Abstract: There is provided a sintered body at least 80% of which is constituted of a Y-type hexagonal ferrite. The sintered body contains, as main components, a cobalt oxide, a copper oxide, an iron oxide and AO (AO is at least one of BaO or SrO) in predetermined amounts in mol %, more preferably contains MO (MO is at least one of NiO, ZnO or MgO) in a predetermined amount in mol % in addition to the above components, and also contains, as additional components, bismuth oxide (Bi2O3), borosilicate glass, borosilicate zinc glass or bismuth glass in predetermined amounts in wt %. Thus, a sintered body which exhibits good magnetic properties and is usable up to a high frequency band ranging from several hundred megahertz to gigahertz, contains as few hetero phases other than a Y-type hexagonal ferrite as possible and can be calcined at a temperature of not higher than 1,000° C., particularly about 900° C., and a high-frequency circuit component using the sintered body can be provided.

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: There is provided a sintered body at least 80% of which is constituted of a Y-type hexagonal ferrite. The sintered body contains, as main components, a cobalt oxide, a copper oxide, an iron oxide and AO (AO is at least one of BaO or SrO) in predetermined amounts in mol %, more preferably contains MO (MO is at least one of NiO, ZnO or MgO) in a predetermined amount in mol % in addition to the above components, and also contains, as additional components, bismuth oxide (Bi2O3), borosilicate glass, borosilicate zinc glass or bismuth glass in predetermined amounts in wt %. Thus, a sintered body which exhibits good magnetic properties and is usable up to a high frequency band ranging from several hundred megahertz to gigahertz, contains as few hetero phases other than a Y-type hexagonal ferrite as possible and can be calcined at a temperature of not higher than 1,000° C., particularly about 900° C., and a high-frequency circuit component using the sintered body can be provided.

Abstract: The radio wave absorbent-assembling member comprises a radio wave absorptive thin material capable of assembling a structure in a desired form, wherein the thin material contains a conductive material therein and/or has on the surface thereof a conductive layer containing a conductive material, and a radio wave absorbent having a stereo-structure can be obtained by folding the above radio wave absorbent-assembling member and joining together the end portions of the thin material.

Abstract: The present invention can provide a MgCuZn-based ferrite sintered compact which is constituted by having as substantial main component compositions 7.5 to 23.0 mole % of magnesium oxide, 7.0 to 20.0 mole % of copper oxide, 19.0 to 24.2 mole % of zinc oxide and 48.5 to 50.3 mole % of ferric oxide, and the average particle diameter of the ferrite sintered compact is in a range of 1.10 to 7.30 &mgr;m while the standard deviation &sgr; of the size distribution is in a range of 0.60 to 10.00, resulting in the ferrite sintered compact which has a high impedance with a frequency of not less than 50 MHz and is capable of efficiently cutting of radiant noise by selecting inexpensive materials.

Abstract: There is disclosed a radio wave transmitting material, in which to opposite surfaces of a honeycomb structure obtained by laminating incombustible sheets prepared from a slurry containing a main component of an inorganic hydrate compound into a honeycomb shape using an inorganic adhesive, incombustible boards prepared from the slurry containing the main component of the inorganic hydrate compound are integrally bonded using an adhesive, whereby a radio wave transmitting material lightweight and superior in incombustibility and radio wave transmittance is realized.

Abstract: An electrically conductive member constituted by at least one member of the group consisting of carbon black, graphite and carbon fiber, a powdered or granulated material of an inorganic hollow body and inorganic reinforcing fiber are bonded to one another by an inorganic adhesive agent to thereby form an electric wave absorber. The electric wave absorber exhibits excellent electric wave absorbing power because of both the electrically conductive member and the powdered or granulated material of the inorganic hollow body which are contained in the electric wave absorber. The electric wave absorber has excellent mechanical strength because of the inorganic reinforcing fiber which is contained in the electric wave absorber. The electric wave absorber exhibits excellent nonflammable characteristic because of both the powdered or granulated material of the inorganic hollow body and the inorganic reinforcing fiber which are contained in the electric wave absorber.

Abstract: An incombustible honeycomb radio absorptive material is disclosed, forming a honeycomb structure that is an aggregate of many cells, wherein (i) the honeycomb structure contains a hydrated inorganic compound and an electrically conductive material, or (ii) the honeycomb structure contains a hydrated inorganic compound and has an electrically conductive layer made of an electrically conductive material being formed on the surface of the structure. A radio absorber is also disclosed, wherein a large number of the incombustible honeycomb radio absorptive materials are disposed on a shield panel or a ferrite tile covering he shield panel is provided. The incombustible honeycomb radio absorptive material and the radio absorber using it according to the invention are suitably used for an anechoic chamber and are excellent in the fire resistance and the radio absorption effect.

Abstract: Since the radio wave absorbent of the present invention has the main component of a magnesium-zinc system ferrite material containing 45 to 50 mol % of iron oxide, 7 to 19.7 mol % of magnesium oxide, 24 to 28.5 mol % of zinc oxide, 4 to 16 mol % of copper oxide, and 0.1 to 6 mol % of manganese oxide, a matching thickness is less than 8 mm, and the total weight of the radio wave absorbent for use in the inner wall of a radio wave dark room or the outer wall of a building or the like is remarkably reduced as compared with the radio wave absorbent obtained by sintering the conventional magnesium-zinc system ferrite material. Moreover, since the radio wave absorbent can be obtained by sintering the material at a relatively low sintering temperature of about 950 to 1150° C., the manufacture cost can be reduced relative to the radio wave absorbent obtained by sintering the conventional nickel-zinc system ferrite material.

Abstract: There is disclosed an MnMgCuZn ferrite material which contains ranges of 46.5 to 50.4 mol % of iron oxide, 10.5 to 22.0 mol % of magnesium oxide, 22.5 to 25.0 mol % of zinc oxide, 6.0 to 16.0 mol % of copper oxide, and 0.1 to 3.5 mol % of manganese oxide. Advantages of an MnMgCuZn ferrite material that resistivity is relatively high and material cost is low are utilized to realize a superior MnMgCuZn ferrite material which is much smaller in magnetic loss than conventional materials of the same series and which has a sufficient saturated magnetic flux density.

Abstract: A radio wave absorbent which comprises, as a main component, a manganese-nickel-copper-zinc system ferrite comprising 2.0 to 14.5 mol % of nickel oxide, 3.5 to 17.0 mol % of copper oxide, 30.0 to 33.0 mol % of zinc oxide, 0.5 to 10.0 mol % of manganese oxide, and 40.0 to 50.5 mol % of iron oxide. By virtue of the above-mentioned composition, the radio wave absorbent of the present invention is advantageous not only in that the reflectivity in a wide frequency band of from a low frequency is -20 dB or less, but also in that the matching thickness is small, thus enabling lowering of the production cost.

Abstract: The process for the preparation of an oxide magnetic compact of the invention comprises:a step of preparing a mixed material which comprises 44 to 50 mole % of iron calculated as Fe.sub.2 O.sub.3, 0.1 to 8 mole % of manganese calculated as Mn.sub.2 O.sub.3, with the sum of iron and manganese being 50 to 54 mole % calculated as Fe.sub.2 O.sub.3 and Mn.sub.2 O.sub.3, 20 to 38 mole % of magnesium calculated as MgO, 17 to 22 mole % of zinc calculated as ZnO and not more than 5 mole % of copper calculated as CuO, anda step of molding the aforesaid mixed material to a predetermined shape and then firing it in an atmosphere of low oxygen concentration of 2.5 to 12% by volume. Therefore, there appears an extremely excellent effect that the oxide magnetic compact having excellent electromagnetic properties can be obtained at low cost.