Abstract: An electromagnetic wave absorber is formed by injection-molding a thermoplastic resin blended with approximately 20-60% by volume of soft magnetic material powder, and blended with a molding assistant and a kneading assistant. The electromagnetic wave absorber includes a unit cell having a bore extending from a top face to a bottom face. A portion of the bore located more adjacently to the bottom face than to the top face has a smaller cross-sectional area than the bore at the top face, and a height of the unit cell from the bottom face to the top face is approximately at least 1.2 times and approximately at most 10 times as large as the maximum width of the bore at the top face of the unit cell.

Abstract: A radar-absorbing panel (9) includes a honeycomb core (11) and a lower skin (13), where the lower skin (13) is attached to the bottom of the honeycomb core (11). The honeycomb core (11) is made up of individual cells (15), which may be filled with aerogel. The individual cells (15) are approximately ½ of an inch in size with polygonal shape.

Abstract: The invention relates to an electromagnetic radiation absorber for a preselected frequency range, comprising: an absorbent sheet (10) located such that said electromagnetic radiation falls on it, and a conductive base (20) located under said absorbent sheet, wherein said absorbent sheet: has a total thickness e exceeding ?/(?)1/24, where ? is the wavelength of the incident electromagnetic radiation, and is made up of a dielectric material containing amorphous magnetic microwires, the magnetic permeability of which in the preselected frequency range has an imaginary part ?? which is at least 100 times greater than the corresponding real part ??, said microwires being distributed in a volume having a thickness e2 of at least ?/(?)1/216, where ? is the dielectric constant of the absorbent sheet and said volume is located a distance e3 from the conductive base that is not less than ?/(?)1/28.

Abstract: The panes (1) of a naval vessel or military vehicle are often coated with a radar-reflecting layer (20) for reduction of the radar signature of the vessel/vehicle. At the same time this layer increases an enemy's possibility of recognizing the vessel in passive IR reconnaissance since the layer increases the reflectance also for IR radiation to a considerable extent. As a result, the intensity of IR radiation that an enemy receives from the panes is much lower than that from the rest of the vessel, which with signal processing can be used to increase the possibility of recognizing the vessel. According to the invention, it is suggested that the panes (1) on the outer face (8) also have a second layer (21, 22) to increase emittance especially within the IR range 2-20 ?m which is normally used for reconnaissance and the like. This second layer (21, 22) comprises especially two coatings, one of which is active in the IR range 3-5 ?m and the second in the IR range 7-14 ?m.

Abstract: A one-way reflective sensor shield with an increased bandwidth meta-materials coating is provided which substantially reduces or eliminates deleterious electronic signatures and backscattering. The one-way reflective sensor shield with meta-materials coating operates according to surface plasmonic coupling phenomena and achieves a mirror-like one-way reflection of electromagnetic signals. In this arrangement, the meta-materials coating is composed of a dielectric material, and the corrugated metal strips are composed of a metallic conductive material with a negative dielectric constant, to allow surface plasmonic coupling between the plasma in the metal and the incident electromagnetic field. Surface plasmons occur at the interface of a material with a positive dielectric constant, such as dielectric surface, with that of a negative dielectric constant, usually a metal or doped dielectric, such as the metal strips. Sensor devices and sensor shielding systems are also provided.

Abstract: The purpose of the present invention is to provide an easy-to-manufacture electromagnetic wave absorption material usable from submillimeter wave region to millimeter wave region with an excellent radio wave absorbing performance and a variety of usage thereof. The present invention is characterized by an electromagnetic wave absorption material comprised of a dispersions of at least one of the materials: a multi-layer hollow globule of carbon, a schungite carbon, and the schungite ore; mixed into a matter having a high electrical resistivity. The invention is further characterized by an electronic device, an optical transmission module, an optical reception module, a high frequency telecommunication equipment, and a stop-free automated tollgate system, wherein at least a part of their board, electronic element, and circuit wiring are covered with said electromagnetic wave absorption material.

Abstract: An electromagnetic wave absorber for use in the high frequency range above 1 Ghz and a composite member are characterized by the fact that magnetic metal grains are covered with ceramic above 20 volume %. Further, a method of manufacturing the electromagnetic absorber and the composite member is characterized by the fact that composite magnetic particles, in which a plurality of magnetic metal grains and ceramic are unified, are formed through a mechanical alloying method applied to a composite powder composed of magnetic metal powder and ceramic powder. The electromagnetic wave absorber can be used in a semiconductor device, an optical sending module, an optical receiving module, an optical sending and receiving module, an automatic tollgate in which erroneous operation due to electromagnetic wave disturbance is provided by use of the electromagnetic wave absorber.

Abstract: An apparatus for adaptive camouflage with independent control of both temperature and apparent color. The apparatus has cells or individual pixels behind a transparent outer layer. The temperature of the outer layer is controlled by a heat transfer fluid flowing in a closed circuit in each cell, the fluid being cooled or heated by Pelletier elements located behind the assembly. Color changes can be activated separately at the back of the transparent layer by the rotation of metallic triangles whose sides are covered with various color paints, the triangles being located behind the transparent layer. Radar absorption is obtained by the transparent layer and heat transfer fluid and by the selective orientation of the metallic triangles in various directions. The apparent signature of the assembly can then be varied by adapting the signature of the various cells to current environmental conditions when background conditions alter.

Abstract: A method for reducing radar cross section of an object that has conductive portions and that is expected to be scanned by radar, which includes providing the object with a multiple layer radar cross section reducing structure that reduces or entraps or dissipates radar waves therein so that the size or configuration of the object cannot be correctly detected by radar scanning. The invention also relates to the radar cross section reducing structure alone or associated with an object such as a vehicle that transports personnel or equipment. The structure can be provided on an object that previously has no stealth capability or it can be applied to an object that already has stealth capability for increasing its capability to prevent correct detection by radar scanning.

Abstract: The invention describes a HF-reducing green roof. This green roof comprises a support construction consisting of a layer of textile fibers and/or a substrate (12), a vegetation layer (14) of low plants, and a flat or three-dimensional structure of electrically conductive filaments. This structure supplements the support construction or forms part thereof. The intermediate spaces between adjacent electrically conductive filaments (10) are smaller than one quarter of the wavelength of the electromagnetic HF-radiation to be shielded.

Abstract: An anechoic chamber (100) is provided with a system for introducing wireless communication signals into the anechoic chamber (100) for establishing wireless signaling with equipment under test (122), without interfering with signals from the equipment under test (122) that are to be measured in the anechoic chamber (100). The system comprises a low reflection cross-section cable (236) that extends through the chamber (100) to a weakly radiating small antenna (242, 502) that is positioned proximate the equipment under test (122).

Abstract: Electromagnetic energy absorbing devices are formed of a conductive loaded resin-based material. The conductive loaded resin-based material comprises micron conductive powder(s), conductive fiber(s), or a combination of conductive powder and conductive fibers in a base resin host. The ratio of the weight of the conductive powder(s), conductive fiber(s), or a combination of conductive powder and conductive fibers to the weight of the base resin host is between about 0.20 and 0.40. The micron conductive powders are formed from non-metals, such as carbon, graphite, that may also be metallic plated, or the like, or from metals such as stainless steel, nickel, copper, silver, that may also be metallic plated, or the like, or from a combination of non-metal, plated, or in combination with, metal powders. The micron conductor fibers preferably are of nickel plated carbon fiber, stainless steel fiber, copper fiber, silver fiber, or the like.

Abstract: A millimeter-wave radar has a radome or radar cover including a layer, the dielectric constant of which is a greater than that of the other portion without the layer, or including a magnetic loss layer in an appropriate position with respect to the antenna. The dielectric constant of the radome or radar cover can be made higher in a portion corresponding to the side of the antenna than in a portion corresponding to the front of the antenna.

Abstract: An electromagnetic wave absorber having an excellent electromagnetic wave absorption characteristic in 5 to 6 GHz band. The electromagnetic wave absorber has a matrix and powder filled in the matrix. The particles of the powder have electrical conductivity at least in surface regions thereof and have a particle diameter of 3 to 20 ?m as expressed by D50 value. A volumetric ratio (V) in which the powder is filled in the matrix is set such that a standardized value expressed as a value obtained by dividing a complex relative permeability (??) of the electromagnetic wave absorber in a frequency band to be absorbed thereby by the volumetric ratio (V) is constant as far as the particle diameter of the powder used, as expressed by the D50 value, is within the range of 3 to 20 ?m.

Abstract: A radio frequency anechoic test chamber (100) includes a test stand (118) that includes a relatively small diameter, mechanically robust, telescoping lower vertical support column (202), a large diameter thin walled middle vertical support column (204) that includes a sheet or coating of absorbing material (224) disposed proximate the circumference of the thin walled middle support column, (204) and an upper support member (206). The radio frequency anechoic test chamber provides improved ripple performance that allows more accurate measurements of the gain pattern of radio frequency equipment.

Abstract: Described herein is a method and system for providing a countermeasure against laser detection systems using nanocomponent material that is tailored to cloak or obscure a target from detection by transmitted laser radiation. The nanodot material absorbs and/or down-converts the transmitted laser radiation. Similarly, described herein is a method and system for providing a countermeasure against laser systems intended to blind a target through the use of a specifically engineered nanocomponent material for absorbing and/or down-converting the radiation from the laser system.

Abstract: System and method for improving the interference resistance of an radio frequency (RF) antenna system through passive prescreening of the RF energy incident upon the antenna. The invention physically partitions the RF environment into two or more sectors with respect to the direction of arrival of incident energy. The power level of the RF frequencies of interest incident upon each sector is determined such that whenever the power level exceeds a given threshold, the received signal from energy incident on that sector is modified.

Abstract: Disclosed is a device for eliminating electromagnetic waves which consists essentially of an electromagnetic-wave trapping means comprising mainly a coil, and a discharge means made on the opposite end to the basement of the trapping means, wherein the coil having a diameter which gradually decreases from the basement to the opposite end of the trapping means.

Abstract: An electromagnetic wave absorber comprises an electromagnetic wave absorber molded element, plate-shaped sintered ferrite, and a metal plate. The molded element incorporates a tile-shaped base portion and a wedge-shaped apex portion disposed on the base portion. The molded element is formed by injecting slurry into a mold, the slurry being obtained through mixing a molding material for the wave absorber with water, and curing the slurry. The molding material includes a magnetic material, an inorganic fiber and an inorganic binder. When these ingredients are mixed with water, the molding material first exhibits fluidity and then a curing reaction in a temperature range of 1 to 40° C.

Abstract: There is provided a radar system for protecting a radar compartment from a transmitted radar beam. The radar system comprises an antenna having a transmitter surface for transmitting the radar beam. There is further provided a protective member having an outer protective surface. This protective member is externally located adjacent the antenna for protecting the radar compartment from the transmitted radar beam. In addition, an alignment member is disposed between the antenna and the protective member. The alignment member is sized and configured to align the transmitter surface towards the outer protective surface for guiding the transmission of the radar beam therethrough. By featuring these components in such an arrangement, an operating frequency of any portion of the transmitted radar beam which diffracts from the outer protective surface can be mitigated to protect the radar compartment therefrom.

Abstract: The present invention is a multi-piece barrel shroud which provides IR signature and radar backscatter reduction over the entire length of the barrel by utilization of special radar absorbing materials and shaped in accordance with commonly known radar signature reduction techniques. The interior of the shroud includes cooling passages for the circulation of ambient air by way of a forced air circulation system which provides IR reduction. To facilitate barrel movement while minimizing weight, the majority of the shroud is stationary and is independent of the gun barrel. At least one other piece of the shroud is attached to the barrel near the muzzle end and designed to move in unison with the muzzle during recoil. The recoiling portion of the shroud is sized to mate with an annular recess within the distal end of the stationary portion so as to provide continuous shielding of the barrel throughout the entire range of recoil displacement.

Abstract: A rapidly deployable camouflage device for concealing recognizable signatures of military objects, comprising a camouflage balloon (1) and a deployment and undeployment device, the latter being equipped with a housing (2) and a fan (3) for inflating the balloon (1) arranged on an opening (4) in the housing. According to the invention, the balloon can be pulled into the housing by means of pull lines (7) secured at one end to the inside of the balloon opposite the opening (4), and at the other end to a motor-driven winding device inside the housing (2). The balloon is thus pulled in in such a way that it is reversed inside the housing, from which state if can then be blown out unreversed as rapidly deployable camouflage.

Abstract: A radio wave absorber is provided which can be produced at a low cost compared to the case of using silicon carbide fiber and which is also superior in radio wave absorption property in 76 GHz band (75-77 GHz frequency band). The radio wave absorber is produced by arranging a radio wave absorbing layer onto the surface of a metal body. The radio wave absorbing layer is made of a radio wave absorbing material containing silicon carbide powder dispersed in matrix resin. Average particle diameter of the silicon carbide powder is 4-40 ?m. Silicon carbide powder content in the radio wave absorbing material is 15-45 volume %. Thickness of the radio wave absorbing layer is adjusted so that reflection attenuation of not less than 10 dB is provided in 76 GHz band.

Abstract: The invention is a protective cover assembly having at least one part for a surface of a structure. In detail, the invention includes a first flexible layer of heat resistant material bonded to the structure having an outer surface with a radar cross-section reducing shape. A second layer of radar signature reducing material is bonded to outer surface of the first flexible layer and includes 1) a film of conductive material bonded to the first flexible layer; and 2) a film of radar absorbing material bonded to the film of conductive material. A third layer of heat resistant material is bonded to the second layer, the third layer made of a dielectric material having a thickness selected to provide a reduction in the radar cross-section of the cover when combined with the film of radar absorbing material.

Abstract: An electromagnetic wave absorber comprising a soft magnetic material powder and a binding material, wherein the composition of the flat powder of the soft magnetic material is Ni-30-60% Fe, is provided, and the electromagnetic wave absorber is thinner than conventional ones, has a high absorption performance for electromagnetic waves of 1 to 3 GHz.

Abstract: There is provided a radar system for protecting a radar compartment from a transmitted radar beam. The radar system comprises an antenna having a transmitter surface for transmitting the radar beam. There is further provided a protective member having an outer protective surface. This protective member is externally located adjacent the antenna for protecting the radar compartment from the transmitted radar beam. In addition, an alignment member is disposed between the antenna and the protective member. The alignment member is sized and configured to align the transmitter surface towards the outer protective surface for guiding the transmission of the radar beam therethrough. By featuring these components in such an arrangement, an operating frequency of any portion of the transmitted radar beam which diffracts from the outer protective surface can be mitigated to protect the radar compartment therefrom.

Abstract: The invention is a protective cover assembly having at least one part for a surface of a structure. In detail, the invention includes a first flexible layer of heat resistant material bonded to the structure having an outer surface with a radar cross-section reducing shape. A second layer of radar signature reducing material is bonded to outer surface of the first flexible layer and includes 1) a film of conductive material bonded to the first flexible layer; and 2) a film of radar absorbing material bonded to the film of conductive material. A third layer of heat resistant material is bonded to the second layer, the third layer made of a dielectric material having a thickness selected to provide a reduction in the radar cross-section of the cover when combined with the film of radar absorbing material.

Abstract: A millimeter-wave radar has a radome or radar cover including a layer, the dielectric constant of which is a greater than that of the other portion without the layer, or including a magnetic loss layer in an appropriate position with respect to the antenna. The dielectric constant of the radome or radar cover can be made higher in a portion corresponding to the side of the antenna than in a portion corresponding to the front of the antenna.

Abstract: An electromagnetic wave absorber is formed of an Mn—Zn ferrite including: a spinel primary phase which contains 40.0 to 49.9 mol % Fe2O3, 4.0 to 26.5 mol % ZnO, 0.1 to 4.0 mol % TiO2 and/or SnO2, and the remainder consisting of MnO; and a secondary phase which contains CaO as a base component. In the ferrite, the mass of the spinel primary phase accounts for 50.0 to 99.0% of the aggregate mass of the spinel primary phase and the secondary phase.

Abstract: Structured pre-form bodies as panel lining for wide-band sound absorption are made of an open-cell foam material having a rigid framework co-vibrating in a resonant manner at low frequencies. The pre-form bodies have a base layer and a columnar structure positioned directly in front of or on the base layer. The columnar structure has a non-symmetrical distribution of height and cross-section, thereby forming a wide-band tuned moderator gap and the columnar height corresponds approximately to the density of the base layer. The columnar structure has a framework resonance adjustable as a function of parameters of the base layer.

Abstract: The invention relates to a device for exhausting hot gases with a reduced signature, for instance exhaust gases from an exhaust (7, 8) of a tank. The device is of the type comprising a means for mixing (9, 33) of the hot gases with fresh air from the exterior of the tank. To prevent the exhaust from, for instance, reflecting radar radiation and emit IR radiation, the device is provided with a protecting means (10, 34) which is positioned outside at least parts of said means. The device may comprise a space (12, 32) which accommodates preferably the entire means for mixing. The space is defined on the one hand by a shell (11, 31) towards the other spaces of the tank and, on the other hand, by the protecting means towards the exterior. The protecting means has openings (23, 25) for passing preferably a gas mixture from the means to the exterior and fresh air from the exterior to said means.

Abstract: The present invention provides a flame-retardant electromagnetic wave absorber that exhibits excellent formability and electromagnetic wave-absorbing properties, and can be easily assembled and constructed. The electromagnetic wave absorber comprises a wave-absorbing body and a base plate supporting the bottom thereof, wherein the wave-absorbing body is formed in a pyramid shape by fitting polygonal wave-absorbing plates into each other.

Abstract: A radio wave absorber unit includes two or more molded bodies in a pyramid or wedge shape whose radius at the tip end is from 0.5 mm to 7.5 mm and a base. A radius at the trough between adjacent molded bodies is 7.5 mm or less. A unit including molded bodies and the base is integrally formed from propylene-based conductive expanded beads. The bases of adjacent units are connected by fitting their recessed and raised portions to each other. The expanded bead size is in the range from 2 mm to 10 mm, and beads with two or more different bead diameters can be used. A hollow molded body can be formed by providing a hollow structure inside.

Abstract: A method of absorbing microwave radiation is provided. The method comprises placing a structure in the path of the microwave radiation, the structure comprising an array of metal plates supported over a metal substrate by vertical conducting vias. The structure finds specific use in missiles having a dome portion that operates in a stealth mode. At least the inside of the dome portion is provided with the above-described structure for absorbing microwave radiation. The structure also finds use in anechoic chambers for use in testing microwave-emitting devices. Such anechoic chambers have walls, a floor, and a ceiling, which are provided with the above-described structure for absorbing microwave radiation. Surface patterning is thus used to enhance the micro-wave absorption. In addition, the frequency over which the material is highly absorptive can be shifted by changing the height of the structure, thus allowing active control (“tunable in real time”).

Abstract: An electromagnetic wave absorber including: a porous substrate having a large number of pores piercing the porous substrate; and an absorbent film formed on circumferential surfaces of the pores and constituted by a mixture of an electromagnetic wave absorbing filler and an electromagnetic wave absorving high-molecular material, wherein the pores are not blocked with the absorbent film so that the pores are permeable to gas. Accordingly, the electromagnetic wave absorber is high in electromagnetic wave absorbing performance, can be made thin and lightweight and is so excellent in reliability that the electromagnetic wave absorbing performance can be offered over a very broad range.

Abstract: The present invention is a multi-piece barrel shroud which provides IR signature and radar backscatter reduction over the entire length of the barrel by utilization of special radar absorbing materials and shaped in accordance with commonly known radar signature reduction techniques. The interior of the shroud includes cooling passages for the circulation of ambient air by way of a forced air circulation system which provides IR reduction. To facilitate barrel movement while minimizing weight, the majority of the shroud is stationary and is independent of the gun barrel. At least one other piece of the shroud is attached to the barrel near the muzzle end and designed to move in unison with the muzzle during recoil. The recoiling portion of the shroud is sized to mate with an annular recess within the distal end of the stationary portion so as to provide continuous shielding of the barrel throughout the entire range of recoil displacement.

Abstract: A composite dielectric in which particles having a volume resistivity of between 2 ohms-cm and 2 mega-ohms-cm are dispersed. This composite dielectric is much more dissipative for electromagnetic fields in the microwave-frequency region than a conventional one wherein highly-conductive particles are dispersed.

Abstract: An electromagnetic wave absorber including: a porous substrate having a large number of pores piercing the porous substrate; and an absorbent film formed on circumferential surfaces of the pores and constituted by a mixture of an electromagnetic wave absorbing filler and an electromagnetic wave absorbing high-molecular material, wherein the pores are not blocked with the absorbent film so that the pores are permeable to gas. Accordingly, the electromagnetic wave absorber is high in electromagnetic wave absorbing performance, can be made thin and lightweight and is so excellent in reliability that the electromagnetic wave absorbing performance can be offered over a very broad range.

Abstract: A matching network hybrid electro-magnetic compatibility (EMC) absorber. A substrate of any number of materials serves as the frame on which partial coatings are placed. Design parameters governing the substrate and other parameters governing the coating control the electrical properties of the matching network hybrid EMC absorber. By performing partial and/or full coating, the physical shape and mechanical properties of the matching network hybrid EMC absorber may be de-coupled from the electrical properties. A designer modifies and controls the electrical performance of an electro-magnetic test system by special-tailoring a matching network hybrid EMC absorber. An electro-magnetic wave to ensure that a majority of the electro-magnetic wave is absorbed into a lossy, absorber material mounted on the walls of a test chamber in the frequency range from 20-500 MHz.

Abstract: A matching network hybrid electro-magnetic compatibility (EMC) absorber. A substrate of any number of materials serves as the frame on which partial coatings are placed. Design parameters governing the substrate and other parameters governing the coating control the electrical properties of the matching network hybrid EMC absorber. By performing partial and/or full coating, the physical shape and mechanical properties of the matching network hybrid EMC absorber may be de-coupled from the electrical properties. A designer modifies and controls the electrical performance of an electro-magnetic test system by special-tailoring a matching network hybrid EMC absorber. An electro-magnetic wave to ensure that a majority of the electro-magnetic wave is absorbed into a lossy, absorber material mounted on the walls of a test chamber in the frequency range from 20-500 MHz.

Abstract: An electromagnetic wave absorber comprising a soft magnetic material powder and a binding material, wherein the composition of the flat powder of the soft magnetic material is Ni-30-60% Fe, is provided, and the electromagnetic wave absorber is thinner than conventional ones, has a high absorption performance for electromagnetic waves of 1 to 3 GHz.

Abstract: A method of minimizing reflectivity of an electromagnetic absorbing structure within a prescribed frequency range, including at least one skin layer having a thickness, at least one spacer layer having a thickness, and at least one resistivity sheet having a resistivity. Then, the thicknesses of the at least one skin layer, the at least one spacer layer, and the at least one resistivity sheet are determined.

Abstract: A magnetic material exhibiting a high permeability at a high frequency range is materialized and a radio wave absorber exhibiting an excellent radio wave absorbing property by using such magnetic material is provided. The radio wave absorber comprises a mixed material containing a magnetic material grain, a resin material and a ceramic material or a low-melting-point metal material, in which the magnetic material grain is made into a disc shape is provided.

Abstract: An aircraft gas turbine engine is provided with low observable fan features which reduce the radar signature of the engine and its aircraft. An aircraft gas turbine engine fan section has in direct serial flow relationship an inlet having fixed high swirl angle inlet guide vanes, a first stage of first fan rotor blades, a stage of first variable angle stator vanes, and a fan bleed. The inlet guide vanes are angled to block the linear line of sight of the rotating fan blades through the inlet and include a RAM treatment which preferably is a coating of a radar absorbing material on the surface of the inlet guide vanes. The exemplary embodiment has a multi-stage fan section with the mid-stage fan bleed disposed between the first and second stages of fan rotor blades.

Abstract: A radiation absorber comprising a substrate having free charges capable of being driven to form resonance charge density oscillators and a dielectric layer coated onto said surface wherein the dielectric layer has a textured/patterned surface. The substrate is preferably metallic and the dielectric layer is waveform.

Abstract: A radio wave absorber-assembling member comprises an incombustible base material enabled to assemble a desired-shape structure, and radio wave-absorbent incombustible materials fixed to predetermined regions of the base material. The base material is folded at regions to which no incombustible material is fixed. Then, end portions of the base material are bonded to each other so that a radio wave absorber is obtained.

Abstract: A radio wave absorber having a good radio wave absorption characteristic and high impact resistance is provided which is less susceptible to damages by chipping or the like during the manufacture or in use. The radio wave absorber unit includes two or more molded bodies in a pyramid or wedge shape whose radius at the tip end is from 0.5 mm to 7.5 mm and a base. A radius at the trough between adjacent molded bodies is 7.5 mm or less. A unit including molded bodies and the base is integrally formed from propylene-based conductive expanded beads. The bases of adjacent units are connected by fitting their recessed and raised portions to each other. The expanded bead size is in the range from 2 mm to 10 mm, and beads with two or more different bead diameters can be used. A hollow molded body can be formed by providing a hollow structure inside.

Abstract: The present invention provides a broadband RF absorptive structure based on a classic Salisbury screen. Closely-spaced frequency selective surface reflective layers interact with a ground plane to reflect coherent signals at 377&OHgr; into a spacecloth front layer. The frequency response of the absorptive structure is relatively flat across an octave (i.e. a 2:1 frequency ratio) bandwidth. The overall thickness of the inventive structure is less than &lgr;/4 thickness of the interactions of the FSS layers and the ground plane.

Abstract: A device to conceal a radar or any other system for the transmission and reception of electromagnetic waves represents, for example, a pattern in relief. The device comprises at least one front part transparent to electromagnetic and optical waves, one rear part transparent to electromagnetic waves facing transmission and/or reception means and a form representing the manufacturer's logo placed between the parts. This form has an cellular structure with RF characteristics close to those of air. That device can be applied especially in radars equipping vehicles.

Abstract: According to the invention, there is provided a device enveloping said superstructure and able to reflect electromagnetic waves, said device comprising a truncated pyramidal frame (6) and a net (7) covering the small base of said frame (6).