Abstract: Grooves are formed on the connection faces of two dielectric base plates in a dielectric resonator. Internal conductors are provided on the inside faces. Coupling electrodes are formed on another dielectric base plate. These three dielectric base plates are connected so that the coupling electrode effects a capacity connection between the internal conductors. This arrangement permits an earth electrode (e.g., an external conductor) to be formed on almost the full exterior of the dielectric resonator, thereby preventing the reduction of the Qo of the resonator and electromagnetic field leakage.

Abstract: Dielectric resonator wherein an internal conductor non-formed portion is provided near one open face of the internal conductor formed holes, and signal input, output electrodes are provided on one portion of the external conductor, whereby electromagnetic field leakage is restrained, because the open face is not formed, and individual parts such as signal input, output pins and so on are not required.

Abstract: A dielectric resonator including a dielectric block through which an inner conductor formation hole passes; an inner conductor partially formed on an inner surface of the inner conductor formation hole; and an outer conductor formed on an outer surface of the dielectric block. A portion where the inner conductor is not formed is provided on the inner surface of the inner conductor formation hole in the vicinity of one open end portion of the inner conductor formation hole. A stepped portion is provided at a predetermined position on one of the inner surface of the inner conductor formation hole and the outer surface of the dielectric block. Two portions with corresponding resonant characteristics and respective line impedances different from each other are provided with a boundary defined by the stepped portion between the two portions.

Abstract: An air filter suitably usable in an air cleaner, room air-conditioner or especially in car air-conditioners in which air is driven at a high speed. The air filter is made of a pleated polyurethane foam having on one or both sides thereof a three-dimensional network skeletal structure of micro cells.

Abstract: A dielectric block having an external conductor on the outer surface and a plurality of holes with internal conductors formed therein; no internal conductors are provided near one end of each of the plurality of holes. Portions of the dielectric block and the external conductor are removed so as to obtain a dielectric resonator having desired resonator characteristics. In another embodiment, portions of the dielectric block are removed so as to bring the external conductor closer to the internal conductors thereby obtaining a dielectric resonator resonant with a desired frequency. The dielectric resonators limit leakage of electromagnetic field and do not require additional parts such as terminals and case.

Abstract: A compact dielectric resonator apparatus is comprised of a dielectric block having a plurality of mutually parallel throughholes formed therethrough with inner surfaces covered with a conductive film so as to provide coaxial resonators. The degree of coupling between a mutually adjacent pair of such dielectric resonators can be adjusted by forming grooves, a bottomed hole or a slit or burying a conductive plate therebetween in the dielectric block, and varying physical characteristics of such grooves, bottomed hole, slit and/or conductive plate, without changing the separations between the throughholes or the external dimensions of the dielectric block.

Abstract: Treatment of molten steel in a ladle, which comprises blowing inert gas into the ladle from its bottom, partially immersing a receptacle which covers the portion of the molten steel where the inert gas bubbles out and maintain non-oxidizing atmospheres within the receptacle with the gas so as to prevent oxidation of the molten steel by the slag.