RING ANTENNA

In order to obtain excellent electrical characteristics even when located in proximity to a conductor, a ring antenna (1) has a C-shaped loop element (22a) formed on the upper surface of a main body part (1a) comprising a ring-shaped dielectric material having a substantially square cross-sectional shape. A cut part (23a) is formed in a portion of this C-shaped loop element (22a), which is formed in the shape of a loop. In addition, an arc-shaped radiation element (21a) is formed on the inner circumferential surface of the main body part (1a) so as to be substantially concentric with the C-shaped loop element (22a), with a prescribed interval therebetween. The C-shaped loop element (22a) is excited by the radiation element (21a). The tip of a feed conductor (16) is connected to a feed part that is connected to one end of the radiation element (21a) formed on the lower surface of main body part (1a), and electrical power is fed to the radiation element (21a) from the feed conductor (16). Excellent electrical characteristics can be obtained with this ring antenna (1), even when housed in an exterior casing.