Abstract: An antenna element (115) of an antenna device has first and second root sections (117) and (118) and an intermediate section lying between the first and second root sections (117) and (118). A feed section (114) is provided in the first and second root sections (117) and (118). The first and second root sections (117) and (118) are arranged so as to surround the feed section (114), and are provided in a wind section (113). Tail end linear parts in the wind section (113) extend in respective opposite directions. At least one of the first and second root sections (117) and (118) has a wider width part, which is formed such that a portion that overlaps a feed line connected with the feed section (114) is larger in width than other portions. This makes it possible to realize high radiant gain and improve a VSWR characteristic for each radio wave.

Abstract: An antenna device (100) includes an antenna element (101) and an electric conductor plate (102) provided so as to face the antenna element (101). The antenna element (101) and the electric conductor plate (102) are short-circuited by a short-circuit section (104). The antenna element (101) is connected with both of external and internal electric conductors (122) and (123) constituting a feed line (121).

Abstract: A dipole antenna of the present invention is more compact and has a wider bandwidth as compared with a conventional dipole antenna. A dipole antenna (DP) includes antenna elements (E1) and (E2) on a single plane. (E1) includes a linear section (E1a) extending from an end of (E1) in a first direction, and a linear section (E1b) connected to (E1a) via a bending section (E1c), (E1b) extending from (E1c) in a direction opposite to the first direction. (E2) includes a linear section (E2a) extending from an end of (E2) in the direction opposite to the first direction, and a linear section (E2b) connected to (E2a) via a bending section (E2c), (E2b) extending from (E2c) in the first direction. (E1) and (E2) are such that (E1a) is provided between (E2a) and (E2b), and (E2a) is provided between (E1a) and (E1b).

Abstract: An object of the invention is to provide a small antenna which can cope with a wide band as well as has radiation characteristics stable in the wide band. The wide band antenna according to the invention is a wide band antenna in which a second radiation element and a first radiation element are disposed on the same substrate, and the substrate is bent on a straight line which is approximately parallel with a first straight line A approximately parallel with the disposition direction of the second radiation element and the first radiation element or rolled in a cylindrical shape which uses a straight line approximately parallel with the first straight line A as an axis direction. A power supply cable is disposed in parallel with the first straight line A.