Abstract: A circuit substrate includes a multi-layer substrate in which a plurality of dielectric layers are stacked, and a millimeter wave absorber provided inside the multi-layer substrate and having an electromagnetic wave absorption peak within a region of 30 to 300 GHz. An antenna element includes the circuit substrate described above, a power feeder provided inside the multi-layer substrate of the circuit substrate, and an antenna provided on a surface of the circuit substrate and connected to the power feeder. A method for reducing noise in a circuit substrate including a multi-layer substrate includes, by a millimeter wave absorber provided inside the multi-layer substrate and having an electromagnetic wave absorption peak within a region of 30 to 300 GHz, absorbing unnecessary electromagnetic waves diffused in the multi-layer substrate to reduce noise in the circuit substrate.

Abstract: A coating layer for a thermal insulator, in a laminated body for a thermal insulator, the laminated body including a carbonized-molded body and the coating layer for a thermal insulator which is layered on at least one surface of the carbonized-molded body, wherein the bulk density of the carbonized-molded body is 0.08 g/cm3 to 0.8 g/cm3 and the gas permeability ratio of the coating layer for a thermal insulator is 8.0 NL/hr·cm2 mmH2O or less.

Abstract: The present invention provides: an adhesive for a thermal insulator which does not allow the occurrence of the peeling-off and swelling of the layer in the repeating processes of increasing and decreasing temperature in a thermal insulator formed of a laminated matter having a carbon molded body in the layer structure thereof; and a laminated body using the adhesive. The adhesive is an adhesive for a thermal insulator including: (1) a raw material for carbonization with a carbonization ratio of 40% or more; (2) a heterocyclic compound which dissolves the raw material for carbonization; and (3) any of short carbon fibers and short fibers which are carbonizable and insoluble in the heterocyclic compound. The laminated body has a layer structure with a carbonized-molded body therein.

Abstract: Carbon fiber balls which enable quantitative, consistent supply into, for example, an extruder and also facilitate uniform dispersion of carbon fibers in the matrix of a resin by use of, for example, an extruder; as well as a process for the manufacture of the carbon fiber balls. The carbon fiber balls are constructed of short carbon fibers and a binder, and have a bulk density of 0.05-0.15 g/cm3. The process includes the steps of filling a mixer with short carbon fibers, the mixer having a hollow cylindrical container which is disposed substantially horizontally and a plurality of flat blades and a plurality of rake-shaped vanes disposed therein for rotating about the axis of the cylindrical container; rotating the flat and rake-shaped vanes simultaneously for a predetermined time; adding a binder to the contents of the mixer; and then rotating the flat blades for a predetermined time.

Abstract: A flexible carbon material is produced by carbonizing a composite material comprising carbon fibers having an average length of 6 to 50 mm and a binding agent. Carbon lumps are derived from the binding agent and are dispersed in a matrix of the carbon fibers so as to restrain a plurality of the carbon fibers while yet permitting relative slippage to occur as between the carbon fibers and carbon lumps such that the carbon fiber material exhibits a flexibility ratio D/d of not greater than 200 (where D is the diameter of curvature of the carbon material, when bent, just before breakage, and d is the thickness of the carbon material). The carbon fibers and lumps are preferrably present in an amount of from 5 to 50%, and 5 to 70% by volume, respectively, based upon the total volume of the carbon material.