Abstract: A ceramic filter comprising a plurality of three-terminal, dual-mode ceramic filter elements which are connected with each other through a capacitive coupling circuit which is adapted to increase the input/output impedance of the ceramic filter.

Abstract: A method and apparatus for manufacturing high-frequency coil devices, wherein a solid cylindrical rod-like mandrel having a coil element loaded thereon is inserted between lower and upper molds each of which is provided with a resilient layer, so that an annular cavity is defined between the peripheral surface of the mandrel and the resilient layers. The coil element is positioned within the annular cavity, and compressively enclosed by the resilient layers so as to be partially embedded therein, with the opposite end portions thereof being held in a fluid-tight manner between the resilient layers so as to be isolated from the mold cavity. A molten resin is injected into the mold cavity, and after the resin thus injected has been solidified, the resulting coil device is automatically removed from the mandrel through relative movement of the molds and mandrel.