers are combined with second or relatively conductive fibers in a dielectric binder. Preferably, the first fibers are graphite filaments and the second fibers are metal coated graphite filaments. The appropriate selection of fibers results in a material having broadband or multi-frequency RF absorbing properties.

Abstract: A millimeter wave screening cloud-forming product is made by forming comped hollow disks of carbon fiber cut to a desired length. The handleable disks are stacked inside a grenade body forming a hollow cylindrical shape. A high explosive mass is inserted into the resulting compacted hollow cylinder, enabling bursting of the compacted mass to release the individual carbon fibers.

Abstract: An apparatus for providing broadbanded electromagnetic radiation attenuation is disclosed. The apparatus comprises a surface mount to which a plurality of protuberances are mounted. Each protuberance is further made up of a plurality of impedance sheets that are substantially concentric one with another. The impedance sheets are directionally shaped so as to enhance absorption of any polarization of plane wave radiation from any incidence direction including near grazing incidence. The impedance sheets have impedance values which are tapered with higher impedance values belonging to the sheets farther away from the concentric center. These sheets may be either substantially spherical, hemispherical, or circular cylinders. The distance separating neighboring impedance sheets is selected according to the shortest wavelength for which good electromagnetic attentuation is desired.

Abstract: A method is disclosed for making a microwave radar transparent window material operable at temperatures above 2000.degree. C., and which material possesses high tensile strength, is resistant to .erosion as well as particle impact at such temperatures, and is highly machinable. The method comprises: blending a powder mixture of 20-60% by weight silicon nitride, 12-40% boron nitride, 15-40% boron nitride, 15-40% silica, and 1-20% oxygen carrying sintering aids; (b) molding the mixture to shape as a preform; and (c) densifying the shaped preform into a monolithic window having high temperature stability and transparency at high temperatures.

Abstract: An attenuator of electromagnetic radiation, such as radar, is described wherein a single attenuator sheet in the nature of "spacecloth" is placed in front of a plurality of reflective layers wherein each of the reflective layers is tuned to reflect a narrow band of radiation of a selected frequency and transmit other frequencies; and each of the reflective layers is spaced from the attenuation layer at a distance of one-fourth of the wavelength of electromagnetic radiation to which it is tuned. In a preferred embodiment each of the reflective layers comprises elongated narrow conductive areas arranged in spaced apart columns and rows in a generally non-conductive area.

Abstract: A broad-band radio wave absorber is disclosed which includes a radio wave reflecting surface, and a plurality of magnetic members provided on the reflecting surface and arranged in columns and rows in the directions of X- and Y-axes, each of the magnetic members having a first section extending in parallel with the Y-axis and a second section in contact with the first section throughout the height thereof and extending in parallel with the X-axis, such that the first sections in each column and the second sections in each row are spaced apart from each other at a predetermined distance. Each of the first and second sections has a part having a length which is smaller than the distance at which each adjacent two sections are spaced apart, so that there is formed an aperture between each of the two adjacent sections.

Abstract: A hybrid-type wide band electromagnetic wave absorber having cone-shaped projections of a reduced may be produced by matching the impedance of the cone-shaped absorber members and the underlying plate type absorber. Such a hybrid-type wide band electromagnetic wave absorber is formed by arranging tapered cone-shaped members in a regular pattern on a sintered ferrite plate, which is disposed on a metal plate. The cone-shaped members are formed of a material selected from a ferrite and a ferrite composite and each have a normalized cross-sectional area at the base of 0<S.sub.0 <1 and an exponent of cone shape of 0<n<10. Such a hybrid type electromagnetic wave absorber may be used, for example, for performing EMI/EMS testing in an anechoic chamber in the frequency range of 30 MHz to 1 GHz. In the case of applications such as antenna testing in the frequency range of 30 MHz to 30 GHz, the height of the cone-shaped members must be appropriately increased.

Abstract: A broadband absorber for absorbing a broad spectrum of incident microwave radiation is provided comprising a plurality of strips of inductive absorbing material having magnetic particles dispersed throughout an organic binder; the width, thickness, and composition of the strips being selected such that each strip absorbs a specific region of the microwave spectrum. The plurality of strips of absorbing material are supported by a substrate that is electrically conductive to microwave radiation. The substrate has a plurality of grooves and ridges in a repeating pattern, the grooves being of varying depths. A facing sheet, electrically transparent to microwave radiation, is provided for coupling the incident microwave radiation to the plurality of strips of inductive absorbing material.

Abstract: A radar absorbing holster for use with an electromagnetic radiation generating device is disclosed. The radar absorbing holster comprises a rigid housing having a closed end and an open end defining an inner cavity. The housing has electromagnetically reflective properties, and an electromagnetically absorbing foam layer that is disposed on the inner surface of the housing.

Abstract: An anechoic chamber has a structure in which a dielectric plate is interposed between an electromagnetic shielding metal plate provided on an interior surface of the chamber and ferrite tiles serving as wave absorbing members, such that the ferrite tiles are located on an interior-side surface of the chamber. Screws serving as metal fittings are secured onto the electromagnetic shielding metal plate, and the dielectric plate is reliably attached to the metal plate by making use of the screws. Alternatively, the dielectric plates are attached to the steel sheet by means of adhesive such that the dimensions of each dielectric plate is made sufficiently smaller than those of a fixed size.

Abstract: An ultra hard, wideband anti-reflection coating for an IR window, such as GaAs, which resists environmental and chemical attack. The coating is designed to allow spectral transmission therethrough in a wide band, namely the 3 to 12 micron range. A cladding layer is formed on the GaAs window. A first diamond like carbon (DLC) layer is then formed on the first bonding layer. A bonding layer is formed on the first DLC layer and a second DLC layer is formed on the bonding layer.

Abstract: This invention relates to a broad bandwidth electromagnetic wave absorber comprising a sintered ferrite and a CuO--Fe.sub.2 O.sub.3 system. The CuO--Fe.sub.2 O.sub.3 system, a spinel ferrite, has its own magnetic property, which makes it possible to be used for an electromagnetic wave absorber. The CuO--Fe.sub.2 O.sub.3 system is preferentially located at the grain boundary in the matrix ferrite. This resulted in increase in the total loss, decrease in matching thickness and shift in the center frequency.

Abstract: The invention pertains to a process to fasten an intrinsic element absorbing electromagnetic waves onto a wall of a structure or infrastructure.The process of the invention consists of coating a surface of a wall of a structure by means of a syntactic foam with the rheologic properties of a mastic and being transparent to electromagnetic waves, then placing an element absorbing electromagnetic waves into or onto the syntactic foam coating, and letting the syntactic foam harden. The process can be used to place an element absorbing electromagnetic waves onto surfaces of any shape and in a simple manner without requiring special equipment.

Abstract: A radar absorbing apparatus for use with an electromagnetic radiation generating device is disclosed. The radar absorbing apparatus comprises a rigid housing having a closed end and an open end defining an inner cavity. The open end is formed to have a peripheral edge dimensioned to mate to the interior surface of a motor vehicle window. The housing has electromagnetically reflective properties. In addition, the housing has an aperture that extends through the closed end of the housing that communicates with the cavity. This aperture is dimensioned to receive an operative end of the electromagnetic radiation generating device. The apparatus further includes an electromagnetically absorbing layer that is disposed on the inner surface of the housing.

Abstract: A radar cross-section reduction system utilizes a charging device for creating a high positive DC static potential on an object such as an aircraft. The charging system is mounted to the object so that this DC potential would be applied to the outer skin or surface of the object. The charging system includes Van de Graaf generators located in housings attached to the object. Each Van de Graaf generator has two pulleys about which a belt is rotated. One of the pulleys and the belt are nonconductors, while the other pulley is a conductor. This results in a buildup of positive charges at one end of the belt and negative charges at the other end. The negative charges are picked off and applied to a ground section. The positive charges are picked off and applied to a collector. The collector is in electrical continuity with the outer structure of the object. Negative dissipators attached to the ground section dissipate the excess negative charges during flight.

Abstract: A microwave absorber in a pointed shape, including a phenol resin foam containing a dielectric loss material, is prepared by setting an incombustible sheet container of a same shape in a mold in a pointed shape, pouring the phenol resin to which the dielectric loss material is blended, and foaming and curing. As a result, a semi-incombustible or incombustible microwave absorber of high strength possessing a high microwave absorption capacity in a wideband is obtained.

Abstract: A broad-band radio wave absorber with a plurality of pieces of a magnetic member disposed parallel to each other or in a crosswise way on a reflecting plate. Each of the pieces of the magnetic member is configured in such a manner that its thickness is arranged so as to become smaller from its bottom toward its top in a stepwise fashion and that so as to be longer than its bottom thickness. Further, each of the pieces of the magnetic member is disposed in a relationship spaced away from the adjacent pieces thereof in such a predetermined distance longer than the bottom thickness of each piece thereof.

Abstract: A method for making a material with an artificial dielectric constant is carried out by choosing the desired dielectric constant for a particular electromagnetic field, selecting a substantially non-electrically conductive sheet material (2) from which the cellular core material (26) is to be made, applying an electrically conductive material (8) to selected areas on the sheet material and thereafter forming a cellular core material from layers of the sheet material having the conductive material already applied thereto.

Abstract: A ultrablack article made of a resin containing light absorbing pigments or dyes and its method of manufacture. The surface of the article is provided with light reflecting projections that cause incident light to reflect from the sides of such projections at least twice and preferably at least three times before reflecting from the articles surface. The vast majority of the incident light is thereby transmitted into the article where it is absorbed. The projections are advantageously conical, pyramidal or ridge shaped. The total incident light that reflects from the surface and from the interior of the article is not greater than 0.5%.The surface can be made by applying cone or pyramid shaped light beams to photoresist stepwise to make cones and pyramids and by scanning to make ridges. Means are provided to transfer such surfaces to more suitable resins and to do so continuously.

Abstract: An electromagnetic wave absorber has a pair of electromagnetic wave absorbing plates (10,11) made of ohmic resistance loss material with top portions (10a,11a) and bottom portions (10b,11b), and a common bottom support member (12) for supporting the bottom portions (10b,11b) of the plates (10,11). In assembled state, the top portions (10a,11a) of the plates (10,11) are fixed with each other and the bottom portions (10b,11b) of the plates (10,11) are fixed by the bottom support member (12) so that the plates (10,11) form an wedge shape.

Abstract: A high temperature, high strength in-situ reinforced ceramic composite adapted for use in various applications including missile radomes in which microwave transparency is required in a high temperature environment. The material is manufactured by a pressureless sintering process, in which silicon nitride and barium aluminosilicate are blended together, isostatically pressed into a desired shape and thereafter sintered.

Abstract: A door assembly system for a shielding enclosure capable of attenuating RFI and EMI emissions, comprising of a separable waveguide attenuator structure assembly with triple track rails and channels for the disposition of electromagnets separately wound and energized, peripherally formed around the door casing member, inwhich is engaged with a door leaf member when in a closed position. Electromagnets are operatively connected and directly wired without the need for electronic filtering devices to the electronic control box unit located inside enclosure. Exterior door leaf sheet and trim are welded or preferably removable enabling the addition of security components and replacement of parts. A automatic door closure device pulls the door leaf members into close proximity to the pole faces of waveguide structure, which engages a switch to activate the electromagnets.

Abstract: A method and apparatus for traveling wave attenuation measurement in the UHF and VHF frequency bands. The test set up comprises a ramp structure located in the quiet zone of a parallel plate set up. The RAM specimen to be tested is attached to the top ramp surface starting at the highest point of the ramp. The time domain signal is gated to reject all scattering except the contribution from the ramp surface. The inverse Fourier transform of the gated time data results in the frequency response of the ramp. The RCS from ramp with RAM material attached is normalized to that of the perfectly conducting surface to provide a relative attenuation of the surface traveling wave.

Abstract: Ferrites as an electromagnetic wave absorber have their unique attenuation ranges depending on their compositions. The possibility of controlling attenuation characteristics of ferrite absorber by forming laminates of ferrite is disclosed. This invention provides that the center frequency of laminated ferrites could be changed arbitrarily employing ferrite with different composition and thickness. The method consists of stacking at least two soft ferrite layers (Ni-Zn, Mn-Zn) with various thickness.

Abstract: A calibration reference target fixture is mounted on a pylon having a motorized spline extending longitudinally therethrough. The body of the fixture is teardrop shaped so as to present a low reflection cross section to a transmitting antenna. The reference target itself is a hinge-mounted plate which is driven by cam means connected to the motorized spline for selectively moving the plate between a deployed exposed position and a stored position, within the recess of the fixture body.

Abstract: A tunable high-frequency device using a superconductive thin layer with a thickness smaller than the thickness of penetration of a magnetic field is positioned on a dielectric layer. Also included is a means for varying the density of the Cooper pairs of the superconductive thin layer.

Abstract: Ingredients of loaded dielectric media are specified for the achievement of high absorption and/or high reflection of electromagnetic power over very broad frequency bands and with very low material mass requirements on the absorbing or reflecting agents. The loading consists of dilute distributions of small metallic particles specified in terms of their individual properties, namely electrical conductivity, permeability, size, shape, and their collective properties, i.e., number densities, metallic volume fractions. The required permittivities of sustaining dielectrics and the thicknesses or penetration depths for absorption or reflection of the loaded media are also specified. These particulate and supporting dielectric properties are scaled with respect to the electromagnetic wavelength or frequency bands for the achievement of the desired percentage power absorption and/or reflection (in nonoverlapping bands). The invention applies to all frequencies below visible optical.

Abstract: The provision of of an electromagnetic wave absorbing apparatus having a broadband electromagnetic wave absorbing characteristic, and which can also be used for the improvement of existing electromagnetic wave absorbing apparatus. Successive layers of an sintered ferrite magnetic body (F), a dielectric body (D) having a low permittivity, and a magnetic body (RF) having a low magnetic permeability, are overlapped on a flat reflector plate, and the relationship between the magnetic permeability .mu.1 of the sintered ferrite magnetic body and the magnetic permeability of the magnetic body having a low magnetic permeability is .mu.1.gtoreq.25.multidot..mu.2.

Abstract: The present invention relates to a broad-band wave absorber wherein beams (3) formed of a ferrite magnetic material are placed at an optimal spacing and are aligned in a lattice form in longitudinal and lateral directions on a conductive plate (2). A magnetic substance of a specific thickness t.sub.m is formed into cylindrical blocks of a height d (where d.gtoreq.t.sub.m) wherein an end surface thereof is polygonal, and the cylindrical blocks are provided with a radio-wave reflecting surface aligned in such a manner that this surface is perpendicular to the axial direction of the blocks, and the end surface of the blocks is approximately perpendicular to a direction from which radio waves are incident. The ferrite magnetic substance could also be formed into rectangular prisms of thickness 2t.sub.

Abstract: Radar echo reduction in an aircraft and the like provides a radar reflective rear edge that is independent of the configuration of a main wing or the like. In a particular object required to suppress radar echoes such as, for example, an aircraft, a ship such as a warship, a special vehicle, a bridge or the like, the radar echo reduction constituent is a conductive thin layer equipped on an outer surface of the object and having its terminal rear edge oriented obliquely to the expected direction of an incoming radar wave.

Abstract: An absorbing assembly for absorbing electromagnetic radiation in the range 10 MHz to 100 GHz comprises a lossy dielectric material and chiral elements disposed outside the lossy dielectric. The chiral elements may be springs, Mobius bands, irregular tetrahedra, tapering helical springs or handed non-planar forks. The lossy dielectric material may be in the form of a shaped structure e.g. for use in an anechoic chamber.

Abstract: A radar absorbing material comprising multiple layers integrated to form a thin, flexible, and lightweight structure. The material includes a substrate having disposed thereon absorber elements that are resistively loaded to enable one to construct a device relatively small and thin size. The broadbanding of the device is carried out by multilayering concepts in which different size antenna patterns are multilayered with each layer designed to absorb frequencies in a specified range. The absorber elements are selected for their intrinsic impedance properties and preferrably be polarization insensitive. These absorber elements are disposed in a random and preferrably aperiodic pattern.

Abstract: Electromagnetic absorber having serrations on a surface or surfaces thereof to reduce reflectivity of incident electromagnetic waves thereon. The serrations form a plurality of fins, the height of adjacent fins being spaced by a small distance. Preferably the total absorber wedge height is greater than about 1 wavelength at the lowest design frequency and the height between the serration tips is less than 1/4 wavelength at the lowest design frequency.

Abstract: A radar reflecting target comprises a plurality of reflecting elements spread along at least one linear physical dimension of the target, the elements being differingly spaced in the direction normal to said dimension so that respective retro-reflections by the elements of radio frequency energy from a remote soucre on a line of sight at an angle to said dimension, have differing phases and tend to cancel each other out. The invetion may be applied to single or two dimensional surfaces on such vehicles as ships or aeroplanes.

Abstract: A bulk RF absorber and a method for constructing same. The absorber is composed of multiple sheets of a reticulated dielectric material, each sheet being coated with at least one layer of radiation absorbing material to create a radiation absorption gradient across a width dimension of the sheet. The sheets are stacked with their respective absorption gradients aligned to form the bulk absorber. In one embodiment, the coated sheets are constructed by lengthwise feeding the dielectric material through a sputtering region and interposing a partial mask between the sputtering material and the face of the dielectric material. The contour of an edge of the mask, the sputtering rate and feed rate determine the resulting absorption gradient of the coated dielectric material. In another embodiment, a dipping process is used to coat each sheet with radiation absorbing material.

Abstract: The present invention relates to an electromagnetically anechoic chamber for EMC (Electromagnetic Compatibility) tests of electronic devices. The floor, ceiling and side wall of the anechoic chamber have panels of electromagnetic wave absorber having many ferrite tiles, and shield members comprising double layered shield members of copper sheets and iron sheets for absorbing and reflecting the foreign electromagnetic wave.

Abstract: An aircraft structure for the minimization of microwave energy reflection from the aircraft back to a receiver. The provision of structural configurations and materials operate to reduce microwave energy reflection toward its source or another receiver located at a level below the aircraft and laterally or forward thereof.

Abstract: A bulk RF absorber and a method for constructing same. The absorber is composed of multiple sheets of a reticulated dielectric material, each sheet being coated with at least one layer of radiation absorbing material to create a radiation absorption gradient across a width dimension of the sheet. The sheets are stacked with their respective absorption gradients aligned to form the bulk absorber. In one embodiment, the coated sheets are constructed by lengthwise feeding the dielectric material through a sputtering region and interposing a partial mask between the sputtering material and the face of the dielectric material. The contour of an edge of the mask, the sputtering rate and feed rate determine the resulting absorption gradient of the coated dielectric material. In another embodiment, a dipping process is used to coat each sheet with radiation absorption material.

Abstract: In a facade construction of high-rise structures, a corresponding layer construction is provided for suppressing reflections of incident electromagnetic waves, particularly of radar waves. For this purpose, an electrical resistance layer which has a surface resistance in the range of 300 to 1200 .OMEGA. is arranged at a distance from a reflecting surface. The distance between the reflecting surface and the electrical resistance layer is approximately 1/4 of the wavelength in the propagation direction of incident electromagnetic waves to be suppressed.

Abstract: What is disclosed is a wave absorber comprising an electromagnetic wave absorbing framework having a plurality of cells arranged to define arbitrary shape of U-shaped hollow spaces adapted to the wavelength of the electromagnetic wave to be absorbed, which is prepared by introducing bubbles into an inorganic fluid material, followed by solidification, and an electromagnetic wave absorbing ferrite material applied at least on the walls of the cells defining said U-shaped hollow spaces; wherein the main body of the electromagnetic absorber may have on the surface a weathering-resistant electromagnetic wave transmitting panel comprising a composite of ceramic plate and a Kevlar cloth, glass cloth or other ground fabric or the same inorganic fluid material constituting the wave absorbing framework optionally containing a Kevlar fiber or glass fiber; said wave absorber may be formed to serve also as a building block.

Abstract: Absorber elements for reducing electromagnetic leakage radiation, in particular in the vicinity of horn antennas, are in the form of ribs with a roof- or wedge-shaped cross section arranged such that the angle enclosed by lateral surfaces of the absorber elements is less than 90.degree., so that at least the leakage radiation impinging in general parallel to the center plane of the absorber elements arrives at a large angle of incidence, i.e. glancingly. In particular, if the angle of incidence approximately corresponds to the Brewster angle, the result is an almost complete absorption of the corresponding polarization components of the leakage radiation. The absorption effect can be further optimized by proper selection of the configuration of the roof- or wedge-shaped absorber elements.

Abstract: Dielectric or magnetic anisotropy layers, laminated composite material incorporating said layers and their production process. The laminated material has at least two stacks of assembled layers, a first stack constituted by a layer (2) of first dielectric fibers (4) oriented parallel to a first direction (x), and a layer (6) of first magnetic fibers (8) oriented parallel to a second direction (y) perpendicular to the first direction (x), and a second stack constituted by a layer (10) of second dielectric fibers (12) oriented parallel to the second direction (y), and a layer (14) of second magnetic fibers oriented parallel to the first direction (x). Each fiber is constituted by a thermoplastic polymer sheath containing a pulverulent magnetic or dielectric charge.

Abstract: Disclosed is a wave absorber, comprising a wave absorbing panel prepared by forming a mixture containing a ferrite powder, a metal fiber, a molding material and a resin into a framework, by means of molding and/or press-cutting, having an arbitrary shape of hollow spaces which are adapted to the frequency and wavelength of an electromagnetic wave, and an electrically conductive filter plate, made of a mixture of a ferrite powder, a metal fiber and a resin, laminated thereon. The wave absorber may have a weathering-resistant electromagnetic wave transmitting plate on the surface thereof and the electromagnetic wave transmitting plate may comprise a reinforced ceramic panel made by laminating a ceramic plate with a Kevlar cloth, glass cloth or other web.