Abstract: Variational calculus principles are applied directly to the radiation integral to minimize the radar signature of a two- or three-dimensional geometry. In the preferred embodiment, the radiation integral is minimized through the solution to a differential equation generated by Euler's calculus of variations (CoV) equation. When used in conjunction with a minimizing sequence, the analysis affords a broad search of all possible coefficient values to ultimately arrive at global minima. Compared to existing techniques, the approach locates local extrema quickly and accurately using fewer impedance matrix calculations, and optimization using the invention is possible over a wide band of frequencies and angles. The method is applicable to a wide variety of situations, including the design of stealth platforms.

Abstract: A glue-gun applied hot-melt radar-absorbing material (RAM) and method of use thereof is provided. The hot-melt radar-absorbing material composition comprises: (a) 70 to 85 wt % carbonyl iron powder; (b) 2 to 10 wt % of a metal deactivator; and (c) balance a thermoplastic polyurethane. The method for repair of a body comprising a radar-absorbing material, comprises: (a) formulating the hot-melt radar-absorbing material of the present invention; (b) forming the hot-melt radar-absorbing material into a shape; (c) applying the hot-melt radar-absorbing material in a molten state onto the body; and (d) allowing the hot-melt radar-absorbing material to cool to room temperature. The shape of the hot-melt RAM is advantageously a “glue stick”, which is configured to go into a glue gun. The repair operator loads the glue stick into the glue gun and pulls the trigger. The glue gun heats the glue stick, and the molten material is applied to the area to be repaired.

Abstract: A ruggedized ultra high radio frequency antenna disposable at the rear of a hardened target penetrator warhead is provided. The antenna is usable for communicating signals from a transmitter in a deployed target penetrator warhead to a local repeater where retransmission to a more remote location can occur. The antenna includes a length-shortening and penetration abuse-resistant dielectric embedding material also supporting the subterranean signal communication to the local repeater function. Antenna radiating element fabrication from porous material such as screen wire and use of the dielectric material in a manner providing large G force tolerance and external dielectric variations are included.

Abstract: A winged bomb is launched from a launch aircraft and glides to a target. During the glide the winged bomb follows a calculated guide path stored in a on board computer, with correction generated by the computer using data from an altimeter and global positioning receiver. Near the termination of the glide a television camera is activated and transmits signals to a remote location from which final correction are manually generated and transmitted by radio to the bomb. The bomb is designed with low radar cross section.

Abstract: An RF interface is configured as a laminate structure having a core layer of a ferromagnetic ceramic material, such as barium strontium titanate, whose permitivity is electrically controllable to modify the behavior of impinging electromagnetic energy, as one of minimally attenuated transmission, maximally attenuated absorption, and highly unattenuated reflection. Opposite surfaces of the ceramic core are coated with an electrically lossy material, such as indium tin oxide, to which a differential DC voltage is applied, and thereby imparting a DC electric field to the core layer. For an antenna application, during transmit/receive mode, the differential voltage has a magnitude that renders the laminate's core highly conductive, and thereby reflective to the RF wavelength being sourced from or received by an associated feed horn. During other times, the differential voltage renders the laminate effectively transparent to RF wavelengths in a prescribed band of interest (e.g.

Abstract: A transmission line electromagnetic reflection reduction treatment is disclosed herein. This invention relates to radar cross section reduction in vehicles including aircraft, submarines, warships, tanks, troop carriers, and mobile weapons, and reduction of electromagnetic (EM) interference from civil engineering structures including bridges, buildings, power lines, and antennas.

Abstract: A suppression system for a gas turbine engine uses a tapered exhaust manifold with a plurality of exhaust nozzles acting in conjunction with a plurality of mixing cells to produce cooling of an exhaust gas stream upon exit from an aircraft. The cooling air is supplied to the mixing cells in such a way that the walls of the cells are inherently maintained at a desired temperature without the use of dedicated cooling apparatus such as finned head exchangers, film cooling slots, etc. This approach allows the typically conflicting requirements of low IR signature and low radar cross section to be simultaneously satisfied in an efficient, light weight and low cost manner.

Abstract: In accordance with the present invention, there is provided a low observable aerodynamic control system for integrated use with an aircraft fuselage. The control system is provided with a shadow structure having an inner sloping region and an outer sloping region. The inner sloping region defines a shadow structure concavity. The outer sloping region is attachable to the aircraft fuselage. The control system is further provided with an aerodynamic control device having a body portion and a base portion. The base portion is disposed within the shadow structure concavity. The body portion extends from the base portion beyond the shadow structure concavity.

Abstract: An RF absorber system (26) for absorbing RF energy in the payload chamber (20) of a launch vehicle is disclosed. The RF absorber system (26) includes a plurality of panels (27) for providing acoustic absorption and for housing RF absorbing material. The panels (27) comprise a plurality of acoustic absorbing layers (30a, 30b, and 30c) and at least two RF energy absorbing sheets (36a and 36b) for absorbing RF energy, and an outer film layer (38) for dissipating static charges and acting as a contaminant barrier. The panels (27) have an outer surface (32) and an inner surface (34). The RF energy absorbing sheets (36a and 36b) are sandwiched between the plurality of acoustic absorbing layers (30a, 30b, and 30c), thus creating alternating acoustic absorbing layers and RF energy absorbing sheets. The outer film layer (38) is secured to the outer surface (32) of the panel (27).

Abstract: An electromagnetic wave absorber which is suitable for cellular phones, portable communication terminals and other portable electronic apparatus. The electromagnetic wave absorber is provided with a thin absorbing substrate formed of an electromagnetic wave absorbing material having a thickness of 0.01 .mu.m to 1.0 mm. Such a thin absorbing substrate is realized by making adjustment holes in the absorbing substrate and increasing a value of apparent magnetic permeability. Specifically, even in the absorbing substrate as thin as 0.8 mm, by making multiple adjustment holes, electromagnetic waves can be absorbed in a frequency ranging from 1.5 to 2.2 GHz.

Abstract: Novel devices for providing shielding from and absorption of broadband electromagnetic radiation, and methods of manufacturing and using these devices, are disclosed. The device is comprised of a perforated electrical absorbing layer, containing conductive polymers, laminated to a metal plate. Additional layers may be incorporated into the device including one or more additional layers of electrical absorbing layers, magnetic absorbing layers and impedance matching layers.

Abstract: A radio wave absorbent comprises an Ni--Cu--Zn base ferrite having a major composition comprising 49 to less than 50 mol % of Fe.sub.2 O.sub.3, 32 to 35 mol % of ZnO, 3 to 9 mol % of CuO and 9 to 14 mol % of NiO. The radio wave absorbent further contains an additive molybdenum oxide in an amount of greater than 0 to 0.10 wt %, calculated as MoO.sub.3, with the proviso that the total amount of the major composition is 100 wt %. The radio wave absorbent may be used as an exterior or interior material for a building or structure.

Abstract: An electromagnetic wave absorbing shielding material which is thin and lightweight and shows high electromagnetic wave absorbing capacity in a wide frequency region. The material comprises:(1) a one-dimensional conductive segment pattern which is a conductive segment pattern formed from a conductive material, wherein the conductive segment pattern has a length of more than 1/2 of the wavelength of the subjective electromagnetic wave, and the segment pattern has no electrical connection therebetween,(2) an electromagnetic wave shielding layer, and(3) an insulating intermediate material having a thickness of 0.1-10.0 mm, located between the one-dimensional conductive segment pattern (1) and the electromagnetic wave shielding layer (2).

Abstract: The microwave absorption performance of a fiber loaded thermoplastic syntactic material is improved by geometrically reshaping the surface into a waffle shape. Starting with a fiber loaded version of thermoplastic syntactic foam, the front face geometry is then modified. Typically, the angle and frequency response is a function of both the front face angle and the skin thickness. These effects are minimized in this concept by using a pyramidal surface in which the field enters the material normal to at least one surface at almost all incident angles. The attenuation is over 20 dB, from S through Ku bands, over a broad angle range of up to 75 degrees off normal. An added benefit is that this system has a rigidity that is suitable for many structural applications.

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: An apparatus for encapsulating a warhead or bomb for the purpose of reducing the weapon's radar cross-section, including a hollow jacket and a hollow tail section. The warhead is inserted into the specially-shaped jacket and into at least part of the tail section. The jacket is secured to the warhead by lugs and the tail section is secured to the jacket or to the warhead. The jacket has two pointed seams on opposite sides of a vertical plane passing through the warhead pointing outward from the vertical plane and which extend along the length of the jacket. The front of the tail section has a serrated edge which overlaps the rear end of the jacket. The tail section has horizontal fins and downward and outward extending fins. The lugs allow the apparatus to be releaseably attached to the bottom the fuselage or the bottom of a wing pylon of a military aircraft.

Abstract: A system for sealing an exposed area of a surface coated with a radiofrequency signal absorbing coating includes a heat-responsive compound that transforms from a solid state to viscous melted state at temperatures above a predetermined temperature and that returns to a solid state after cooling to temperatures below the predetermined temperature. The heat-responsive compound has a radiofrequency absorbing material for absorbing radiofrequency signals at approximately equal frequency to those that the radiofrequency signal absorbing coating absorbs. An applicator applies the heat-responsive compound in the viscous melted state to cover the exposed areas. An absorptive tape conceals any gap or fastener associated with the exposed area and absorbs radiofrequency signals having approximately equal frequencies to those of the radiofrequency signal absorptive coatings.

Abstract: A material for disposition on a surface comprising Fe, Co, or FeCo in the form of small single magnetic domain metallic clusters disposed in an insulating matrix of BN. The material may be utilized as a new absorbing material for radar microwave signals. Additionally, the material may be utilized on a magnetic storage substrate to form a new magnetic recording medium.

Abstract: An electronic attenuation and camouflage device comprising a novel cooling device comprised of microspheres; an additional set of microspheres containing radar attenuating materials <RAM> capable of absorbing certain frequencies; and an additional set of microspheres containing electro-reactive substances enabling color change of a structure to match background, all comprising structures or being placed in a matrix; a structure; a machined part; a coating; or a series of matrices, structures, parts or coatings, which combined structures enable concealment of an object.

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: A coating composition for the attenuation of the reflection electromagnetic radiation and particularly electromagnetic radiation have a wavelength of greater than 800 nm including the near infrared is described. The composition comprises a chromophore capable of absorbing up to about 95% of the electromagnetic radiation having a wavelength greater than 800 nm. Optionally, the composition may comprise microbeads that serve the purpose of also scattering the electromagnetic radiation.

Abstract: A method of construction to make military craft and weapons totally invisible to radar and active infra-red by the configuration of exterior surfaces, each surface having that specific surface figure which causes the reflected electromagnetic emission to be convergent to a point, and to be as small a return beam as possible at the distance of the detection device from the craft using the invention.

Abstract: A radar shield, in particular for an aircraft radar antenna, comprises a plurality of elongate triangular blinds 6 that may be stowed on individual rollers 7. To deploy the shield, the blinds are drawn from the rollers by wind-up spools to form a pyramidal shield within, for example, the aircraft radome assembly.

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 composition is disclosed for forming an EMI shielding gasket for instalion against a metal object, such as an aluminum frame member of an aircraft, wherein the composition is comprised of a mixture of a prepolymer composition of a flexible polyurethane material, a sacrificial metallic material which provides electrical conductivity and anodic protection against corrosion of the metal object, and a curing agent for curing the prepolymer composition. The sacrificial metallic material can be a metal salt selected from the group consisting of water soluble zinc and cadmium salts. Water can also be present to serve two functions, as a curing agent for the polyurethane and as a foaming agent, producing carbon dioxide. A method is also providing for installing an EMI shielding gasket on an aircraft between a graphite skin panel and a metal frame member. The composition for forming the EMI shielding gasket on a metal surface can also include an agent that cleans the metal surface to which the gasket is applied.

Abstract: An inflatable shield for suppressing the characteristic radiation signature of a satellite is described. The shield is conical-shaped and made from a thin synthetic polymer film material coated with a radiation reflecting material, such as gold or aluminum. At least one subliming agent is contained within the shield to inflate the shield when exposed to heat. An ultraviolet curable slurry coats the inner walls of the shield and permanently hardens the shield upon exposure to ultraviolet radiation from a self-contained source. The shield optionally may include absorbing and desiccant agents to absorb unwanted gas and water and prevent interference with the primary mission of the satellite. Additional means may be included for moving and positioning the shield with respect to the satellite.

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: A layered microwave radiation absorber comprises an absorbing layer bound to one side of a conductive layer (such as a metallic plate or foil), and an adhesive layer bound on the other side of the conductive layer. The combination may be applied directly to the surface of any object, but especially to an existing conductive object coated with an nonconductive coating (such as paint) without removing the nonconductive coating from the surface. Several types of absorbing materials may be used, and other layers may be included. The absorber has superior resistance to delamination.

Abstract: A vehicle in free space or air, with external surfaces primarily fashioned from planar facets. The planar facets or panels are angularly positioned to reduce scattered energy in the direction of the receiver. In particular, radar signals which strike the vehicle are primarily reflected at an angle away from the search radar or are returned to the receiver with large variations of amplitude over small vehicle attitude changes.

Abstract: A missile radome (1) has an acutely pointed profile and includes an antenna array of four elements (A, B) toe'd out around the boresight (5) for an amplitude comparison system. Certain received signals strike the antenna elements (A & B) after grazing the internal radome surface, and after single multiple reflections. The tracking characteristic consequently suffers perturbations. A layer (6) of surface wave absorbent material is provided on the inside of the radome (1) in combination with a mass of radar absorbent material (7) enclosed by this layer. The combination considerably improves the position.

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: 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: A system for installing a plastisol or similar compound into the interior ace of a spent squib-activated countermeasures cartridge. When the squib ignites and expels the countermeasures payload, the heat of combustion causes the plastisol to soften, react and expand to fill the empty container remaining after payload ejection. The foam filled container then acts as a radar absorber instead of a radar reflector and thus counters dispenser observability to RF energy.

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: 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: 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: The fiber composite for bearing structures for absorption of electromagnetic waves consists in its structure of at least three layers (2, 3, 4, 5, 6, 7, 8, 9) to be different in their electromagnetic material constants, whereby one or more fiber layers (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 23, 24) are used for the layers (2 to 9). The fiber layers demonstrate alternately by layers a high or low electrical conductivity such that the electromagnetic material constants of the layers (2 to 9) composed of the fiber layers (13 to 21 and 23, 24) and binder and the layer thicknesses are matched to one another such that the reflection attenuation is integrally maximized in a given frequency range.

Abstract: Microwave absorption in a varying magnetic field is investigated near electron cyclotron resonance with a network analyzer which is capable of swept frequency measurements, and of measuring reflection and transmission coefficients from 0.045 to 18 GHz, with greater than 80 dB dynamic range. The experimental conditions are such that the plasma is generated in a modified Penning discharge in a magnetic mirror configuration. A microwave beam is caused to propagate along the axis of the magnetic mirror field in the plasma column. The microwave beam is attenuated near the electron cyclotron resonance frequency, providing microwave absorption over a range of frequencies spanning the electron cyclotron frequencies present in the axially varying magnetic field. The attenuation, along with hot-plasma effects, are measured as a function of frequency by the network analyzer.

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: The present invention relates to fiber structures and methods for obtaining tuned response to high frequency electromagnetic radiation, particularly at microwave frequencies. In one embodiment, a woven fabric is prepared with ferrite filled fibers oriented perpendicular to dielectric filled fibers. The fill of the fibers is selected to reflect radiation having a known frequency and polarization. In other embodiments, tuned structures are provided by disposing sheets containing oriented ferrite and dielectric fibers parallel to one another and moving the layers relative to one another to achieve the desired impedance for incident radiation.

Abstract: High magnetic permeability composites are obtained by incorporating ferrite fibers in the composites. The ferrite fibers consist of a polymer and particulate ferrite fill at a concentration above the percolation threshold for the ferrite fill in the polymer (typically greater than 30 volume percent). The aspect ratio and ferrite concentration of the fibers are selected to minimize demagnetization fields in the fibers. The fibers can be dispersed in low concentration in an unoriented fashion in the composites to impart high magnetic permeability to the composite. In other embodiments, the fibers are oriented in the composites to impart high magnetic permeability to the composite for incident radiation of a particular linear polarization.

Abstract: A holographic aircraft antenna and method of fabricating the antenna are disclosed herein. The antenna includes a thin layer of dielectric strips of material contoured to and mounted on the conductive skin of the aircraft or a plurality of thin metal conducting strips secured to the skin of a composite aircraft. The spacing, width and size of the thin strips forms a hologram which is determined by the interference pattern of radio frequency beams selected for and directed at a holographic recording medium at particular angles to provide a desired or series of desired radiation patterns. In addition, a radar reduction device is provided wherein the hologram includes thin strips of dielectric material on the conductive skin of the aircraft or thin metal conducting strips on the composite aircraft.

Abstract: A decoy missile having the shape of a reentry vehicle and containing a pair of conically shaped dipole jacks in tandem, the jacks are shaped and spaced to provide a desired reflective cross section at a specific frequency, the rear cover plate of the decoy is constructed of radar absorbing material to aid in the enhancement process.

Abstract: The present invention is a method for making radar chaff consisting of metal rings having varying diameters, using photolithographic processes. One aspect of the invention has the steps of: providing a metal foil having a thickness suitable for use in radar chaff; overcoating the metal foil with a photoresist, to form a layered structure; undercoating the metal foil with a removable backing; exposing the photoresist to a quantity of actinic radiation for chemically modifying the photoresist into a photoproduct suitable for subsequent development, where the actinic radiation is patterned into a series of concentric rings; developing the photoresist, to expose the underlying metal in a series of concentric rings; removing the exposed metal to form a series of concentric metal rings on the removable backing; and removing the removable backing. Another aspect of the invention is a metal chaff precursor, comprising: a removable backing, coated with a plurality of concentric metal foil rings.

Abstract: A vehicle in free space or air, with external surfaces primarily fashioned from planar facets. The planar facets or panels are angularly positioned to reduce scattered energy in the direction of the receiver. In particular, radar signals which strike the vehicle are primarily reflected at an angle away from the search radar or are returned to the receiver with large variations of amplitude over small vehicle attitude changes.