Abstract: A ceramic filled fluoropolymer-based electrical substrate material well suited for forming rigid printed wiring board substrate materials and integrated circuit chip carriers is presented which exhibits improved electrical performance over other printed wiring board materials and circuit chip carriers. Also, the low coefficients of thermal expansion and compliant nature of this electrical substrate material results in improved surface mount reliability and plated through-hole reliability. The electrical substrate material preferably comprises polytetrafluoroethylene filled with silica along with a small amount of microfiberglass. In an important feature of this invention, the ceramic filler (silica) is coated with a silane coating material which renders the surface of the ceramic hydrophobic and provides improved tensile strength, peel strength and dimensional stability.

Abstract: A surface wave microwave antenna is presented in which transmission or reception of microwave energy is effected by discontinuities in a dielectric body positioned between a central feeder element and a ground plane. When used as a transmitter, the central disc propagates surface waves in the dielectric body in expanding circles; and the discontinuities in the dielectric body act as radiating or scattering sites to couple the waves to free space. When used as a receiver, the reverse will occur.

Abstract: A radome being a unitary structure comprised of a fiber reinforced plastic is produced with a large percentage of the fibers being randomly oriented in a plane parallel to the inner surface of the radome. The radome is produced by packing a layer of fiber filled powder around a mandrel having its outer contour resemble the inner contour of the radome. The mandrel and packed powder are then subjected to isostatic pressing to properly orient the fibers. The radome is finished by sintering the powder and removing the finished form from the mandrel.

Abstract: Unitary hollow structures, for example radomes, comprised of fiber reinforced plastic are produced with a large percentage of the fibers being randomly oriented in directions essentially parallel to the wall surfaces of the structures and with at least one surface having grooves to reduce microwave reflection. The structures are produced by packing a layer of fiber filled polymeric material in powder form around a mandrel which may have a pattern of grooves or ridges in its outer surface. The mandrel and packed powder are subjected to isostatic pressing to properly orient the fibers and achieve a density increase and powder cohesion. The pressed structure is sintered and the outer surface subsequently machined to a finished contour.

Abstract: A parallel plate waveguide microwave antenna is presented in which transmission or reception of microwave energy is effected by radiating waveguide slots or apertures in a metallized glass plate or plate of other rigid dielectric material. The metallized glass plate cooperates with another metallized glass plate or other rigid dielectric material or a metal plate to define a parallel plate waveguide with air or an inert gas or vacuum as the dielectric between the plates. When used as a transmitter antenna, a central electrode propagates waves in the dielectric medium in expanding circles; and the slots or apertures in the metal layer act as scattering sites to couple the waves to free space. When used as a receiver antenna, the reverse will occur.

Abstract: A microstrip antenna is presented in which the circuit pattern is on the inner side of a glass plate and is spaced from the ground plane by an air dielectric. The outer side of the glass plate serves as a protective cover for the circuit pattern and the ground plane.

Abstract: A method of producing unitary hollow structures, for example radomes, comprised of fiber reinforced plastic with a large percentage of the fibers being randomly oriented in directions essentially parallel to the wall surfaces of the structures and with at least one surface having grooves to reduce microwave reflection is presented. The structures are produced by packing a layer of fiber filled polymeric material in powder form around a mandrel which may have a pattern of grooves of ridges in its outer surface. The mandrel and packed powder are subjected to isostatic pressing to properly orient the fibers and achieve a density increase and powder cohesion. The pressed structure is sintered and the outer surface subesquently machined to a finished contour.

Abstract: A radome combines low dielectric constant and dissipation factor at microwave frequencies with mechanical strength and rigidity as well as resistance to ablation and rain erosion at hypersonic velocities in the range of Mach 4 to 6. Continuous filament glass fabric and/or strand is saturated with PTFE dispersion. Layers are applied to a mandrel and cold isostatically pressed. The pressed layer may be machined between applications and subsequent pressings. After all layers are applied and pressed, optionally including an outer ablation resistant random fiber reinforced PTFE composite, the densified structure is heat cycled above the crystalline melt point of the polymer to maximize mechanical properties.

Abstract: A radome being a unitary structure comprised of a fiber reinforced plastic is produced with a large percentage of the fibers being randomly oriented in a plane parallel to the inner surface of the radome. The radome is produced by packing a layer of fiber filled powder around a mandrel having its outer contour resemble the inner contour of the radome. The mandrel and packed powder are then subjected to isostatic pressing to properly orient the fibers. The radome is finished by sintering the powder and removing the finished form from the mandrel.

Abstract: A window construction and method are presented for electromagnetic signal transmission having broad bandwidth capability plus excellent resistance to ablation, rain erosion and thermal shock. The window is constructed of an odd number of three or more (i.e., 3, 5, 7, etc.) layers of reinforced PTFE material, with the dielectric constant of each layer (other than the core layer which is selected) being equal to the square root of the product of the dielectric constants of the two bordering layers. In a three layer version, the outer layers each have a dielectric constant which is the square root of the dielectric constant of the center layer; or, stated conversely, the center layer has a dielectric constant which is the square of the dielectric constant of each of the outer layers.

Abstract: A method of making a dielectric material comprising blending in a polymer dispersion, a particulate filler material having a high dielectric constant and microfibrous material to form a slurry of polymer, filler, and fiber. A flocculant is added to the slurry to agglomerate the polymer particles, the filler particles, and the microfibers to produce a dough-like material. The dough-like material is formed into a desired shape and then subjected to heat and pressure to densify the dielectric material.

Abstract: A radome and the method of manufacture thereof are presented wherein the radome is constructed from a series of rings of fiber reinforced polytetrafluoroethylene.

Abstract: A radome and the method of manufacture thereof are presented wherein the radome is constructed from a series of rings of fiber reinforced polytetraflouroethylene. The rings are machined from a cold molded PTFE-fiber composite billet and then loaded into a mold cavity. The rings are then subjected to heat and pressure to sinter them together. The resulting structure is machined into its final shape.

Abstract: Microwave circuit boards and methods of making microwave circuit boards, the circuit boards having relatively high dielectric constants, excellent moisture resistance, and reduced tendency to incur changes in dimensions after processing. The method comprises blending in a polymer dispersion, a particulate filler material having a high dielectric constant and microfibrous material to form a slurry of polymer, filler, and fiber. A flocculant is added to the slurry to agglomerate the polymer particles, the filler particles, and the microfibers to produce a dough-like material. The dough-like material is eventually formed into a sheet, and is thereafter dried. A conductive foil such as copper is then applied to both sides of the sheet to provide a microwave circuit board.

Abstract: A ceramic filled fluoropolymer-based electrical substrate material well suited for forming rigid printed wiring board substrate materials and integrated circuit chip carriers is presented which exhibits improved electrical performance over other printed wiring board materials and circuit chip carriers. Also, the low coefficients of thermal expansion and compliant nature of this electrical substrate material results in improved surface mount reliability and plated through-hole reliability. The electrical substrate material preferably comprises polytetrafluoroethylene filled with silica along with a small amount of microfiberglass. In an important feature of this invention, the ceramic filler (silica) is coated with a silane coating material which renders the surface of the ceramic hydrophobic and provides improved tensile strength, peel strength and dimensional stability.