Abstract: A plating method for an RF device is disclosed. The method includes (a) pre-treating the RF device made from a substrate material; (b) forming a copper plating layer by applying copper plating to the RF device; and (c) forming a thin-film layer over the copper plating layer, the thin-film layer made of a precious metal, where a thickness of the precious-metal thin-film layer is thinner than a skin depth at a working frequency band. The disclosed method makes it possible to provide a plating treatment with a low cost while providing a superior appearance quality.

Abstract: A tunable filter for expanding tuning range includes: a housing, which has multiple cavities defined by partitions; a resonator contained in the cavity; at least one sliding member installed over the resonator; a main cover coupled to an upper portion of the housing; and at least one tuning element coupled to a lower portion of the sliding member and made of a metallic material. Tuning is accomplished by a sliding motion of the sliding member, and the resonator includes a cylindrical first conductor and a second conductor coupled to an upper portion of the cylindrical conductor, where a cross section of the second conductor is shaped as a circle with a portion removed such that an area of overlap between the tuning element and the second conductor is varied according to a sliding of the tuning element.

Abstract: A frequency-tunable filter using a sliding system is disclosed. The frequency-tunable filter includes: a housing, in which a multiple number of cavities are defined by partitions; a sub-cover, which is coupled to an upper portion of the housing and in which a guide groove is formed; at least one sliding member installed in the guide groove; a main cover coupled to an upper portion of the sub-cover; a resonator held in the cavity; and at least one tuning element coupled to a lower portion of the sliding member to be inserted inside the housing, where tuning is achieved by a sliding movement of the sliding member, and at least one first guide member is coupled to at least one side surface of the sliding member such that the first guide member guides a sliding movement by way of contact with the side surface of the guide groove.

Abstract: Disclosed is an internal antenna that provides impedance matching for multiple bands. The antenna includes an impedance matching part, which in turn includes a first conductive element electrically coupled to a feeding point and a second conductive element electrically coupled to a ground, and at least one radiator electrically coupled to the first conductive element, where the first conductive element and the second conductive element of the impedance matching part are separated by a particular distance to perform coupling matching and are electrically coupled at a pre-designated position. Certain aspects of the present invention can be utilized to provide wide band characteristics in designing for multi-band applications, even for high-frequency bands.