Abstract: The present invention provides compositions of high frequency dielectric ceramics represented by the following formula:(1-y) SrTiO.sub.3 -y La(Zn.sub.1-x)/2 Mg.sub.x/2 Ti.sub.1/2)O.sub.3wherein 0.ltoreq.x.ltoreq.0.99; and 0.4.ltoreq.y.ltoreq.0.9. The compositions have a dielectric constant of about 28 to about 60, Qxf.sub.0 (GHz) of about 25,000 to about 71,000 and a temperature coefficient of the resonant frequency of about -56 to about 84 ppm/.degree. C. The compositions may be applied to various communications systems which require high frequency dielectric ceramics.

Abstract: This invention relates to a broad bandwidth electromagnetic wave absorber comprising a sintered ferrite and a CuO--Fe.sub.2 O.sub.3 system. The CuO--Fe.sub.2 O.sub.3 system, a spinel ferrite, has its own magnetic property, which makes it possible to be used for an electromagnetic wave absorber. The CuO--Fe.sub.2 O.sub.3 system is preferentially located at the grain boundary in the matrix ferrite. This resulted in increase in the total loss, decrease in matching thickness and shift in the center frequency.

Abstract: A composition of high frequency dielectric ceramics having a high unloaded Q value (Qu) and a high dielectric constant in a high frequency range such as micro- and millimeter wavelengths is disclosed. The composition according to the present invention is composed of the materials, (1-x)[Ba(Mg.sub.1/3 Ta.sub.2/3)O.sub.3 ]+xBaWO.sub.4 +0.1xMnO.sub.2 (0.01.ltoreq.x.ltoreq.0.09).

Abstract: Ferrites as an electromagnetic wave absorber have their unique attenuation ranges depending on their compositions. The possibility of controlling attenuation characteristics of ferrite absorber by forming laminates of ferrite is disclosed. This invention provides that the center frequency of laminated ferrites could be changed arbitrarily employing ferrite with different composition and thickness. The method consists of stacking at least two soft ferrite layers (Ni-Zn, Mn-Zn) with various thickness.

Abstract: Metal oxide group NTC theremistor material made from MnCO.sub.3 +NiO+CuO+Co.sub.3 O.sub.4 +FeO.sub.3 TiO.sub.2 group as a basic composition. The invention is characterized by metal oxide group thermistor material made from MnCO.sub.3 +NiO+ZnO+Co.sub.3 O.sub.4 +Fe.sub.2 O.sub.3 +TiO.sub.2 group or MnCO.sub.3 +NiO+CuO+ZnO+Fe.sub.2 O.sub.3 +TiO.sub.2 group as a basic composition having respectively composition amounts by weight for each ingredient described in the text. According to the invention, the sintering temperature of the material can be reduced relative to the conventional material, and therefore there is advantage that manufacturing expense of the thermistor can be reduced.

Abstract: An improved process for manufacturing a polycrystalline alumina fiber comprising dissolving aluminum alkoxide in alcohol, adding acetylacetone, hydrolyzing with water, and polymerizing to form a polymeric alumina sol and spinning the polymeric alumina sol by using a spinning apparatus.